U.S. Environmental Protection Agency
Office of Water Supply
Washington, D.C.

This report has been reviewed by Black & Veatch.
EPA, and approved for publication. Approval does
not signify that the contents necessarily reflect
the views and policies of the' Environmental
Protection Agency, nor does mention of trade
names or commercial products constitute endorse-
ment or recommendation for use.

A.	PURPOSE 				.1-1
B.	SCOPE		.1-2
1.	Inorganic Chemicals	111-2
a.	Arsenic , 		111-2
b.	Barium 		 . -	III-4
c.	Cadmium	II1-5
d.	Chromium			 III-6
e.	Fluoride 		 ,	III-8
f.	Lead 			III-9
g.	Mercury			III-l 1
h.	Nitrate ............... III-13
i.	Selenium 		III-l 5
j. Silver			Ill-15
2.	Organic Chemicals ............ .111-17
a.	Chlorinated Hydrocarbon Insecticides	Ill-17
b.	Chlorophenoxy Herbicides 	Ill-19
3.	Turbidity 		 .111-20
4.	Coliform Organisms		III-21
5.	Radiological 			111-23
6.	Stabilization 		II1-2 5
1.	Chloride . 	II1-26.
2.	Color		111-27
3.	Copper 		111-28

Foaming Agents , . .
Hydrogen Sulfide . , .
PH 		 ..
Total Dissolved Solids (TDS)
a. Gravity Aeration ¦	
Mechanical Draft Aeration
Diffused Aeration 	
Applicability and Recommendations
a.	Air 		
b.	Chemical 		
c.	Applicability- and Recommendations-
Adsorption . . ... . .
a.	Activated Alumina	
b.	Activated Carbon 	
c.	Applicability and Recommendations
a.	Coagulation
b.	Rapid Mix
, c. Flocculation
d.	Sedimentation
e.	Softening
f.	Applicability arid Recommendations

5.	Filtration 			1V-23
a.	Gravity Filters ............ 1V-24
b.	Pressure Filters		 1V-24
c.	Diatomite Filters 	1V-25
d.	Media . 		; . . . . IV-25
1.	Single Media 			IV-25
2.	Dual Media 		IV-27
3.	Mixed Media 	' . . . . IV-28
e.	Backwashing Facilities . . . . . • . . . .' . IV-29
f.	Filtration Aids 		 IV-30
g.	Applicability and Recommendations 	IV-30
6.	Disinfection .x . 			 . . 1V-31
a.	Chlorine 			IV-32
b.	Hypochlorites 		 . IV-37
c.	Chlorine Dioxide 	- . IV-38
d.	Ozone		IV-38
e.	Applicability and Recommendations 	IV-39
7.	Stabilization 	IV-40
a.	Adjustments to pH	IV-40
b.	Polyphosphate 			IV-41
c.	Silicates 	1 • !	IV-41
8.	Ion Exchange 		! . . . . IV-41
a.	Softening by Ion Exchange 		IV-42
b.	Demineralization by Ion Exchange	1V-44
c.	Applicability and Recommendations 	IV-45
9.	Membrane Processes 1	IV-46
a.	Electrodialysis 	IV-46
b.	Reverse Osmosis . •	IV-49
c.	Applicability and Recommendations .... . IV-52
10. Fluoridation ,/Defluoridation	IV-53
a.	Fluoridation . 	IV-53
b.	Defluoridation 	' ' . '	IV-56
c.	Applicability and Recommendations 	IV-57

1,	Sampling and Analysis 		 , , . .IV-57
2,	Laboratory Facilities	IV-59
3,	Metering, Instrumentation, and Control	IV-60
1.	Sources, Quantities, and Characteristics of Wastes . . .IV-61
a.	Sources 		IV-61
b.	Quantities of Wastes Produced . 		IV-61
c.	Characteristics 	IV-64
2,	Waste Disposal Practices		 . IV-66
a.	Direct Disposal 			 . IV-66
b.	Vacuum Filtration	IV-66
c.	Centrifugation 	IV-66
d.	Drying Beds	IV-67
e.	Lagoons 		IV-67
f.	Discharge to Sanitary Sewers	IV-69
g.	Spent Brine Solutions	IV-70
h.	Summary of Waste Disposal Practices ..... IV-70
1.	Conventional Facilities . 			 . IV-71
a.	Turbidity Removal	.IV-71
b.	Ion Exchange 	IV-72
c.	Lime Softening			IV-72
d.	Iron and Manganese Removal 	IV-74
2.	Package Plants	IV-76
a.	Turbidity Removal	IV-78
b.	Taste and Odor Control 	IV-79
c.	Softening	IV-79
d.	Iron and Manganese Removal 	IV-79

1.	.Operator Training and Qualifications	V-6
2.	Improved Monitoring and Surveillance 	V-7
1.	Unit Processes	VI-4
a.	Mechanical Draft Aeration	' . . . . •. .	VI-S
b..	Diffused Aeration 		Vl-5
c.	Activated Carbon Beds 	VI-6
d.	Activated Alumina Columns	VI-6
e.	Rapid Mix		VI-7
f.	Flocculation . .		VI-7
' '	g.	Sedimentation 		VI-8
h.	Flocculator-Clarifier . ; 		VI-8
i.	Ion Exchange Softening		VI-9
j.	Pressure Filtration	VI-9
k.	Gravity Filtration 	VI-10
1.	Demoralization 	VI-10
m.	Electrodialysis 	•	VI-11
n,	Reverse Osmosis	VI-11
" *	o. Chemical Feed		VI-11
2.	Laboratory Facilities	VI-14
3.	Waste Disposal Facilities	VI-14
' 4.	Package Plants	'	VI-14
5. Upgrading Existing Facilities 	VI-15

1.	Unit Processes			. Vl-18
a.	Mechanical Draft Aeration	VI-19
b.	Diffused Aeration 	VI-19
c.	Activated Carbon Beds 		VI-19
d.	Activated Alumina Columns ........ VI-19
e.	Rapid Mix 	VI-20
f.	Flocculation	VI-20
g.	Sedimentation 	. . VI-20
h.	Flocculator-Clarifier 		VI-20
i.	Ion Exchange Softening 	VI-20
j. Pressure Filtration	VI-21
k. Gravity Filtration 		 VI-21
I. Demineralization 	VI-21
m. Electrodialysis 		 VI-21
n. Reverse Osmosis	VI-21
o. Chemical Feed 		 	VI-22
2.	Laboratory Facilities	VI-23
3.	Waste Disposal Facilities	VI-23
4.	Package Plants .	VI-23
5.	Upgrading Existing Facilities 	VI-23
1.	Example No. 1 . ;			.VI-24
a.	Capital Cost	VI-25
b.	Annual Operation and Maintenance Cost .... VI-27
2.	Example No. 2	¦	VI-28
a.	Capital Cost	VI-28
b.	Annual Operation and Maintenance Cost .... VI-29
3.	Example No. 3	VI-31
a.	Capital Cost	VI-31
b.	Annual Operation and Maintenance Cost .... VI-32

Following Page
Figure 1	Garnet t, Kansas Water Treatment Plant
Schematic			IV-71
Figure 2	Grant Park, Illinois Water Treatment
Plant Schematic 			IV-72
Figure 3	Troy, Kansas Water Treatment Plant Schematic .... IV-72
Figure 4	Cape Girardeau, Missouri Water Treatment
Plant Schematic 			IV-76
Figure 5	Mechanical Aeration Capital Cost	VI-33
Figure 6	Diffused Aeration Capital Cost 	VI-33
Figure 7	Activated Carbon Bed Capital Cost 	VI-33
Figure 8	Activated Alumina Column Capital Cost	VI-33
Figure 9	Rapid Mix Capital Cost , 	VI-33
Figure 10	Flocculation Capital Cost 	VI-33
Figure 11	Sedimentation Capital Cost .......... VI-33
Figure 12	Flocculator-Clarifier Capital Cost			.VI-33
Figure 13	Ion Exchange Softening Capital Cost 		 VI-33
Figure 14	Pressure Filtration Capital Cost 	VI-33
Figure 15	Gravity Filtration Capital Cost 	VI-33
Figure 16	Demineralization Capital Cost ¦	VI-33
Figure 17	Electrodialysis Capital Cost . . . • . -	VI-33
Figure 18	Electrodialysis Enclosure Capital Cost 	VI-33
Figure 19	Reverse Osmosis Capital Cost	VI-33
Figure 20	Reverse Osmosis Enclosure Capital Cost 	VI-33
Figure 21	Powdered Activated Carbon Chemical Feed
Capital Cost 			VI-33
Figure 22	Coagulant Chemical Feed Capital Cost	VI-33
Figure 23	Hydrated Lime Chemical Feed Capital Cost 	VI-33
Figure 24	Polymer Chemical Feed Capital Cost "	VI-33
Figure 25	Polyphosphate Chemical Feed Capital Cost 	VI-33
Figure 26	Chlorine Chemical Feed Capital Cost '	VI-33
Figure 27	Ozone On-Site Generation Capital Cost		 . VI-33
Figure 28	Calcium Hypochlorite Chemical Feed
Capital Cost 		VI-33

Following Page
Figure 29 Sodium Hypochlorite Chemical Feed	. .	¦ .
Capital Cost 			 VI-33
Figure 30 Sodium Hypochlorite On-Site; Generation
Capital Cost 			VI-33
Figure 31 Waste Solids Disposal Lagoon Capital Cost	VI-33
Figure 32 Package Plant Capital Cost	VI-33
Figure 33 Tube Settlers Capital Cost	VI-33
Figure 34 Labor—Plant Type 1 & 2
Operation and Maintenance Cost	. .VI-33
Figure 35 Labor—Plant Type 3 & 4
Operation and Maintenance Cost	VI-33
Figure 36 Mechanical Aeration Operation and Maintenance, Cost . ..VI-33
Figure 37 Diffused Aeration Operation and Maintenance Cost. • . . . VI-33
Figure 38 Activated Carbon Bed Operation and Maintenance Cost . VI-33
Figure 39 Activated Carbon Bed Media Replacement Cost .... VI-33
Figure 40 Activated Alumina Column Operation .and	.	...
Maintenance Cost			. VI-33
Figure 41 Activated Alumina Column Regenerative Chemical..Cost .. . VI-33
Figure 42 Rapid Mix Operation and-Maintenance. Cost	. . . . VI-33
Figure 43 Floeculation Operation and Maintenance Cost ...... . •• . VI-33
.Figure 44 Sedimentation Operation and Maintenance Cost .... . . VI-33
Figure 45 Flocculator-Clarifier.Operation and Maintenance Cost .• . ..VI-33
Figure 46 Ion Exchange Softening O.peration and Maintenance Cost . VI-33
Figure 47 Ion Exchange Softening Regenerative Chemical.Cost . . . .VI-33
Figure 48 Pressure Filtration Unit Process Operation
and Maintenance Cost 				. VI-33
Figure 49 Pressure Filtration Enclosure Operation
and Maintenance Cost . . . . . ...... . . . VI-33
.Figure 50 Gravity Filtration Unit Process Operation and
Maintenance Cost. . . ... ... . . ... . ¦ . .VI-33
Figure 51 Gravity Filtration Enclosure Operation and
Maintenance.Cost . . , . . . . . .. . . ; .. VI-33

Following Page
Figure 52 Demineralization Power and Enclosure Supplies
Operation and Maintenance Cost	VI-33
Figure 53 Demineralization Unit Process Supplies and
Regenerative Chemicals Operation and
Maintenance Cost	VI-33
Figure 54 Electrodialysis Unit Process Operation and
Maintenance Cost	. *	VI-33
Figure 55 Electrodialysis Enclosure Operation and
Maintenance Cost	VI-33
Figure 56 Reverse Osmosis Unit Process Operation
and Maintenance Cost 	VI-33
Figure 57 Reverse Osmosis Enclosure Operation and
Maintenance Cost . ;	VI-33
Figure 58 Powdered Activated Carbon Chemical Feed
Operation and Maintenance Cost	¦. . VI-33
Figure 59 Coagulant Chemical Feed Operation and
Maintenance Cost	VI-33
Figure 60 Hydrated Lime Chemical Feed Supplies
Operation and Maintenance Cost 		VI-33
Figure 61 Hydrated Lime Chemical Feed Power
Operation and Maintenance Cost	VI-33
Figure 62 Polymer Chemical Feed Unit Process
Operation and Maintenance Cost	VI-33
Figure 63' Polymer Chemical Feed Power and Enclosure
Operation and Maintenance Cost			VI-33
Figure 64 Polyphosphate Chemical Feed Operation and
Maintenance Cost	VI-33
Figure 65 Chlorine Chemical Feed Operation and
Maintenance Cost	VI-33
Figure 66 Ozone On-Site Generation Unit Process Operation
and Maintenance Cost	VI-33
Figure 67 Ozone On-Site Generation Enclosure Operation
and Maintenance Cost 	VI-33

Following Page
Figure 68 Calcium Hypochlorite Chemical Feed Unit
Process Operation and Maintenance Cost 	Vk-33
Figure 69 Calcium Hypochlorite Chemical Feed Power
and Enclosure Operation and Maintenance Cost , . .' . . VI-33
Figure 70 Sodium Hypochlorite Chemical Feed Unit
Enclosure Operation and Maintenance Cost ..... VI-33
Figure 71 Sodium Hypochlorite Chemical Feed Power
Operation and Maintenance Cost . ... . . . ... VI-33
. Figure 72 Sodium Hypochlorite On-Site Generation Unit
Process Operation and Maintenance Cost . , .'4 . . . VI-33
Figure 73 Sodium Hypochlorite On-Site Generation Power and
Enclosure Operation and Maintenance Cost . . ... VI-33
Figure 74 Lagoon Waste Solids Removal Cost		 VI-33
Figure 75 Package Plant Operation and Maintenance Cost .... VI-33

Table 1 Processes for Arsenic Removal 	*	111-3
Table'2 Processes for Barium Removal • , -	III-5
Table 3 Processes for Cadmium Removal .......... 111-6
Table 4 Processes for Chromium Removal 	III-7
Table 5 Processes for Fluoride Removal 		¦ . . . . III-9
Table 6 Processes for Lead Removal . . . ... .... . . IIT10
Table 7 Processes for Mercury Removal . . . . . . , . . 111-12
Table 8 Processes for Nitrate Removal 		111-14
Table 9 Processes for Selenium Removal . . . ... . . . . 111-16
Table 10 Processes for Silver Removal		III-16
Table 11 Processes for Endrin Removal ......... .111-18
Table 12 Processes for Lindane Removal . 		111-18
Table 13 Processes for 2, 4, 5^TP (Silvex) Removal . . . . . . 111-20
Table 14 Processes for Turbidity Removal ......... .111-21
Table 15 Processes for Bacteria Reduction		 . 111-23
Table 16 Maximum Contaminant Levels for Radioactivity	111-24
Table 17 Processes for Radionuclide Removal ....... .111-25
Table 18 Processes for Color Removal	: 111-27
Table 19 Processes for Copper Removal 	111-29
Table 20 Processes for Iron Removal 	111-31
Table 21 Processes for Manganese Removal 	II1-32
Table 22 Processes for Sulfate Removal 	II1-34
Table 23 Processes for Total Dissolved Solids Removal	111-35
Table 24 Processes for Zinc Removal 	111-36
Table 25 Solids Produced Based on Coagulant Dosage	IV-62
Table 26 Solids Produced From Taste and Odor Removal	IV-63
Table 27 Analysis of Spent Brine Solution 		IV-65
Table 28 Garnctt, Kansas Water Treatment Plant
Unit Process Design Data			IV-73
Table 29 AT&T — Grant Park, Illinois Water Treatment System
Unit Process Design Data 		IV-74
Table 30 Troy, Kansas Water Treatment Plant
Unit Process Design Data	IV-75

Table 31 Cape Girardeau, Mo. Water Treatment Plant
Unit Process Design Data	IV-77
Table 32 Comparison of Package Water Supply Treatment Systems . , IV-78
Table 33 Treatment Plant Design Capacity 	VI-1
Table 34 Water Treatment Chemical Costs	¥1-18
Table 35 Summary of Chemical Feed System
Operation and Maintenance Cost Curves 	Vl-22
Table 36 Capital Recovery Factors	VI-26
Table 37 Example Costs Summary 	VI-33

When the National Interim Primary Drinking Water Regulations were
promulgated late in 1975, it was estimated that there were about 40,000
community water systems (see Appendix A). Of this total more than 37,000
community systems each served 10,000 or fewer people. Thus, the vast
majority of community water systems would be considered small water systems
(capacities less than about 5700 rn^/day or 1.5 mgd). A previous study [1]
provided technical and economic information for the approximately 3000
community water treatment systems with capacities in excess of 3800 m^/day
(1 mgd).
An economic analysis [2J indicates water systems serving 25-99 persons
will need to spend a total of $6.2 — $9.1 million per year on monitoring,
capital investment, operation, and maintenance to meet the National Interim
Primary Drinking Water Regulations. An equivalent figure of S 109.4 — $151,3
million has been estimated for those systems serving from 100 to 9999 persons.
The economic impact on a specific system will depend on the degree of
treatment required to meet the regulations.
A pyRp0SE
This report is a planning tool which provides information on small water
treatment systems. The content of this report is directed to the governing
bodies responsible for the small water treatment systems so that they can
better understand what is required of them by the National Interim Primary
Drinking Water Regulations regarding treatment of their water and the related
costs. It is directed to the water plant operator or city engin'eer to assist one in
understanding what can be expected of various treatment processes with regard
to meeting the maximum contaminant levels (MCL) specified in the regulations.
"Maximum contaminant level" is defined as the maximum permissible level of a
contaminant in water when measured at the customer's tap. An exception is
turbidity where the maximum permissible level is measured at the water's point
Of entry to the distribution system. Finally the report is directed to consulting

engineers to assist them in planning for new and/or improved water treatment
systems. The report will provide the engineer with treatment techniques, design
parameters and cost information in regard to meeting the various MCL's.
The state of the art of water treatment for small water systems to
meet the drinking water regulations is presented in this report. The plant
capacities considered range from 230 -in^/'day (60,000 gpd) to S700
in ^/day (1.5 mgd), serving a population of 25 and 10,000 respectively.
Discussion of water supply sources compares ground and surface water sources
and covers means of protecting these sources from contamination. The MCL's
included in the regulations are presented along with applicable treatment
techniques and their efficiencies. Unit processes for the treatment of water are
discussed and general, design parameters have been compiled for each process.
These processes include disposal of the treatment plant wastes and laboratory
facilities required to monitor the treatment processes. Examples of conventional
water treatment processes for turbidity removal,, iron removal, chemical
softening (heavy metal removal), and ion exchange softening are explained. In
addition commercially available water treatment package plants are described.
Graphs of capital, operation, and maintenance costs show the costs for each
unit process and also for package plants. Examples of how to use the graphs
have also been provided to assist the user.

David Volkert and Associates, Monograph of the Effectiveness and Cost of
Water Treatment Processes for the Removal of Specific Contaminants,
68-01-1833, U.S. Environmental Protection Agency, August, 1974.
Energy Resources Company, Inc., Economic Evaluation of the Promul-
gated Interim Primary Drinking Water Regulations, U.S. Environmental
Protection Agency, U.S. Dept. of Commerce NTIS PB, 248 588,
October, 1975.

A variety of sources including surface water, ground water and
combinations of surface and ground water are used as water supply for small
water treatment systems. The selection of a supply source is dependent upon
availability, quality and quantity of water. Considering the small community
water systems, probably the majority use ground water as the source. The
reasons for this will be discussed subsequently.
Surface water sources include rivers, streams, lakes and reservoirs. Surface
water is generally available- across the United States except in the Southwest
where surface waters have high total dissolved solids (some are over 1000 mg/1)
[1J. These surface waters are generally unsuitable for potable water supply
without extensive treatment. Surface waters require at least turbidity removal
and disinfection before use as potable water. In some areas of the country,
particularly the Midwest and Western areas, the hardness of the surface waters
is high enough to require softening. The dissolved oxygen in most surface
waters prevents problems associated with iron, manganese, and hydrogen
sulfide. The bottom levels of some lakes and reservoirs may contain soluble
iron or manganese or hydrogen sulfide, but these contaminants can be avoided
by taking water with dissolved oxygen from a higher elevation in the body of
water using multilevel intakes. Other surface waters can exhibit special
problems with tastes, odors, color, inorganic contaminants, or pollution related
contaminants such as pesticides. River water presents additional treatment
complications due to seasonal variations in turbidity, mineral content, industrial
and sanitary waste discharges and other surface water related problems discussed
Very little protection can be given to some surface water sources. Gross
pollution of rivers and lakes can be prevented by the control of waste
discharges. Multipurpose reservoirs can receive some protection by proper
placement of adequate sanitary facilities. Single purpose water supply reservoirs
can be protected by prohibiting or controlling access to the reservoir watershed.

Ground water is generally available from wells throughout the United
States and from springs in some areas. The quality of ground water varies from
water needing only disinfection to water needing extensive treatment for
removal of total dissolved solids. Ground water can also require softening due
to the hardness content. Ground water can contain other substances such as
iron, manganese, hydrogen sulfide, carbon dioxide, radionuclides and inorganic
contaminants, particularly fluoride and nitrate. Treatment must be provided for
each of these if the substances exceed the established limits. Ground water
quality is generally constant and should not contain pesticide contaminants.
Since ground water is generally accessable and usually requires little treatment,
it is usually used as the water supply source for small systems.
Ground water sources can usually be protected by proper well
construction and maintenance. Prior to construction the well should be
properly located and during construction the well should be protected and
properly cased to prevent pollution.
When combinations of surface and ground water are used, the purpose is
usually to provide an adequate quantity of water. However, some combinations
are used to enhance the quality of the water. In very cold weather surface
water may be supplemented with ground water to raise the temperature of the
combined water and speed chemical reactions. In other instances a combination
of surface and ground water might be used in a split treatment softening
process. For most small systems a combination of surface and ground water
would not be economically justifiable.
Although most small water systems are in somewhat isolated locations,
some are located near larger systems or close to each other. For these small

systems a regional water system may be an attractive alternative to extensive
treatment for an individual system. Economies of scale dictate a large regional
system for those waters requiring significant degrees of treatment.
Another possible alternative for some small systems might be switching
water supply sources. A system using a surface water might be able to switch
to a ground water source requiring less treatment. Similarly, a system using
ground water might consider a surface water source or another ground water
aquifer in the area.

1. Dennis P. Tihansky, "Damage Assessment of Household Water Quality,"
Journal of the Environmental Engineering Division — ASCE, 905-918
(August, 1974).
American Water Works Association, Water Quality and Treatment, 3rd edition,
McGraw-Hill, New York, 1971.
Clark, Viessman and Hammer, Water Supply and Pollution Control, 2nd
edition, International Textbook, Scranton, 1971.
Tihansky, Dennis P., "Damage Assessment of Household Water Quality,"
Journal of the Environmental Engineering Division — ASCE, 905-918 (August,

The primary goal of a water treatment plant is to furnish water safe for
human consumption, A second basic objective is the production of water that
is appealing to the consumer. Quality guidelines are needed in order to evaluate
the suitability of water for public supply purposes. The United States
Environmental Protection Agency (USEPA) has developed primary and
secondary drinking water standards to replace the United States Public Health
Service Standards. Primary standards are based on dangers to health and they
are legally enforceable. If primary regulations are exceeded, either additional
treatment or an alternative water supply source is required to protect the
health of those persons using the water. Secondary regulations are based on
aesthetic considerations and are not enforceable by the USEPA, but may be
enforced by the States, Violation of these aesthetic standards should be
avoided, if possible, to discourage the consumer from turning to some other,
unsafe water.
The USEPA has published National Interim Primary Drinking Water
Regulations (Federal Register, Vol. 40, No. 248, December 24, 1975 & Vol. 41,
No. 133, July 9", 1976, see Appendix A) which became effective in June 1977.
These primary standards" xonstitute legal requirements for public supplies,
because they deal 'with substances which are hazardous to health. The fact that
standards are to be periodically reviewed and can be amended and revised by
the USEPA must be considered in determining the need for treatment of a
particular water supply.
The primary regulations include standards for inorganic and , organic
chemicals, turbidity, col if or m bacteria and radionuclides. It is of importance
that the applicable standards are met at the customer's tap except the turbidity
standard which must be met at the point of entry into the distribution system.
Therefore, production of water that does not incur contamination from the
distribution system is necessary.

The process removal percentages presented for the various contaminants in
the following sections are for a single pass through the process. If a single pass
will not reduce the contaminant to the required MCL, then multiple stages of
the same process or two or. more processes in series might be used.
1. Inorganic Chemicals
A discussion of the significance, possible sources, and processes applicable
to small public water systems for the removal of each inorganic substance for
which limits have been established is included in the following paragraphs.
a. Arsenic. Arsenic is highly toxic and the ingestion of as little as
100 mg can result in severe] The maximum contaminant level for
arsenic is 0.05 mg/1. The occurrence of arsenic in the environment is due
mainly to natural deposits of the metalloid and to its extensive use in
pesticides. Other sources of contamination include manufacturing processes
such as tanning, dye manufacture and lead shot manufacture and to its use as a
wood preservative. The arsenic concentration of most treated drinking water
supplies in the United States ranges from less than 0.03 to 0.10 mg/1.[2]
High concentrations of arsenic compounds have , been found to occur
naturally in some waters of the Western United States.
Selection of a treatment method for arsenic removal is dependent on
' valence form and initial concentration of the arsenic. The two common valence
forms are arsenite and arsenate. Also called arsenic III (this indicates a valence
of +3), arsenite is a naturally occurring substance and is usually found only in
ground water. Arsenic V (this indicates a valence of +5), or arsenate, can be
found in ground water as a naturally occurring substance and in surface water
as both a natural and industrial pollutant. In water, both valence forms exist in
a relatively insoluble state, except as the sodium or potassium salts.
Various treatment processes will remove arsenic from drinking water.
Table 1 [3. 4] lists unit processes and per cent removals of arsenic for each unit
III-2 •

Table 1
Unit Process*
Per Cent Removal
Coagulation, Sedimentation,
and Filtration
Lime Softening
Ion Exchange**
Reverse Osmosis***
Adsorption (Alumina)
*Additional process information is discussed in the text follow-
ing this table.
**Anion exchange resin.
•"'Predicted but not experienced.[3]
Laboratory experiments and pilot plant studies have shown that for
coagulation and lime softening, arsenic removals are dependent on the pH of
the water, coagulant dose and initial arsenic concentration-. The following
results [5] were observed during these studies and experiments:
1.	Arsenic III removal
Chemical coagulation or lime softening can achieve adequate removals
of arseniclll, if the arsenic concentration is only slightly above the MCL.
Otherwise, oxidation of arsenic III to the arsenic V form is necessary
before treatment. Use of oxidants such as ozone and potassium
permanganate will be effective on arsenic III. The use of chlorine as
an oxidant for arsenic III removal is not advisable as chlorine can
react with certain organic jmaterials to produce chloroform and other
2.	Arsenic V removal
a. For initial arsenic concentrations less than 1.0 mg/1, coagulant
dose (alum or ferric sulfate) of 20 to 30 mg/1 and pH between

5.0 and 7.5, arsenic removals of greater than 90 per cent were
b.	For initial arsenic concentrations peater than 1.0 mg/1 and other
conditions as above, arsenic removals decreased as initial
concentration. increased. Larger doses of coagulant, however,
achieved higher removals.
c.	For initial arsenic concentrations up to 10 mg/1 and pH of 10.8
and above, lime softening can achieve 95 per cent removals.
Below a pH of 10.3. removals decreased to about 30 per cent as
the pH decreased to 8.5.
Ferric chloride and ferrous sulfate have also been used successfully as
coagulants for arsenic removal. [3]
b. Barium. Drinking water should not contain barium in concentrations
exceeding L0 mg/1 because of the toxic effects it has on the heart, blood
vessels and nerves.[l] Barium may be found in some ground waters and in
runoff from areas where barite and witherite are mined. Industrial applications
of barium and its salts include metallurgy, paint manufacture, ceramic and glass
manufacture and other processes. Wastes from these plants may contain
significant levels of barium contamination. Barium concentrations ranging from
0.0 to 1.55 mg/1 have been found in United States treated water supplies.[2]
In addition, several cities and subdivisions have been identified by the State
of Illinois EPA as using well water sources with barium concentrations
greater than the MCL; the highest concentration found was 10 mg/1.[6]
A number of treatment methods can effectively remove barium from
drinking water as shown in Table 2. [3, 5]
Studies have shown that lime softening is capable of achieving 90 per cent
barium removal if the pH is between 10 and 11 and if the initial barium level is
approximately 17 mg/1 or less.[5] Below and above this pH range, removals
decreased. Conventional coagulation is not recommended for barium removal
unless the barium concentration is only slightly above the allowable maximum
of 1.0 mg/1. Removals of only 20 to 30 per cent were achieved even when
coagulant doses of 120 mg/1 were used.

Table 2
Unit Process*
Per Cent Removal
Excess Lime Softening
Reverse Osmosis**
Ion Exchange
Electrodialysis* *
* Additional process information is discussed in the text
following this table,
"Predicted but not experienced.[3]
Conventional ion exchange softening treatment can very effectively remove
barium from water. As a result _ of the similarity in behavior of hardness and
barium in ion exchange treatment, the. hardness test can be used to monitor
barium during treatment. When blending is used, caution should be exercised to
prevent excessive barium levels in the finished water.
c. Cadmium. Current evidence indicates that cadmium is biologically a
nonessential, nonbeneficial element of high toxic potential. [1 ] Poisoning from
cadmium-contaminated food and beverages has been documented; ingestion of
cadmium has been associated with hypertension. Cadmium may leach from
galvanized pipes or fixtures used in a water supply system. Only minute traces
of cadmium are found in ground water. However, high concentrations may be
found in surface waters as a result of wastes from the following industries:
electroplating, pesticides, photography, metallurgy and ceramics.
In, water supply systems, cadmium has been found in concentrations
ranging from less than 0.02 me/1 to 3.94 mg/1.[2] The maximum allowable
level of cadmium in drinking water supplies is 0.010 mg/1. Selection of a
treatment method depends on whether the cadmium to be removed is soluble
or insoluble. Table 3 [3,5]lists unit processes for removal of both insoluble
•and soluble forms. The chloride, nitrate and sulfate compounds of cadmium
are highly soluble in water, but the carbonate and hydroxide compounds are

Table 3
Unit Process*
Per Gent Removal
Removal of soluble forms of cadmium:
Reverse Osmosis**
Ion Exchange**
Removal of insoluble forms of cadmium:
Coagulation, Sedimentation and Filtration
Lime Softening
~Additional process information is discussed in the text following this table.
**Prcdicted but not experienced.[3J
***Applies only to prevention of corrosion of galvanized piping materials in the
distribution system.
Studies have shown that lime softening is effective if the pH is 8.5-11.3.
Cadmium removals by coagulation are also dependent on pH with the removal
efficiency increasing with increased pH.[5] Based on laboratory studies,
coagulation using ferric sulfate has been more effective than using alum. If the
pH is increased to greater than 1,5, soluble forms of cadmium will form
insoluble compounds and can be removed by coagulation or lime softening as
outlined above.
d. Chromium. Chromium exists in two common valence forms. III and
VI. Chromium is toxic to humans, particularly in the hexavalent state (VI). It
can produce lung tumors when inhaled and is a potent sensitizer of the skin. [ 1 ]
The maximum contaminant level for chromium has been set at 0,05 rng/1-
Sources of chromium contamination in drinking water are largely the
result of industrial pollution. Chromium salts are used in the metal finishing

industry, in the tanning industry and the manufacture of paints, dyes,
explosives, ceramics, paper and many other substances. Chromium compounds
may also be present in the discharge of cooling waters where the water has
been treated with chromium to inhibit corrosion. The chromium concentration
of most treated drinking water supplies ranges from O.Q to 0.079 mg/1. [2]
If treatment for chromium removal is required, the form of chromium,
whether soluble or insoluble, should be identified prior to selection of the
treatment system. Chloride, nitrate and sulfate salts of trivalent chromium are
readily soluble; however, the hydroxide and carbonate compounds are
insoluble. Of the hexavalent salts only sodium, potassium and ammonium
chromates are soluble. The corresponding dichromates are also quite soluble.
Table 4 [3, 5] lists unit processes for the removal of both insoluble and soluble
Table 4
Unit Process*
Per Cent Removal
Removal of soluble forms of chromium;
Reverse Osmosis**
Ion Exchange**
Removal of insoluble forms of chromium III:
Coagulation, Sedimentation,
and Filtration
Lime Softening
Removal of insoluble forms of chromium VI:
Coagulation, Sedimentation,
and Filtration
Lime Softening
~Additional process information is discussed in the text following this table.
••Predicted but not experienced.[3]

Removal of insoluble chromium III can be achieved by alum or iron
coagulation or by lime softening. Studies have shown that pH has only a slight
effect on removals by alum and iron coagulation. Lime softening removals,
however, decrease as the pH drops below 10.6.
Insoluble chromium VI is more difficult to remove by conventional
treatment than insoluble chromium III. Laboratory studies showed that alum
coagulation and lime softening obtained only 10 per cent removal and ferric
sulfate coagulation at best removed 35 per cent of chromium VI. Ferrous
sulfate coagulation, however, achieved removals of 98 per cent.[5]
Chlorination prior to treatment for chromium removal is not recom-
mended because of the possible oxidation of chromium III to chromium VI. If
chlorination before treatment for chromium removal is necessary, ferrous
sulfate is recommended as a coagulant. Prechlorination is also not advisable as
chlorine can react with certain -organic materials to produce trihalomethanes.
e. Fluoride. While fluoride is added to some water supplies to aid in
prevention of dental caries, some communities have the problem of excessive
amount of natural fluoride in their raw water. Excessive fluoride in drinking
water supplies produces dental fluorosis.[1 ] This mottling of the teeth increases
with increasing fluoride concentration.
Only a few regions in the United -States ¦ contain large deposits of
fluoride bearing rock. Fluorides in high concentrations are not common in
surface waters, but may occur in detrimental concentrations in ground water.
Fluorides are used as insecticides, disinfectants, in steel manufacture, for
preserving..wood, and in the manufacture of glass and enamels. Although they
are not normally found in industrial wastes, fluorides may be present as a
result of accidental spillage. Fluoride will be introduced to surface water by
communities which practice fluoridation and then discharge sanitary wastes to
a surface water.
The - amount of water, consequently the amount of fluoride, ingested by
people in a given community is primarily a function of air temperature.
Depending on the annual. average air temperature, the maximum allowable
level of fluoride ranges from 1.4 to 2.4 mg/1, (Refer to Appendix A for
specific allowable levels of fluoride.) Fluoride has been found in water supply
systems in concentrations ranging from less than 0.2 mg/1 to 8.0 mg/1. [2,7]

Communities with excessively high natural fluoride levels can utilize any of a
variety of defluoridation processes. Processes for fluoride removal are listed in
Table 5.[31
Table 5
Unit Process*
Per Cent Removal
Reverse Osmosis**
Ion Exchange/Adsorption**
Excess Lime Softening
•Additional process information is discussed in the text
following this table.
**Predicted but not experienced. [3]
The method most commonly used for fluoride removal is the ion
exchange/adsorption process using either bone char or activated alumina as the
exchange resin. Bone char readily removes both fluoride and arsenic; however,
arsenic can interfere with fluoride removal when using bone char. Investigations
showed that bone char which had adsorbed arsenic could not be regenerated. [4]
Activated alumina, however, is readily regenerated when both fluoride and
arsenic are removed. Therefore, activated alumina is the recommended medium to
use for fluoride removal if the raw water contains both fluoride and arsenic.
Where excess lime softening is used for treatment.of high magnesium
water, it has been demonstrated that fluoride is removed by coprecipitation with
magnesium hydroxide.[8] Fluoride removal is directly related to the amount of
magnesium removed. This is indicated by the range of per cent removals in
Table 5. If excess lime softening is to be used for fluoride removal, raw water
quality may require the addition of magnesium to achieve adequate reduction
of fluoride.
f. Lead. Drinking water should not contain lead in concentrations
exceeding 0.05 mg/1. Excess lead is a serious health hazard especially in

children. Lead poisoning in children can cause brain damage and kidney damage
sometimes resulting in death. [ 1 ] The most likely sources of lead pollution are
industrial and mining effluents. Natural waters have been known to contain as
much as 0.4 to 0.8 mg/1 of lead, but this situation is rare. Another source of
lead contamination is lead pipe used for water supply systems. If contamination
is due to lead pipes, the best method of control is pipe replacement. Where
replacement of the piping system is not practicable. pH control and
stabilization is the alternative. Concentration of lead in finished drinking water
supplies ranges from 0.0 to 0.64 mg/1.[2]
Lead concentrations in water can be removed by the treatment methods
listed in Table 6.[3, 5] Selection ofa treatment method is dependent on the
form of lead, whether soluble or insoluble. The carbonate and hydroxide
compounds of lead are insoluble; the sulfate and various other lead salts are
Table 6
Unit Process*
Per Cent Removal
For removal of.soluble forms of lead:
Reverse Osmosis**
Ion Exchange**
For removal of insoluble forms of lead:
Coagulation, Sedimentation,
and Filtration
Lime Softening
•Additional process information is discussed in the text following this table.
* "Predicted but not experienced; [3]
""•Applies only to prevention of corrosion of lead piping materials in the
distribution system.

Insoluble forms of lead are the most common, therefore conventional
treatment methods of coagulation, sedimentation and filtration, or lime
softening will usually be adequate for lead removal. Laboratory studies showed
that ferric sulfate is a more effective coagulant than alum in removing lead. [ S ]
g. Mercury. Exposure to mercury and its compounds poses a serious
threat to man's health. Continued ingestion of small concentrations of mercury
or a one time ingestion of a larger amount can damage the brain and central
nervous system. [ 11 The maximum allowable level of mercury in drinking water
is 0.002 mg/1. Most water supplies in the United States do not contain mercury
or any of its compounds. Studies indicate that mercury in the United States
treated water supplies varies in concentration from 0.0 to 0.033 mg/1.[2]
Industrial and agricultural applications are the most likely source of
mercury contamination. Mercury compounds are used in explosives, antiseptics,
printing, electroplating, herbicides and fungicides. Mercury may occur in either
the inorganic or organic form. The organic form is more important as it is the
more toxic form, the form most likely to be found in water, and the more
difficult form to remove by conventional treatment.!5] In order to. select the
proper treatment method, the form of the mercury contaminant, organic or
inorganic, should be determined. Listed in Table 7 [3.5] are treatment methods
for mercury removal.
Inorganic mercury removals using coagulation, sedimentation and filtra-
tion, or lime softening are dependent on pH of the water. [ 51 It has been
reported that ferric sulfate coagulation achieved 66 per cent removal at pH 7
and 97 per cent removal at pH 8 for a dosage of 18 mg/1 on water containing
0.05 mg/'l of incrrganic mercury. Alum coagulation is less effective; removals of
74 per cent at pH7 and 38 per cent at pH 8 have been shown. Also, as the
turbidity increases, removals by coagulation increase.
Lime softening is moderately effective for inorganic mercury removal,
depending on the pH of the water. Studies have shown that in the 10.7 to
11.4 pH range removals were 60 to 80 per cent, but only 30 per cent was
removed at pH 9.4.
III-l 1

Table 7
Unit Processes*	Per Cent Removal
For removal of inorganic forms of mercury:
Coagulation, Sedimentation.
and Filtration	38—97
Lime Softening	30—80
Granular Activated Carbon	less than 80
>..• Ion-Exchange	95-98
Reverse Osmosis**	90-97
Electrodialysis**	80
r I
For removal of organic forms of mercury:
Coagulation, Sedimentation,
and Filtration	30-85
Granular Activated Carbon	greater than 80
Ion Exchange	95—98
Reverse Osmosis**	90—97
Electrodialysis**	80
~Additional process information is discussed in the text following this table.
~~Predicted but not experienced.[3]
Activated carbon has been studied for inorganic mercury removal.
Powdered activated carbon will increase removals above that obtained with
coagulation alone. However, doses required to produce significant increases are
much higher than normally used for taste and odor control. Granular activated
carbon was found to be fairly effective although removals are dependent on
contact time and amount of water treated. Inorganic mercury removals of
approximately 80 per cent have been achieved for 15,000 bed volumes of water
(a bed volume is equal to the volume of activated carbon used) with
3.5 minutes contact time on water containing 0.020 to 0.029 mg/1 of mercury.

Several preliminary experiments indicate that the ion exchange process
should be an effective method for inorganic mercury removal. These studies
showed that as much as 90 per cent of inorganic mercury can be removed by
cation and anion exchange resins in series.
Organic mercury is more difficult to remove from drinking water, by
conventional treatment methods, than inorganic mercury. Laboratory experi-
ments and pilot plant studies have shown alum and iron coagulation to achieve
lower organic mercury removals than inorganic mercury under the same test
conditions. Lime softening was also studied and found to be ineffective for
organic mercury removal.
Both powdered and granular activated carbon are effective for organic
mercury removal. Approximately 1 mg/1 of powdered activated carbon is
required for each 0.0001 mg/1 of mercury to be removed from water to reach a
residual level of 0,002 mg/1. Removal of organic mercury using granular
activated carbon was found to be dependent on contact time and amount of
water treated, similar to that found for inorganic mercury. Organic mercury
removals of approximately 80 per cent have been achieved for 25,000 bed
volumes of water with 3.5 minutes contact time on water containing 0.020 to
0.029 mg/1 of mercury.
Preliminary studies carried out on ion exchange for organic mercury
removal indicate results similar to those for inorganic mercury. Removals of
98 per cent were achieved using cation and anion exchange resins.
h. Nitrate. Nitrate in drinking water can cause a temporary blood
disorder in infants called methemoglobinemia (blue baby). Serious and
occasionally fatal poisonings in infants have occurred following ingestion of
waters containing nitrate concentrations greater than 10 mg/1 (as nitrogen).[ 1 ]
Thus the maximum allowable level of nitrate in drinking water is 10 mg/1 (as
nitrogen). This is equivalent to 45 mg/1 of the nitrate ion (NOj). Studies
indicate that nitrate in treated water supply systems varies from 0.02 to
28.2 mg/1 (as nitrogen). [2]

Ground waters may acquire nitrates by percolation in areas using nitrate
fertilizers and by cesspool leachings. In addition, nitrates may be added to a
surface or ground water that receives wastes from chemical fertilizer-producing
plants and municipal wastewater treatment plants. Nitrate contamination of
ground water supplies can often be prevented by proper well construction.
Treatment methods for the removal of nitrate from water are listed in
Table 8.C3]
Table 8
Unit Processes*	Per Cent Removal
Reverse Osmosis * *	90 - 97
Electrodialysis*?	80
Ion Exchange	98
~Additional process information is discussed in the text
following this table.
**Per cent removal based on manufacturers' recommendations.
Nitrate salts are very soluble; therefore, nitrate removal cannot be achieved
by processes such as lime softening or coagulation. Presently the most practical
method of removing nitrate from drinking water is by ion exchange
treatment.[5]	¦
Anion exchange resins can be used to remove nitrate by replacement with
chloride. However,, pretreatment of water to reduce sulfate, iron or silica
concentrations may be required for efficient operation of the exchanger.
Sulfate decreases the resins' capacity for nitrate removal, thus more frequent
regeneration of the system is required. Iron and silica interfere by clogging the
resin, thus preventing the nitrate from being exchanged.
Use of a cation exchange resin and anion exchange resin (demineralization)
might be necessary if the chloride level in the finished water becomes
undesirably high.

i. Selenium. Selenium in large amounts is toxic to both humans and
animals. [ 1 ] There is also concern over the possible carcinogenic properties of
the element. More recent findings suggest that small amounts may be beneficial.
The current limit of selenium in drinking water is 0.01 mg/1. Concentrations of
selenium ranging from 0.003' to 0.07 mg/1 have been found in water supply
systems in'the United States.[2]
Some soils, particularly in South Dakota and Wyoming, contain excessive
amounts of selenium. Irrigation return flows from these soils may contain
undesirably high levels of contamination. Selenium pollution may also result
from industrial manufacture of paint, dye, insecticide and rubber.
Prior to selection of a treatment process for removal of selenium, the form
of the contaminant should be identified. The two forms, selenium IV (selenite)
and selenium VI (selenate*), require significantly different treatment methods for
i	- :
effective removal. Refer to Table 9 [3, 5] for appropriate processes for removal
of selenium.
Alum and ferric sulfate coagulation, and lime softening* are only
moderately effective on the removal of selenium IV from water. [5] Of these
three methods, tests indicate that ferric sulfate coagulation is the most effective
for removal of selenium IV. The best removal was achieved at the low pH of
5.5 and a trend of decreasing removal with increasing pH was observed.
Tests have shown that alum, ferric sulfate and ferrous sulfate coagulation,
and lime softening are ineffective methods for selenium VI removal from
drinking water. As indicated in Table 9, reverse osmosis and ion exchange are
effective methods for removing both forms of selenium.
j. Silver. A study of the toxic effects of silver added to drinking water
of rats showed pathologic charges in kidneys, liver, and spleen. [1] The
maximum allowable level of silver in drinking water is 0.05 mg/1. Concentra-
tions of silver ranging from 0.0 to 0.03 mg/1 have been found in treated water
supply systems in the United States. 12] Table 10 [3,5] lists unit processes and
their effectiveness for removing silver from water supplies.

Table 9
Unit Process*	Per Cent Removal
For selenium IV:
Coagulation, Sedimentation,
., and Filtration	10—85
Softening	20—45
For selenium VI:
Coagulation, Sedimentation,
and Filtration	0-10
Softening	0—10
For either or both selenium forms:
Reverse Osmosis'	90-97
Electrodialysis**	80
Ion Exchange -	95
•Additional process information is discussed in the text preceding this table.
•Predicted but not experienced, [3]
Table 10
Unit Process*	Per Cent Removal
Coagulation, Sedimentation,
and Filtration	70-90
Lime Softening	70—90
Reverse Osmosis**	90—97
Electrodialysis**	80
Ion Exchange**	95
~Additional process information is discussed in the text
following this table.
~ ~Predicted but not experienced. [3]

Both alum and ferric sulfate coagulation are effective in removing silver
from drinking water.[5] Alum coagulation removals are pH dependent; above a
pH of 8, removals decreased with increasing pH. Both ferric sulfate and lime
softening removals increase as the pH is increased.
2. Organic Chemicals
The organic chemicals included in the National Interim Primary Drinking
Water Regulations can be divided into two classifications; (a) chlorinated
hydrocarbon insecticides and (b) chlorophenoxy herbicides. The insecticides
consist of endrin, lindane, methoxychlor and toxaphene; the two herbicides
included are 2, 4—D and 2, 4, 5—TP (Silvex).
a. Chlorinated Hydrocarbon Insecticides. Manufactured by numerous
companies, these synthetic organic insecticides are widely used, are long-lasting
in the environment and are very toxic to humans. The symptoms of poisoning,
regardless of the compound involved, are similar. When chlorinated hydro-
carbons are absorbed into the body, small amounts are stored in the body fat.
Long-range effects of the accumulation of these insecticides in the body are
generally unknown. If any of these complex organic compounds are ingested in
large amounts, death can result from cardiac or respiratory arrest. [ 1 ]
Maximum contaminant levels established for the chlorinated hydrocarbons
(refer to Appendix A) are listed as follows:
The 1969 National Community Water Supply Study indicated pesticide
concentrations in drinking water are generally lower than the allowable
limits.[9] Summarized in Table 11 [5] are unit processes and their effectiveness
for removing endrin from water supplies.
(a)	F.ndrin
(b)	Lindane
(c)	Methoxychlor
(d)	Toxaphene
0.0002 mg/1
0.004 mg/1
0.1 mg/1
0.005 mg/1

Table 11
Unit Process
Per Cent Removal
Chlorination, 5 mg/1
Coagulation, Sedimentation,
less than 10
and Filtration
Powdered Activated Carbon*;
10 mg/1
20 mg/1
Granular Activated Carbon*,
30 nr/rn^/day (0,5 gpm/ft2)	99
~Preceded by coagulation, sedimentation and filtration.
Unit, processes applicable for lindane removal are listed in Table 12.[5]
Conventional treatment processes are ineffective for reducing lindane levels and
therefore are not included in Table 12. Oxidation is also not included in
Table 12 as experiments have shown only ozone, in uncommonly high
concentrations, to have any appreciable effect in reducing the lindane
Table 12
Unit Process
Per Cent Removal
Powdered Activated Carbon*:
5 mg/1
10 mg/1
20 mg/1
Granular Activated Carbon*,
30 m3/m2/day (0.5 gpm/ft2)	99
•Preceded by coagulation, sedimentation and filtration.

Reverse osmosis has also been studied for lindane removal but it is currently
impractical for that purpose. 15]	¦ ¦
Treatment information is currently not available regarding removal of
methoxyehlor from drinking water. One publication [5], however, predicts that
adsorption with granular activated carbon would effectively remove this
contaminant from a water supply.
In regard to removal of toxaphene from drinking water, coagulation,
sedimentation, filtration and chlorination have proved ineffective. The
recommended treatment method for toxaphene removal is adsorption with
activated carbon. Tests have shown a powdered activated carbon dosage of
5 mg/1 to reduce toxaphene concentrations by 93 per cent.[5]
b. Chlorophenoxy Herbicides. Chemical control of aquatic vegetation is
the principal source of the chlorophenoxy herbicides in drinking water. The
two herbicides included in the drinking water regulations are 2, 4—D and 2, 4,
5—TP (Silvex). Manufactured and sold under various trade names, these
compounds have toxic properties of a generally lower order than chlorinated
hydrocarbons. [ 1 ] Nevertheless, herbicides should be used carefully so as not to
contaminate drinking water.
The maximum allowable levels of 2, 4-D and 2, 4, 5-TP (Silvex) are,
0.1 mg/1 and 0.01 mg/l, respectively. The only effective treatment process at this
time for removal of 2, 4—D is adsorption using activated carbon. Conventional
water treatment processes (coagulation, sedimentation, filtration and oxidation)
have been shown to be ineffective for 2, 4—D removal.[5] Reverse osmosis is a
potential process for removing 2, 4—D from drinking water. However, sufficient
data are not available at this time to recommend it as a practical technique.
Treatment data for the removal of *2, 4, 5—TP (Silvex) are presently not
available. It has been assumed that this herbicide would behave in a manner
similar to 2, 4. 5—T and Table 13 is a summary of expected removals.[5]

Table 13
Unit Process
Per Cent Removal
Chlorination. 5 mg/1
Coagulation and Filtration
Powdered Activated Carbon:
less than 10
5 mg/1
10 mg/1
20 mg/1
Granular Activated Carbon:
~Per cent removals listed have been experienced for 2, 4,
5-T and are predicted for 2, 4, 5-TP (Silvex).
3. Turbidity •
Turbidity levels of more than 1 to 5 turbidity units may cause
interference with disinfection processes. This is the major reason for the
maximum contaminant levels of one turbidity unit (monthly average) and five
turbidity units (two-day average) as stated in the National Interim Primary
Drinking Water Regulations. At the discretion of the State, a maximum of five
turbidity units (monthly average) may be allowed if the water supplier can
demonstrate that the higher turbidity does not do any of the following:
(a)	Interfere with disinfection.
(b)	Prevent maintenance of an effective disinfectant agent throughout the
distribution system.
(c)	Interfere with microbiological determinations.
High turbidity can cause consumers to question the safety of drinking the
Turbidity in water may result from suspended and colloidal matter from a
variety of sources. It may be caused by microorganisms: mineral substances;

clay or silt and other products of natural erosion; domestic sewage or industrial
wastes; and others.
Treatment methods effective for turbidity reduction include various
combinations of the processes listed in Table 14.13]
Table 14
Unit Process	Per Cent Removal
Plain Sedimentation	50—95
Coagulation, Sedimentation,
and Filtration	80—99
4. Coliform Organisms
It is of the utmost importance that no pathogenic bacteria be present in
water intended for human consumption. Direct testing for pathogenic bacteria
is difficult and time-consuming, so an indirect test is utilized. A determination
is made of the presence of coliform bacteria. Although coliform bacteria are
usually nonpathogenic, under certain conditions strains of E. coli are capable of
causing disease. Under most circumstances, there are probably several thousand
coliform bacteria present for each pathogenic organism in contaminated water.
Therefore, if coliform bacteria are eliminated from a water, there should be
little concern about the water's safety from a bacteriological standpoint.
Presence in drinking water of any members of the coliform group indicates
deficiencies in treatment of the water.
The National Interim Primary Drinking Water Regulations do not contain
a single number as a limit for coliform bacteria. Maximum contaminant levels
for coliform bacteria have been established based on the frequency of sampling
and the type of test. Refer to Appendix A for coliform bacteria maximum
contaminant levels and monitoring frequency. The minimum number of
coliform test samples per month depends on the population served by the
water system; the larger the population, the greater the number of samples

required. The range is from a minimum of one per month for a community
system which serves a population of 25 up to 11 per month for a system which
serves a population of 10,000.
Is	'
The membrane filter technique is generally the recommended test method.
However, turbidity may interfere with the membrane filter technique, and the
multiple tube fermentation technique may have to be employed. When the
membrane filter test is used for a facility serving a population of 25 to 10,000,
the maximum number of coliform bacteria shall not exceed any of the
(a)	One per 100 ml as the arithmetic mean of all samples examined per
(b)	Four per 100 ml in more than one sample per month when less than
20 samples are examined per month. •
(c)	Four per 100 ml in more than five per cent of the samples when 20
or more are examined per month.
If the multiple tube fermentation technique is used, two standard portion sizes
may be used in the test. When 10 ml standard portions are used, coliform bac-
teria shall not be found in any of the- following;
(a)	More than 10 per cent of the portions in any month.
(b)	Three or more portions in more than one sample when less than 20
samples are examined per month.
(c)	Three or more portions in more than five per cent of the samples
when 20 or more samples are examined per month.
When 100 ml standard portions are used, coliform bacteria shall not be found
in any of the following:
(a) More than 60 per cent of the portions in any month.
,(b) Five portions in more than one sample when less than five samples
are examined per month.

(c) Five portions in more than 20 per cent of the samples when five or
more samples are examined per month.	v ;
Bacteria in water. sources are primarily the result of organic waste
pollution. Sources of this waste include decaying vegetative matter, decaying
animal wastes, wastes from food processing plants, untreated sewage and others.
In addition to direct contamination, bacteria may be transported to water by
air dispersion, birds, and other animals including man.
Disinfection is the primary process for the elimination of bacteria from
water. This and other methods of bacterial reduction are listed in Table 15.[3]
Table 15
Unit Process	Per Cent Removal
Chlorination	99
Ozonation	99
Chlorine Dioxide	99
Sedimentation*	0-99
Coagulation*	Significant amounts
Filtration*	0-99
*These methods do not, in themselves, provide adequate
bacterial reduction. However, their use prior to disinfec-
tion may significantly lower the costs associated with
5. Radiological
Any dose of ionizing radiation may produce harmful effects to human
health. Both short term and long term damage to human tissue may result from
radioactive contamination. Even if exposure is slight, there may be genetic-
changes or a cancer may develop.

Radioactivity in public water systems may be generally grouped as
naturally -occurring' or man-made. Radium-226 is the most important of the
naturally occurring radionuclides likely to occur in public water 'systems.
Radium is distributed throughout the United States, particularly in midwestern
and Rocky Mountain states. Usually found only in ground water, radium may
occasionally be found in surface water due to man's activities. In contrast to
radium, man-made radioactivity usually occurs in surface water. Sources of
man-made radioactivity, in addition to fallout from nuclear weapons testings,
are small,, releases from nuclear power plants, hospitals, and scientific and
industrial users of radioactive materials. Maximum contaminant levels for
radioactivity in water supply systems are summarized in Table 16.[3] Refer to
Appendix A for the radionuclide regulations as published in the Federal
Register. ¦
Table 16
Maximum Allowable
Constituent	Level
Combined radium—226 and radium—228	5 pCi/1
Gross alpha particle activity
(including radium—226 but excluding
radon and uranium)	15 pCi/1
Beta particle and photon radioactivity
from man-made radionuclides*	4 mrem/yr
•Based on a 2 liter per day drinking water intake except for tritium and
¦ strontium -90. Average annual concentrations of tritium and strontium -90
assumed to produce a dose of 4 mrem/yr are 20,OCX) and 8 pCi/I, respectively.
Virtually all water sources contain radium, a product of uranium, in trace
amounts. Studies indicate the occurrence of radium-226 in United States
treated water supplies ranges from 0.0 to 135.9 pCi/1. [2 J Also important in
health considerations, strontium -90 concentrations in public water supplies are
about 1.0 pCi/1. based on available data. Remedial measures for excessive
radioactivity in drinking water supplies include dilution of the contaminated
water, change of source, and treatment of the contaminated water. If treatment

for removal of radionuclides is necessary, conventional methods are usually
effective'. Listed in Table 17 [5]are various radionuclides and their removal
methods and efficiencies.
Table 17
Radionuclide	Removal Method	Per Cent Removal
Radium Ion Exchange Softening	70-98
Coagulation, Sedimentation,
and Filtration	25
Lime or Lime-Soda Softening	70—90
Reverse Osmosis	95
Beta and Photon Emitters* Lime Softening	87—96
Ion Exchange Softening	75—96
Reverse Osmosis	90—97
"Removal dependent on specific radioisotope present.
6. Stabilization
While stabilization of water is not directly addressed in the Interim
Primary Drinking Water Regulations, it is implied because the maximum
contaminant levels for inorganic chemicals are at the consumer's tap. Thus, if
the water leaves the treatment plant with all contaminants below their
respective maximum contaminant levels, but samples from the distribution
system show values above those maximum contaminant levels, then the water
quality is in violation of, the regulations. Corrosive water can cause
solubilization of certain contaminants listed in the Interim Primary Drinking
Water Regulations.
Cadmium is present in zinc-galvanized iron pipe and may be dissolved by .
corrosion. Corrosive water standing in lead pipes can, under certain conditions,
solubilize enough lead to exceed the MCL.

• A noncorrosive water may be maintained throughout the distribution
system -in two ways: (1) by maintaining calcium carbonate saturation
equilibrium with appropriate pH control, and (2) by introducing additives such
as phosphates or silicates. In both cases, a thin protective film is formed on the
interior of the piping, thus protecting it from corrosion,
While primary regulations apply to trace elements, compounds, and
microoganisms affecting the health of consumers, secondary regulations deal
with: the aesthetic qualities of drinking water. The contaminants included in
these secondary regulations do not have a direct impact on the health of
consumers. However, if present in excessive amounts, these contaminants may
affect the palatability of the water and encourage the use of possibly unsafe
In contrast to primary drinking water regulations, the secondary
regulations are not Federally enforceable. As guidelines for suppliers of water,
these regulations are meant to be used to improve the quality of water
delivered. The secondary drinking water regulations contain recommended
maximum contaminant levels for various inorganic chemicals and physical
quality characteristics of drinking water. The USEPA has published Proposed
National Secondary Drinking Water Regulations (Federal Register, Vol. 42,
No. 62, March 31, 1977, see Appendix B). The following substances are
1. Chloride
Chloride in concentrations above 250 mg/1 causes a salty taste in water
which is objectionable to many people.[ 11 ] In addition to adverse taste effects,
significant increases in customer costs due to deterioration of plumbing and
water heaters may be encountered at chloride levels of 500 mg/1. Excessive
chloride levels are most often found in highly mineralized ground water. The
occurrence of chloride in United States drinking water supplies ranges from 1

to 1.950 rag/1.[2] Chloride	is not significantly affected by conventional
treatment processes. Reverse	osmosis or electrodialysis can effectively remove
chloride from drinking water.	;
.	H
2. Color
Color in drinking water becomes objectionable and unaesthetic to most
people at levels above 15 color units. [ 11 ] The level of this substance does not
directly indicate the safety of a drinking water supply. However, highly colored
water indicates the potential presence of industrial or domestic wastes as well
as mineral or organic materials. Iron and manganese compounds are minerals
which can impart undesirable colors to water. Humus, peat, algae, weeds and
protozoa are examples of organics which contribute color to water. Some
industries whose processes generate color are mining, explosives production,
refining, pulp and paper manufacture, and chemical production.
Selection of a treatment method for removal of color is dependent on the
nature of the substances causing the color. Treatment methods and removal
efficiencies are listed in Table 18.[3]
Table 18
Unit Process*	Per Cent Removal
Coagulation	95
Filtration	50—95
Reverse Osmosis 99
Ion Exchange 100
Activated Carbon 100
•Additional process information is included in the
following text.
With alum coagulation the best removal is usually achieved with a pH
range of 4 to 6.[2] However, for minimum solubility of the coagulant, the pH

should be adjusted to greater than 6 prior to filtration. Color coagulation can
also be achieved with magnesium hydroxide at a pH greater than 11.0. The per
cent removal stated in Table 18 for reverse osmosis applies to all color
producing materials with molecular weights greater than 200. Ion exchange, as
listed in Table 18. applies to the use of special resins for the removal of organic
dye wastes, humates and ligates. The per cent removal listed for activated
carbon in Table 18 is for noncolloidal, soluble, aromatic-structured color
3.	Copper
The proposed maximum contaminant level of 1.0mg/l for copper was
recommended because copper imparts an undesirable taste to drinking water.
Large doses of copper may produce nausea and prolonged ingestion may result
in liver damage.[ 11 ] Small amounts of copper, however, are generally
considered nontoxic. In fact, copper is an essential element in human
In water supplies tested across the United States, copper was found in
concentrations ranging from 0.0 to 8.35 mg/1. [ 21 Copper occurs naturally in
surface waters. Other sources of copper pollution include the corrosive action
of water in copper and brass tubing, industrial effluents and the use of copper
compounds for control of algae. Copper salts are used in fungicides, insecticides
and various industrial processes -such as textile manufacture, tanning,
photography, and electroplating.
Removal of copper from drinking water supplies can be accomplished by
the treatment methods listed in Table 19,[3]
4.	Corrosivity
Corrosion causes various problems in the water distribution system,
including tuberculation, leaks, main ruptures, discoloration and loss of chlorine
residual. Corrosion is also responsible for an increase in concentrations of trace
metals, such as lead, cadmium, iron and copper, as the corrosion damages
service lines and household plumbing.

Table 19
Unit Process	Per Cent Removal
Coagulation, Sedimentation,
and Filtration	*
Softening	*
Reverse Osmosis	90-97
Electrodialysis	80
Ion Exchange	95
Stabilization**	100
*Will reduce copper centration below MCL. [12]
""Applies only to prevention of corrosion of copper piping
materials in the distribution system.
Corrosivity is related to pH, alkalinity, dissolved oxygen, total dissolved
solids and other factors. Therefore a straight-forward maximum contaminant
level has not been proposed.
The adverse effects of corrosion are primarily economic. Therefore, the
cost of corrosion control could be offset by the savings from damage
prevented. Refer to section III A6, Stabilization for a discussion of methods
for controlling corrosion.
5. Foaming Agents
Foaming is an undesirable property of drinking water because it is
aesthetically displeasing and is often associated with contamination. Many
substances in water will cause foam when the water is agitated or air is
entrained. The major class of substances which produce foaming is the anionic
surfactant. Contamination of drinking water supplies by this surfactant results
from household and industrial synthetic detergent pollution.

Concentrations of anionic surfactants found in drinking waters have ranged
from 0 to. 2.6 mg/1 in well water supplies and from 0 to 5 mg/1 in surface water
supplies. [ 11] A proposed maximum contaminant level of 0.5 mg/1, as
methylene blue, active substances, was chosen to prevent the occurrence of
visible foam. The treatment method for removal of foaming agents is
adsorption by activated carbon. Removal efficiency ranges from 90 to 100 per
cent [3]
6.	Hydrogen Sulfide
Hydrogen sulfide in drinking water often produces very obnoxious odors
characteristic of "rotten eggs". Corrosion of ferrous metals in well pump
assemblies and filters and corrosion of concrete holding and distribution
facilities occurs when hydrogen sulfide levels exceed 0.5 mg/1. [11] Hydrogen
sulfide is often caused by microbial action on organic matter or reduction of
sulfate ions to sulfide by bacteria and can be found in both ground and surface
waters. In addition to its offensive odor and corrosive tendencies, hydrogen
sulfide in association with soluble iron produces black stains on laundered items
and black deposits on piping and fixtures.
Hydrogen sulfide odor is usually identifiable at concentrations of a few
hundredths of a milligram per liter. The proposed maximum level for hydrogen
sulfide is 0.05 mg/1. Treatment methods for removal of hydrogen sulfide from
drinking water include aeration, which is usually not sufficient by itself,
followed by chemical oxidation. For waters with a constant hydrogen sulfide
odor, aeration may produce a fine elemental sulfur precipitate which will
require coagulation, sedimentation and filtration for removal.
7.	Iron
Iron is a highly objectionable constituent of water supplies. It may impart
brownish discolorations to laundered goods or a bitter or astringent taste to
water. The proposed maximum level of iron in drinking water is 0.3 mg/1.
Normal diets contain 7 to 35 mg per day and average 16 mg.[ 11 ] Therefore,
the amount of iron permitted in water is small compared to the amount

normally consumed and does not have toxicological significance. Sources of
iron pollution include iron-bearing ground water, acid mine drainage,
iron-bearing industrial wastes and corrosion of iron and its alloys. The
concentration of iron in .well-aerated. surface water is usually low. Treatment
methods for iron removal are listed in Table 20.[3]
Table 20
Unit Process	Per Cent Removal
Reverse Osmosis
Ion Exchange
Diatomite Filtration
Coagulation, Sedimentation,
and Filtration
'Additional process information is included in the
following text.
**Applies only to prevention of corrosion of iron piping
materials in the distribution system.
***Will reduce iron concentration below MCL. [12]
* **
For a detailed discussion of oxidation methods for. iron removal, refer to
section IV A2, Oxidation. Diatomite filtration can lower iron levels to 0.1 mg/1,
if accompanied by preaeration and alkalinity adjustment. [3]
8. Manganese
As for iron, the principal reason for. limiting this element is to prevent
brownish stains in laundered goods and adverse taste effects in drinking water.
From the health standpoint, there are no data to indicate at what level

manganese would be harmful when ingested; the daily intake of manganese
from a normal diet is about 10 mg. [11]
Manganese concentrations in well-aerated surface waters are rarely over
1.0 mg/l.[3] Deep reservoirs can have undesirable concentrations of manganese
in lower portions of the reservoir where reducing conditions prevail. This
manganese can cause problems if the water supply intake is located in the deep
portion of the reservoir or can cause problems for higher intakes during
turnover.* In ground water with reducing conditions, high concentrations of
manganese may be leached from mineral deposits. Manganese frequently
accompanies iron in such ground waters. In addition, manganese is used in the
manufacture of paints, steel, glass, and various other materials. It is also used in
agriculture to enrich manganese deficient soils and may enter water supply
sources through runoff.
The proposed maximum contaminant level for manganese is 0.05 mg/1.
Applicable unit processes for removal of manganese are shown in Table 21.[3]
Table 21
Unit Process	Per Cent Removal
Reverse Osmosis
Ion Exchange
Diatomite Filtration
•Additional process information is included in the follow-
ing text,
"•Will reduce manganese concentration below MCL. [12]

For a detailed discussion of oxidation methods for manganese removal,
refer to section IV A2, Oxidation. Manganese removal, with preoxidation, to
0.05 mg./l is possible with diatomite filtration.[3]	1
9.	Odor
Odor is an important aesthetic quality of water for domestic use. It is
impractical and often impossible to isolate and identify the odor-producing
chemical. Therefore, the senses of smell and taste are used to evaluate odors
and tastes. In most cases, sensations ascribed to the sense of taste are actually
Undesirable odors in water are caused by vapors from various chemicals
including halogens, sulfides, ammonia, turpentine, phenols, cresols, picrates,
various hydrocarbons and unsaturated organic compounds. Natural waters may
be contaminated with odor producing compounds from weeds, bacteria, fungi,
actinomycetes, algae and decaying animal matter. Sewage and industrial wastes
may also contribute odorous compounds to water supplies. In addition, some
inorganic substances, such as metal ions, impart taste and odor to water.
The proposed maximum contaminant level for odor is a Threshold Odor
Number (TON) of 3. For water, the TON is the dilution factor required before
the odor is minimally perceptible. Treatment methods for odor removal include
aeration, activated carbon, ozonation, superehlorination, chlorine dioxide, and
potassium permanganate. Laboratory tests are required to determine the removal
effectiveness of each unit process.
10.	pH
The proposed range for pH has been set at 6.5 to 8.5, the lower level to
prevent appreciable corrosion and the higher level to prevent encrustation, taste
and reduced chlorine efficiency. However, the impact of pH in any one water
system will vary with the overall chemistry of the water. Thus, a higher or
lower pH range may be appropriate under specific conditions. Midwest waters,
for example, are usually adjusted during softening to one pH unit above the
Langelier stability pH, usually in the low 9's. Chemical addition of lime, soda

ash or caustic soda is used to increase pH of a water supply; to decrease ,pH,
carbon dioxide, sulfuric acid or hydrochloric acid may be added during the
treatment process.
11. Sulfate
At concentrations above 250 mg/1. sulfates create taste problems; above
600 mg/1, they may have a laxative effect. [11] In addition, high
concentrations of sulfate contribute to the formation of scale in boilers and
heat exchangers.
Sulfates may enter water sources from tanneries, sulfate-pulp mills, textile
mills, and other plants that use sulfate or sulfuric acid. Leachings from gypsum
and other common minerals may contaminate sources of water supply. Also,
oxidation of sulfides, sulfites, and thiosulfates in surface water yield sulfates.
Concentrations of sulfates in United States water supplies range from less
than 0.1 to 770 mg/1.[2] The proposed maximum level of sulfate is 250 mg/1.
Treatment methods for sulfate are listed in Table 22. [3]
Table 22
Unit Process	Per Cent Removal
Reverse Osmosis	99
Electrodialysis •	80
Ion Exchange	95
12. Total Dissolved Solids (TDS)
TDS may influence the acceptability of water and a high concentration is
often associated with excessive hardness, taste, mineral deposition or corrosion.
The proposed MCL for TDS is 500 mg/1. Applicable treatment methods for
TDS removal are listed in Table 23 .[13]

Table 23
Unit Process*
Per Cent Removal
Chemical Softening
Reverse Osmosis
Ion Exchange
up to 99
* Additional process information is included in the following texl.
**See text.
The TDS removal by chemical softening is dependent upon the amount of
hardness removed and the relationship between hardness and TDS in the raw
water. A recent publication [ 14] recommended that ion exchange be
considered for TDS removal if the maximum raw water TDS concentration is
less than 2,000 rng/1. Similarly, the application range for electrodialysis and
reverse osmosis is a TDS concentration of 1,000 to 5,000 mg/1 and 1,000 to
10,000 mg/1, respectively. If the maximum TDS level falls within the range of
more than one of these processes. 1,500 mg/1 for example, then an economic
comparison should be used to select a specific treatment method.
Zinc is an essential and beneficial element in human metabolism; the daily
adult human intake averages 10—15 mg.[ 11 ] Zinc in water does not cause
serious adverse health effects but does produce undesirable aesthetic effects. At
concentrations of 5 mg/1, zinc can impart an objectionable taste to water.
Soluble zinc salts, at 30 mg/1, give a milky appearance to water and at 40 mg/1,
they impart a metallic taste.
industrial uses of zinc salts which may contaminate water sources include
the manufacture of dyes, pigments, insecticides and the galvanizing process.
13. Zinc

Zinc is rarely found above the trace level in natural waters. Zinc has been
found to occur in United States water supplies in concentrations ranging from
Oto 13 mg/l,[2J The proposed maximum level of zinc is 5 mg/1. Unit processes
applicable for zinc removal are shown in Table 24. [3]
Table 24
Unit Process	Per Cent Removal
Reverse Osmosis
Ion Exchange
•Applies prevention of corrosion of zinc piping
materials in the distribution system.
**Will reduce zinc concentration below MCL. [12]

1.	U.S. Environmental Protection Agency, Statement of Basis and Purpose
for the National Interim Primary Drinking Water Regulations.
2.	Floyd B, Taylor, "Trace Elements and Compounds in Waters," Jour
A WW A, 63(1l);728-733 (November, 1971).
3.	David Volkert and Associates, Monograph of the Effectiveness and Cost of
Water Treatment Processes for the Removal of Specific Contaminants,
68-01-1833, U.S. Environmental Protection Agency (August, 1974).
4.	Ervin Bellack, "Arsenic Removal from Potable Water," Jour AWWA,
63(7):454-458 (July, 1971).
5.	U.S. Environmental Protection Agency, Manual of Treatment Techniques
for Meeting the Interim Primary Drinking Water Regulations, May, 1977.
6.	G. F. Craun and L. J. McCabe, "Problems Associated with Metals in
Drinking Water," Jour A WWA, 67(11):593-599 (November, 1975).
7.	American Water Works Association, Water Quality and Treatment,
3rd edition, McGraw-Hill, New York. 1971.
8.	R, D. Scott, et al, "Fluorides in Ohio Water Supplies," Jour AWWA,
29(9):9-25 (September, 1937).
9.	L. J. McCabe, et al, "Survey of Community Water Supply Systems," Jour
AWWA, 62(11):670 (November, 1970).
10.	Illinois Environmental Protection Agency, Determination of Radium
Removal Efficiencies in Water Treatment Processes for Small and Large
Populations, USEPA (May. 1976).
11.	U.S. Environmental Protection Agency, Statement of Basis and Purpose
for the Secondary Drinking Water Regulations.
12.	Y. H. Lin and J. R. Lawson, "Treatment of Oily and Metal-Containing
Wastewater ."Pollution Engineering, 5( 11):47 (November, 1973).

REFERENCES (Continued)
13.	Black & Veatch, Water Management Guidelines for Saudi Arabian Military
Installations, U.S. Army Corps of Engineers (January, 1977).
14.	U.S. Department of the Interior, Office of Saline Water and U.S. Bureau
of Reclamation, Desalting Handbook for Planners, 1972.

American Water Works Association, Water Quality and Treatment, 3rd edition,
McGraw-Hill, New York, 1971.
Bellack, Ervin, "Arsenic Removal from Potable Water," Jour AWWA,
63(7):454-458 (July, 1971).
Black & Veatch, Water Management Guidelines for Saudi Arabian Military
Installations, U.S. Army Corps of Engineers, January, 1977.
Clark, Viessman and Hammer, Water Supply and Pollution Control, 2nd edition,
International Textbook, Scran ton, 1971.
Craun, G. F. and McCabp, L. J., "Problems Associated with Metals in Drinking
Water," Jour AWWA, 67(11):593-599 (November, 1975).
Culp, Gordon L. and Gulp, Russell L., New Concepts in Water Purification, Van
Nostrand, New York, 1974.
David Volkert and Associates, Monograph of the Effectiveness and Cost of
Water Treatment Processes for the Removal of Specific Contaminants,
68-01-1833, U.S. Environmental Protection Agency, August, 1974.
Lin, Y. H. and Lawson, J. R., "Treatment of Oily and Metal-Containing
Wastewater," Pollution Engineering, 5(11):47 (November, 1973).
McCabe, L. J., Et Al, "Survey of Community Water Supply Systems," Jour
AWWA, 62(11):670 (November, 1970).
Taylor, Floyd B., "Trace Elements and Compounds in Waters," Jour AWWA,
63(11):728-733 (November, 1971).
U.S. Department of the Interior, Office of Saline Water and U.S. Bureau of
Reclamation, Desalting Handbook for Planners, 1972.
Scott, R. D., et al, "Fluorides in Ohio Water Supplies," Jour AWWA,
29(9):9-25 (September, 1937).

U.S. Environmental Protection Agency, Manual of Treatment Techniques for
Meeting the Interim Primary Drinking Water Regulations, May, 1977.
U.S. Environmental Protection Agency, Statement of Basis and Purpose for the
National Interim Primary Drinking Water Regulations.
U.S. Environmental Protection Agency, Statement of Basis and Purpose for the
Secondary Drinking Water Regulations.
Weber, Walter J., Physicochemical Processes for Water Quality Control,
Wiley-Interscience, New York, 1971.

Various types and combinations of treatment units are used to produce
water suitable for human use. The quality of the source and the quality goals
for the finished water form the basis for selecting a method of treatment.
Finished water quality goals are given in the preceding section; the means of
achieving them will be discussed subsequently.
Selection of water treatment processes is based on the contaminants to be
removed. A variety of unit processes may be required for treatment of the
contaminants listed in Section III. Necessary unit processes are generally the
same for large or small treatment plants, only scaled down for small facilities.
Exceptions to this general rule are discussed where this is not true and a
recommendation is given as to the process most applicable to small water
treatment systems, This section will, therefore, emphasize the unit processes
specifically applicable to water treatment systems serving a population of 25 to
10,000. All design parameters are in terms of plant capacity as opposed to
average daily flow.
1. Aeration
As applied to water treatment, the term aeration refers to processes by
which water and air are brought into contact with each other for the purpose
of transferring volatile substances to or from the water. These volatile
substances include oxygen, carbon dioxide, nitrogen, hydrogen sulfide, methane
and unidentified organic compounds responsible for tastes and odor. Aeration is
not needed at all water treatment plants and a decision as to whether to aerate
or not requires careful assessment of the economic and water quality benefits
achieved by its use.
The water source is an important selection factor. Surface waters usually
exhibit low concentrations of carbon dioxide, no hydrogen sulfide and fairly

high dissolved oxygen. Consequently, aeration is not required for the removal
or addition of these gases. However, many surface waters do contain traces of
volatile organic substances that cause taste and odor problems. While the
aeration process is a means of volatile organic matter reduction, conventional
aeration systems are not particularly effective because of the low volatility of
most taste-and-odor producing compounds. Aeration of surface waters usually
cannot be justified on economic grounds.
Ground waters may contain excessive carbon dioxide, methane, hydrogen
sulfide, iron, or manganese concentrations. At lime-soda water softening plants,
any carbon dioxide dissolved in the water at the point of lime application will
consume lime without accompanying softening. For high (>50 mg/1) carbon
dioxide concentrations, as encountered in some ground waters, aeration for its
removal is probably justified. For concentrations on the order of 10 mg/1 or
less, aeration is probably not economically valid. Before a decision to aerate for
carbon dioxide removal, the cost of maintaining and operating the aerator
should be compared to the value of the lime saved and the additional sludge
disposal cost.
Aeration will remove methane, a potentially explosive gas sometimes
encountered in fairly high concentrations in ground water. Methane removed in
appreciable quantities can pose an explosion hazard unless properly disposed.
Aeration is often used for removing hydrogen sulfide from water. It is
effective if the hydrogen sulfide concentration is not more than about 1.0 or
2.0 mg/1. Higher concentrations may require special provisions, such as
prolonged aeration with diffused air or initial aeration in an atmosphere
containing a higher than normal concentration of carbon dioxide followed by a
standard aeration process. Such an atmosphere reduces pH, thus releasing the
H2S form of the sulfide and promotes its removal by aeration.
Ground waters are usually deficient in oxygen and aeration is an effective
means of adding it. Oxygen addition is desirable if iron and manganese removal
is a treatment objective. This is discussed in detail in section IV A2, Oxidation.
The three methods of aeration employed in small water systems
are a) gravity, b) mechanical draft, and c) diffused aeration.

a.	Gravity Aeration. Various types of gravity aerators have been used in
the water treatment industry. The most practical method of gravity aeration for
small water treatment systems consists of a stack of multiple trays which are
often filled with contact media. Water flows by gravity over the layers of media
and trays. The use of mechanical draft aeration with this method of gravity
aeration is discussed in the following subsection. Information on media and trays
is also included.
b.	Mechanical Draft Aeration. This aeration system consists of a tower
through which water droplets fall and air ascends in countercurrent. flow. The
tower usually is made up of a series of trays with wire-mesh, slat or perforated
bottoms over which the water is distributed. In most aerators, coarse media
such as coke, stone or ceramic balls 5 to 15 cm (2 to 6 in) in diameter are
placed in the trays to increase efficiency. Coarse media are especially efficient
when the removal of iron and manganese is of importance. The media becomes
coated with precipitated oxides of iron and manganese, which serve as catalysts
for continuing oxidation reactions. A small basin is often constructed below the
aeration unit to allow entrained air to dissipate. The depth of this basin is
usually 1.8 m (6 ft); the width and length are frequently the same as those of
the aeration unit in question.
Design criteria for mechanical draft aerators are dependent on the type
and concentration of the contaminant involved. In aeration towers, five to
fifteen trays spaced vertically 30 to 76 cm (12 to 30 in) apart are frequently
used. Area requirements for the trays vary from 5.6 to 17.9 cm" per m /day (23
to 73 ft^ per mgd); most require less than 7.3 cm^ per m^/day (30 ft^ per
mgd). Selection of specific design criteria is usually a joint decision by the
manufacturer and engineer. Mechanical draft aeration equipment, of interest for
this report, is available in various capacities ranging from 218 to 5,450 m /day
(40 to 1,000 gpm).
c.	Diffused Aeration. Diffused aeration units generally consist of
rectangular basins with d iff user equipment located near the bottom. The
diffusers distribute compressed air into water through orifices or nozzles in air
piping, diffuser plates or tubes. Basins are frequently 2.7 to 4.6 m (9 to 15 ft)
deep and 3.1 to 9.2 m (10 to 30 ft) wide. Ratios of width to depth should not
exceed 2:1 to insure effective mixing. The length of the basin is governed by
the desired retention period, usually 10 to 30 minutes.

The amount of air required depends on the purpose, of aeration, but
generally ranges from 0.075 to 1.12 m^ of air per (0.01 to 0.15 fP of air
per gal) of water treated.	.	- . ..
Diffused air treatment units conserve the hydraulic head and are not
subject to freezings but require more space than tray aerators. To prevent odor
problems, both types of aeration may require housing if hydrogen sulfide is
being removed.	'
d. Applicability and Recommendations. Aeration is recommended as a
treatment process for carbon dioxide, hydrogen sulfide, and odor removal and
as an aid in iron and manganese removal. The decision to use aeration as a
treatment process and selection of the type of aeration to employ must be
based on the quality of the source of water supply and the contaminants to be
removed. An economic analysis should be made to decide between gravity,
mechanical draft, and diffused aeration. Mechanical draft aeration is limited in
applicability to the sizes of aerators manufactured. Diffused* aeration is
generally not economically desirable for small water treatment systems.
However, if diffused aeration can also serve as a chemical mixing unit as well as
an aeration system, then the economics may favor this system.
2. Oxidation
Water treatment utilizes oxidation for various purposes. A number of
oxidants can be used to remove or destroy undesirable tastes and odors, to aid
in the removal of iron and manganese, and to help improve clarification and
color removal. Oxygen, chlorine, and potassium permanganate are the most
frequently used oxidizing agents and each is discussed in following sections.
a. Air. Aeration is used as a method of adding oxygen to water for
oxidation of iron and manganese. For precipitation of 1 mg/1 of iron," 0.14 mg/1
of oxygen is required, and 0.24 mg/1 of oxygen is required for precipitation of
1 mg/1 of manganese. Soluble iron is readily oxidized by the addition of oxygen,
but manganese cannot be oxidized as easily. However,'oxidation of manganese
'is encouraged if the aeration step provides contact between water and previously
precipitated manganese oxide, such as occurs in certain gravity and mechanical

draft aerators. Media in these units become manganese-coated and catalytic
oxidation of manganese occurs, particularly when the pH has been increased to
greater than 8.5, If the level of manganese to be removed is high, aeration
processes are usually designed to only initiate oxidation of the manganese. More
effective chemical oxidation is then used to achieve acceptable levels of man-
Oxidation of organic substances responsible for undesirable tastes and
odors using aeration is usually too slow to be of value. However, if dissolved
gases such as hydrogen sulfide are the cause of taste and odor problems,
aeration will effectively remove them through oxidation and stripping.
b. Chemical. Oxidizing chemicals commonly used in water treatment
include chlorine, chlorine dioxide, ozone and potassium permanganate. Chlorine
and potassium permanganate are the most frequently used chemical oxidants.
Ozone and chlorine dioxide require on-site generation and are relatively
expensive. Compared to air, chemicals are much stronger oxidizers, therefore
more effective. The respective costs for aeration versus chemical oxidation must
be compared with the benefits received before a choice of which process to use
can be made.
Chlorine, chlorine dioxide and potassium permanganate act effectively as
oxidizing agents in destroying taste and odor producing compounds. They also
readily oxidize soluble iron and manganese to insoluble oxides. The oxides of
iron and manganese are then removed by coagulation, sedimentation and
filtration. Difficulties with clarification or color removal which may arise from
dissolved organic compounds often can be reduced by the use of chlorine,
chlorine dioxide and potassium permanganate. They are added to oxidize
interfering organic matter.
Although relatively effective for iron oxidation, chlorine requires longer
contact time than potassium permanganate to effectively oxidize manganese at
levels greater than 0.2 mg/1. Theoretical amounts of chlorine required are
0.64 mg/1 per 1.0 mg/1 of iron and 1.3 mg/1 per 1.0 mg/1 of manganese. In
practice, higher values are used to increase the rate of reaction and provide
chlorine for competing reactions. The rate of manganese oxidation by chlorine
is dependent on pH, chlorine dosage, mixing conditions and other factors. High
pH values favor oxidation of manganese.

One main advantage of potassium permanganate oxidation is the high rate
of reaction, many times faster than chlorine. Also, potassium permanganate
differs from chlorine in that it does not form additional products that might
intensify odors normally present. Potassium permanganate is not as pH
dependent as chlorine, although the permanganate does react more rapidly as
pH increases. Theoretically, 0.94 mg/1 of potassium permanganate will oxidize
].0mg/l of iron,and 1.92 mg/1 of potassium permanganate will oxidize 1.0 mg/1
of manganese. In actual practice, the amount of permanganate required is
usually less than the theoretical amount. One method of determining the
optimum dose of permanganate is to observe the color of the water after
application of the oxidant. If a slight pink color persists for a minute or two,
the dose is said to be optimum.
As these oxidation processes .are not instantaneous, it is desirable to add
the oxidant, whether chlorine, chlorine dioxide or potassium permanganate, as
early as possible in the treatment process. Early addition of chlorine in the
treatment process is inconsistent with prevention of trihalom ethane formation;
therefore, KMn04 may be the oxidant of choice. The decision whether to use
chlorine or potassium permanganate for oxidation purposes must be based on
the contaminant to be removed, on an economic evaluation of the chemicals,
and tendencies toward trihalom ethane formation.
A method used for removal of iron and manganese is application of
potassium permanganate and filtration through manganese dioxide greensand.
Greensands are naturally occurring silicates of sodium and aluminum.
Manganese dioxide, an oxidizing agent, is affixed to the greensand, and water
containing iron and manganese is passed through this material The manganese
dioxide oxidizes the iron and manganese to insoluble forms which precipitate
onto the greensand filter. After the oxidizing capacity of manganese dioxide
greensand has been depleted, it is regenerated with potassium permanganate. A
modification to this process has been developed wherein the manganese dioxide
is continuously regenerated with potassium permanganate.. Potassium perman-
ganate is continuously fed to the water before entering the filter. The iron and
manganese are oxidized by the potassium permanganate and precipitated on the
filter. If too little potassium permanganate is added, the iron and manganese
are oxidized by the manganese dioxide affixed to the greensand; if too much
potassium permanganate is added, the manganese dioxide greensand is
regenerated. Thus, uniform amounts of potassium permanganate may be added

to a water containing varying concentrations of iron and manganese. Where
greensand filtration is preceded by aeration, the amount of precipitated iron
influent to the greensand filter can be large. When this situation exists, a layer
of crushed anthracite coal on top of the exchange medium is sometimes used
to prolong filter runs.
c. Applicability and Recommendations. For small water treatment
systems, it is recommended that chlorine be considered before other oxidants
since chlorine will normally be used for disinfection, too. If the use of chlorine
for oxidation would not be practical, then the use of air or potassium
permanganate should be evaluated on an economic basis. Generally, aeration is
preferred to use of potassium permanganate for oxidation unless high levels of
manganese are to be removed. In that case, the use of potassium permanganate
is necessary. Also, if intermittent tastes and odors are a problem, potassium
permanganate is preferred economically to aeration. Chemical feed equipment
requires a smaller capital expenditure than aeration equipment. In addition, the
chemical oxidant would be used on an intermittent basis so operation and
maintenance costs would be at a minimum.
Oxidation is recommended as a treatment process for hydrogen sulfide
and odor removal, and as an aid in iron and manganese removal,
3. Adsorption
The most important direct applications of adsorption in water treatment
are the removal of arsenic, fluoride and organic pollutants. Basically, adsorptio"
is the attraction and accumulation of one substance on the surface of another.
Two important adsorptive media in the water industry are activated alumina,
often referred to as simply alumina, and activated carbon. Operational
characteristics and regenerative techniques will be discussed for both of these
adsorptive media.
a. Activated Alumina. Activated alumina is a highly porous and
granular form of aluminum oxide. This material is available from several
aluminum manufacturers in various mesh sizes and degrees of purity. Alumina
is used in the water treatment industry for removing arsenic and fluoride. The
treatment process consists of percolating water through a column of the
alumina media. Removal of arsenic and fluoride is accomplished by a
combination of adsorption and ion exchange.

An activated alumina column consists of alumina media in a contact tank.
Either gravity or pressure feed systems can be used. As far as is known, there is
very little difference between removal capabilities of these two systems. For
sizing the surface area of an alumina column, a surface loading rate of 150 to
175 m^/m^/day (2.5 to 3.0 gpm/ft^) is recommended. The volume, and thus
the depth, of media is influenced by the time between regenerations of the
alumina. It is advisable to carry out laboratory and pilot-scale studies on the
water in question to aid in actual design of the activated alumina column.
Use-.-.of the activated alumina process for the removal of arsenic and
fluoride from water is cyclic and regeneration of the alumina media is required
periodically. When the alumina columns become saturated with arsenic and
fluoride, they are regenerated by passing a caustic soda solution through the
media. Excess caustic soda is neutralized by rinsing the activated alumina with
an acid. Prior to the regeneration process, the alumina column is backwashed to
remove accumulated solids that have been strained from the water. Adequate
disposal of the regenerative chemical wash should be provided. One disposal
method which warrants consideration is lagoon evaporation. If permitted by
local conditions, neutralization of the regenerative chemical wash followed by
dilution and discharge to a sanitary sewer should also be considered. Possible
toxic effects of the removed arsenic and/or fluoride should be evaluated prior
to discharge to a sanitary sewer.
If treated water storage facilities are limited or if interruptions of other
treatment plant processes cannot be tolerated, the use of duplicate alumina
contact columns is recommended.
b. Activated Carbon. Adsorption of organic impurities using activated
carbon has been common practice in the waterworks industry for many years.
Activated carbon is especially effective as an adsorbing agent because of its
large surface area to mass ratio. Each activated carbon particle contains a
tremendous number of pores and crevices into which organic molecules enter
and are adsorbed to the activated carbon surface.
Activated carbon has a particularly strong attraction for organic molecules
and thus is well-suited for removal of hydrocarbons, control of taste and odor,
and color removal. At present, activated carbon has been used with only
limited success to remove haioform precursor compounds. Frequent regenera-

tion or replacement of the activated carbon would be required, as its
effectiveness in adsorbing precursor compounds is limited to only a few weeks
after being placed in use.
Excessive fluoride and un-ionized metals such as arsenic and mercury can
be removed from water by adsorption using bone char. However, if used for
arsenic removal, bone char cannot be regenerated and must be used on a
throw-away basis. .
Both the adsorptive and the physical properties of an activated carbon
medium are important. Currently, there is no direct method for determining
the adsorptive capacity of an activated carbon. Adsorptive capacities can be
approximated by the Iodine Number or the Molasses Decolorizing Index. The
Iodine Number indicates the capability of the activated carbon for removing
small molecules. The Molasses Decolorizing Index provides an indication of the
potential of the activated carbon for adsorbing large molecules.
Two types of activated carbon are used in water treatment: powdered and
granular.. Powdered activated carbon is often used for taste and odor control.
Its effectiveness depends on. the source of the undesirable tastes and;odors. This
type of activated carbon is a finely ground, insoluble black powder which can
be fed to water either with dry feed machines or as a carbon slurry. Slurry
methods are usually applicable only in large water treatment plants, therefore
will not be discussed here. The powdered carbon approach offers economic
advantages when a low or infrequent carbon usage is required to solve a specific
Powdered carbon may be added at any point in the treatment process
ahead of the filters. Actual application points vary depending on local
conditions and contaminants to be removed. Normally, application of carbon is
most effective where pH of the raw water is lowest. Adequate dispersion of the
carbon is necessary; therefore,a settling basin should not be used as a point of
application. Sufficient contact time is also necessary to ensure maximum
adsorption by the carbon. Periods of contact ranging from 15 minutes to one
hour are recommended; Powdered carbon should be applied prior to
chlorination. Compounds that have a chlorine demand will be removed by the
activated carbon; thus,* savings in chlorine will be realized. Also, activated
carbon will efficiently adsorb chlorine thus . wasting both the carbon and

Recent practice recommends the use of carbon for removal of taste and
odor producing organics prior to chlorination. This prevents the formation of
chloro-organics which are very difficult to remove by carbon. High doses of
carbon fed to the filter influent will cause rapid build-up of loss of head and
there is the hazard of carbon "bleed-through". Effluents must be carefully
monitored when carbon is fed to filter influent.
As a rough guide, dosages for taste and odor control vary from 2 to 8 mg/1
for routine continuous application. 5 to 20 mg/1 for intermittent severe
problems and 20 to 100 mg/1 for emergency treatment of chemical spills.
Powdered activated carbon has not been recovered and regenerated in the past.
Powdered activated carbon either settles out in the clarifier or is retained in the
filter. Spent carbon is then disposed of along with other plant waste solids.
Granular activated carbon, used as media in gravity filters, pressure vessels
and specially designed adsorbers, is effective for water treatment purposes.
Removal of organics and mercury is the primary use of granular activated
carbon. Activated carbon filters can be used either in place of, or in addition
to, conventional filters.
If activated carbon filters are used in place of conventional filters, special
care must be taken in the design and operation of filter cleansing facilities and
in the selection of activated carbon granule characteristics so that the filters can
be effectively backwashed without the loss of the carbon medium in the
backwash troughs.
The use of activated carbon filters has not been widely practiced in the
past, so optimum configurations and operating rules have not fully evolved.
Many of the guidelines given for conventional filters are also applicable to
activated carbon filters.
Filter depths generally vary from 0.8 to 3.0 m (2.5 to 10 ft), with an
activated carbon layer of 0.3 to *1.5 m (1 to 5 ft) overlying a layer of coarse
gravel above the underdrain system. An intermediate layer of sand, 15 to 46 cm
(6 to 18 in) is sometimes used between the activated carbon and the gravel.
Flow rates through the activated carbon filters are usually 120 to
300 m3/m2/day (2 to 5 gpm/ft2).

The activated carbon medium must periodically be replaced with new or
regenerated activated carbon. Replacement cycles can vary from 1 to 3 years
for taste and odor removal down to 3 to 6 weeks for removal of haloform
precursors. Regeneration involves (1) removing the spent carbon as a slurry,
(2) dewatering the slurry, (3) feeding the carbon into a special furnace where
the regeneration occurs, (4) water quenching the carbon, and (5) returning it
to use. From 5 to 10 per cent of the carbon is lost during this process. The
choice among the alternatives of ¦ on-site regeneration,' purchase of new
activated carbon, or shipment of spent carbon to a regeneration center will be
governed by economic considerations.
Furnaces for carbon regeneration can be purchased for on-site use, but the
smallest of these has capacity for regenerating 1,360 kg/day (3,000 lb/day) or
the carbon requirements at plants having flows of between 38,000 to
76,000 m /day (10 to 20 mgd). Therefore, on-site regeneration is not
economical for small water facilities. Often located near activated carbon
production facilities, regeneration facilities may be too far removed for
economical use by a small water treatment plant. If an existing regeneration
center cannot be used, construction of a regional facility for activated carbon
regeneration should be considered for use by a number of small communities.
If drinking water regulations for halogenated organics are established and
granular activated carbon is used extensively for precursor or haloform removal,
the demand for regeneration facilities will increase.
An alternative to construction, operation and maintenance of an activated'
carbon filter is use of an "adsorption service". The service consists of a
complete modular system furnished to the municipality for a monthly service
fee. Delivery of new carbon and removal of exhausted carbon is then the
responsibility of the leasing company.
c. Applicability and Recommendations. Activated alumina is recom-
mended for removal of arsenic and/or excessive fluoride. Activated carbon can
be used for a variety of purposes. Powdered activated carbon is normally used
only for taste and odor control or for treatment of color. An economic analysis
should be used to determine the applicability of granular activated carbon for
removal of foaming agents, mercury, and organic pesticides. Granular activated
carbon is usually not economical for treatment of color or tastes and odors.

Replacement or regeneration of spent carbon is	of concern when using
granular activated carbon. Alternatives available to	small water treatment
facilities are purchase of new carbon, regeneration	of spent carbon at a
regeneration center, or use of an adsorption service.
4. Clarification
Coagulation, rapid mixing, flocculation, and sedimentation are the
individual processes which make up clarification. Substances producing color
and turbidity can be removed by the clarification process. Clarification can also
be used in the softening of hard water with lime or lime and soda ash.
Clarification followed by filtration is the most widely used process to
remove substances producing turbidity in water. Raw water supplies, especially
surface water supplies, often contain suspended substances causing unacceptable
levels of turbidity. These include mineral and organic substances and
microscopic organisms ranging in size from 0.001 to one micrometer. Particles
in this size range are often referred to as "colloidal" particles. Larger particles,
such as sand and silt, readily settle out of water during plain sedimentation
(without use of chemical coagulation), but settling of colloidal particles using
plain sedimentation is not practical. An important characteristic of particles
suspended in water is the ratio of particle surface area to mass. For large
particles the ratio is relatively low and mass effects, such as sedimentation
under the influence of gravity, dominate. On the other hand, particles in the
colloidal size range have a relatively large surface area-to-mass ratio and these
particles exhibit characteristics dominated by surface phenomena, such as
electric charge. Plain sedimentation, on a practical scale, will not remove
particles of colloidal dimensions. Coagulation and flocculation processes are
required to remove these small particles in sedimentation basins.
a. Coagulation. The terms "coagulation" and "flocculation" are often
used interchangeably to describe the overall process of conditioning suspended
matter in water so that it can be readily removed by subsequent treatment
processes. The coagulation and flocculation processes, though closely related,
are distinct and separable and are defined as follows: the term "coagulation"
means a reduction in the forces which tend to keep suspended particles apart.
The reduction of these repulsive forces allows small particles to join together to

form larger particles which settle readily. The joining together of the small
particles into larger, settleable and filterable particles is called "flocculation".
Thus, coagulation is the precursor of flocculation.
Colloidal particles in suspension in water have electrical charges at their
surface. These charges are usually negative. The charge at the surface of the
particle causes the particle to attract oppositely charged ions present in the
water. The oppositely-charged ions are bound to the outer surface of the
particle and form a "layer" around the particle. Thus, if most of the suspended
particles in a naturally-occurring water have a layer of positively-charged ions
around them, the particles cannot approach each other because of the repulsion
between the positively-charged layers of each. The electrical strength at the
outer surface of the layer of bound ions is frequently referred to as the "zeta
potential". The magnitude of the zeta potential provides an indication of the
repulsive forces between suspended particles.
Negation of the repulsive forces between particles is generally achieved by
adding salts of trivalent aluminum or iron or a synthetic polyelectrolyte
coagulant to the water containing the particles. The aluminum or iron salts
cause a series of reactions to occur in the water; the net result of which is
reduction of the electrical charges on the particle.
Probably the most frequently used coagulant is aluminum sulfate
[approximate formula; AljCSO^)^" H.SHjO]. averaging about 17 per cent
Al2®3; a*so called "alum" or "filter alum". Other aluminum compounds used
as coagulants are potash alum and sodium aluminate, principally the latter.
Salts of iron, such as ferric sulfate, ferrous sulfate, chlorinated copperas
(chlorinated ferrous sulfate), and ferric chloride are also used as coagulants.
Magnesium hydroxide, produced by lime softening of waters high in
magnesium, is another effective coagulant. Organic polyelectrolyte compounds
have also proven effective as primary coagulants. Certain polyelectrolytes, at
low dosage, have been found to significantly enhance the efficiency of turbidity
removal in presedimentation basins, and a number of treatment plants now
utilize polymers for this purpose.
Determination of type and required quantity of coagulant is usually done
through a series of "jar tests". These tests are performed in a laboratory stirrer
by applying varying dosages of different coagulants to representative raw water

samples. The coagulant is rapidly mixed in the water, and the mixture is then
stirred slowly to allow flocculation to take place. Comparison of turbidity
removal efficiencies for each of the various coagulants and dosages yields an
evaluation of the best coagulant and dosage to be utilized. Inasmuch as mixing
times and the quality of the raw water vary, a large number of jar tests are
usually required to determine the optimal treatment process. ,
The pH of the water to be treated often has a significant effect on
coagulation. Aluminum salts are most effective as coagulants at pH values from
6.0 to 7.8. For iron salts, the range of pH values at which coagulation may
occur is somewhat broader. It is very important that coagulation be carried out
within the optimal range of pH values, and, if the pH is not within this range,
it may be necessary to adjust the pH.
There are very few definitive rules to follow .with respect to coagulation,
but the following are useful approximations:
1.	Organic turbidity particles are usually more difficult to coagulate
than inorganic particles.
2.	The required dosage of coagulant does not increase linearly with an
increase in turbidity. In fact, very high turbidities often coagulate
more easily than low turbidities because of the increased likelihood
of particle collisions.
3.	If the suspended particles in water are of a wide range of sizes, they
are usually much easier to coagulate than if all the particles are of
similar size.
Some ions of dissolved salts exert influences on the coagulation processes.
Anions exert a much greater effect than cations, and of the common anions
found in nature, the sulfate and phosphate ions have the greatest effect on
coagulation. Sulfate ions tend to broaden the pH range in which effective
coagulation takes place.
In some cases, coagulation can be improved by the use of coagulant aids
in addition to the usual aluminum or iron coagulants. The most widely used
coagulant aids are activated silica, bentonite clays, and polyelectrolytes.

A partially neutralized sodium silicate solution is known as "activated
silica".-it is often used as an aid to coagulation because it lowers the required
coagulant dose, increases the rate of coagulation, broadens the pH range of
effective coagulation, and causes the floe particles to be tougher, which may
result in longer filter runs. However, preparation of the sodium silicate solution
is difficult, and unless carefully applied, activated silica may actually hinder
coagulation and shorten filter runs.
In water containing high color and low turbidity, the floe produced by the
addition of the aluminum or iron coagulant is often too light to settle rapidly.
Since clays similar to bentonite have a high specific gravity, the addition of
particles of bentonitic clays causes the floe to have a higher specific gravity,
and it settles more readily. Dosages of bentonitic clays generally range from 10
to 50 mg/1.	,
There are a large number of commercial polyelectrolytes currently
available. Polyelectrolytes are long-chain organic compounds which contain
repeating units of small molecular weight. Each of the units has an electrical
charge associated with it, which gives the long-chain molecule a large number of
similar electrical charges. Polyelectrolytes with negative charges are termed
"anionic", while those with positive charges are termed "cationic". Those
having essentially no charge are called "nonionic". Polyelectrolytes act as
bridging mechanisms between particles in water, and cause small floe particles
to agglomerate into large floe particles, with greatly reduced settling times.
Anionic and nonionic polyelectrolytes are often used as coagulant aids in
conjunction with metal coagulants. Cationic and nonionic polyelectrolytes, used
without metal coagulants, have proved effective in reducing turbidity in the
first stage of treatment of waters of high turbidity. Optimum dosages of
polyelectrolytes, which are usually quite low, must be determined by a series of
jar tests..
b. Rapid Mix, In the water treatment plant, coagulation and
flocculation are usually effected in two separate mechanical operations. The
first operation involves rapid mixing of the coagulant and other chemicals, if
needed, including those for pH adjustment and flocculation aid, in a small rapid
mix chamber. The purpose of rapid mixing is to uniformly distribute the
applied chemicals in the water. The interaction between chemical coagulants

and turbidity particles occurs very quickly, so it is essential that the chemical
coagulant be rapidly mixed into the water to insure that the coagulation
process proceeds uniformly. Generally, rapid mixing is accomplished by creating
turbulence with propellers or impellers. As approximate guidelines, the water
flowing into a rapid mix chamber usually requires from 20 seconds to two
minutes to flow through the chamber, and the mixing units usually need 0.3 to
0.6 W per m^/day (1 to 2 hp per fP/second). In small water treatment
facilities, pumps can also be used for mixing.
A useful parameter in the design of rapid mix facilities is the power input
into the water, as measured by the velocity gradient G. Rapid mixing is best
achieved at G values of 500 sec"^ to 1,000 sec"* and detention times of about
* -	s
two minutes, although shorter detention times are often used effectively.
Longer detention times for these values of G result in negligible mixing
improvement. If high G values (>10,000 sec"*) are maintained for as long as
two minutes, the subsequent floe formation processes are retarded .significantly.
c. Flocculation. As previously defined, flocculation is the joining
together of small particles into larger, settleable, filterable particles. The
primary force of attraction between colloidal particles present in water is the
van derWaals force, which is a cohesive force in existence between all atoms.
If the repulsive forces between particles, as described under a) Coagulation, can
be sufficiently reduced to allow van der Waals forces to predominate, the
particles will stick together and form larger particles which settle out of the
water more readily.
The likelihood of collisions between particles is often enhanced by slow
mechanical mixing or agitation ("flocculation") of the water. As more and
more particles are joined together, they form flocculent masses which will
subsequently settle out of the water. Any particles which are struck by the
flocculent material as it settles to the bottom are ensnared in the flocculent
mass. '
Flocculation, which follows coagulation, is usually accomplished in large
tanks with some type of mechanical mixing. The mixing in these basins is
intended to promote collisions of the coagulated particles. The motion
imparted to the water in the flocculation basins must be much gentler than the
motion in the rapid mix chambers; otherwise, the shear forces in the turbulent

water would break up agglomerated floe particles. Mixing for flocculation is
often accomplished through the motion of a series of paddles rotating either
parallel or perpendicular to the direction of flow through the basin. Baffles
should be provided, between each set of paddles to minimize short circuiting.
Walking beam flocculators and vertical axial flow flocculators are commonly
used, and can be placed in existing basins.
As in the case of rapid mixing, the value of the velocity gradient G is
useful in estimating the effectiveness of mechanical agitation in flocculation
basins. The optimal range in values of G appears to be between 20 sec"' and
70 sec"'. If the velocity gradient is multiplied by the detention time in seconds,
an additional parameter GT is obtained. This nondimensional parameter can be
used to characterize flocculation basins. Conventional values of GT range from
30,000 to 150,000. Detention times resulting in the best flocculation usually
are between 20 and 60 min.
d. Sedimentation. After the coagulation and flocculation processes have
been completed, the water must pass through a relatively large basin at low
velocity, to allow the floe particles to settle out. This settling-out process is
generally called "sedimentation" or "clarification". The particles removed
during this stage of water purification are usually small and not of high
density; consequently, large tanks are needed to achieve the quiescent
conditions necessary for settling. In the preliminary water treatment process of
"plain sedimentation", only the heavier particles, such as grains of sand, are
removed from the water, as contrasted to the amorphous floe removed in the
post-flocculation sedimentation process.
The most common types of sedimentation basins are the rectangular, ,
horizontal flow and the center-feed, radial flow. In all types of basins, the
design objective is to obtain, as nearly as possible, the condition of ideal flow
through the basin. Ideal flow for a rectangular basin requires that all of the
water entering at one end of the basin should flow in parallel paths of equal
velocity to the effluent end of the basin. Ideal flow exists in a circular basin if
the centrally-fed water moves in radial paths of equal velocity to the outlet
channel of the basin. This ideal flow cannot be attained under actual operating
conditions because of imperfect inlet and outlet arrangements, friction,
turbulence, short circuiting, etc.

A minimum of two sedimentation basins is usually preferred. However, for
many small water treatment plants, two basins are not practical. Use of a single
sedimentation basin is recommended only if adequate storage is available to
meet water demands while the basin is out of service. If more than one basin is
provided, flow division between the basins should be accomplished prior to
application of coagulating chemicals. Thus, the plant would have multiple
parallel-operating, coagulation, flocculation and sedimentation units.
Rectangular basins vary in width from 1.5 to about 7.3 m (5 to about
24 ft). An approximate width to length ration of 1:4 is common. Basin depths
generally range from 2.1 to 4.9 m (7 to 16 ft). Under comparable conditions,
deeper basins usually perform better than shallow ones. In general, the basins
should be sized to provide an average detention time of 2 to 6 hours. Special
conditions may dictate deviation from these general criteria; detention periods
in the range of 8 to 12 hours, or more, may be desirable for the treatment of
highly turbid waters. If the space available for sedimentation basins is severely
limited, the construction of multiple-story basins, in which the water flows
horizontally along one level and then passes upward or downward to flow
horizontally along another level, may be warranted.
An important parameter in the sizing of sedimentation basins is the
"overflow rate", which is defined as the flow rate divided by the surface area
of the basin. The overflow rate is usually expressed in terms of m^/m^/day
(gpd/ft^), In theory, if the settling velocity of a particle is greater than the
overflow rate of the basin and ideal flow exists, the particle will settle out of
the water before the water leaves the basin.
Actual-sedimentation basins are designed to reduce currents which produce
short circuiting and hinder settling. These currents may be the result of inlet or
outlet induced turbulence, wind action, density differences, sludge build-up on
bottom, etc. The settling rates of alum floe in a conventional sedimentation
basin generally range from 0.17 to 0.26 mm/sec, equivalent to overflow rates of
14 to 22 m3/m-,/day (360 to 550 gpd/ft^). If the particles to be removed settle
more rapidly than alum floe, the area of the basin should be reduced
proportionately; and conversely, if the particles settle more slowly, the area of
the basin must be increased.

Estimates of suitable overflow rates for sedimentation treatment of water
of a given quality can be obtained from cylinder settling tests conducted in the
laboratory. The test procedure should approximate full-scale treatment and
settling velocity distribution curves showing fraction of turbidity remaining as a
function of settling velocity should be developed for each test series.! 1]
A large number of carefully conducted tests axe required to assess
adequately the influence of variations in raw water quality on coagulation,
flocculation and settling. For example, water temperature has a significant
effect on particle settling rates. If the settling rate of a particle at 30°C (86°F)
is 2.2 mm/sec, it would be 1.4 mm/sec at 10°C (50° F) and 'only about
1.0 mm/sec at 0°C (32°F). The increase in viscosity of the water at lower
temperatures greatly reduces settling rates. Settling fate determinations should
include tests at the lowest water temperature that will be encountered.
Application of laboratory settling data to actual basin design requires the
exercise of considerable judgment. Experience at existing plants treating the
same or similar raw water may provide valuable guidance and should be
carefully reviewed prior to final decisions on treatment methods, size of basins,
Flocculation-sedimentation basins, usually circular in plan, can be used to
combine the functions of flocculation and sedimentation. Flocculation is
.accomplished in a circular center well. Sedimentation occurs in the annular
space between the flocculation section and the perimeter effluent weir.
Suspended solids contact claritiers combine mixing, coagulation, floccula-
tion, sedimentation, and sludge removal in a single unit. This type of clarifier
can be very practical for small systems. Coagulation and flocculation take place
in the presence of floe which has been formed previously and cycled back to
the primary mixing and reaction zone. This process maintains a high
concentration of floe particles and enhances the probability of particle
collisions. Settled sludge is removed from the unit continually. The use of these
units usually results in a reduction in the space required for treatment facilities,
and may result in a cost reduction. Solids contact clarifiers are widely used in
connection with lime-soda softening.
A recent development, the "tube" settler, may be used advantageously at
some installations, particularly if the capacity of existing sedimentation basins

must be increased or if little space is available for the construction of new
sedimentation basins. Tube settlers may increase the capacities of sedimentation
basins by 50 per cent or more. For more detailed information on tube settlers,
refer to section V, Upgrading Existing Facilities.
Water containing the suspended particles is often introduced to the
circular basin through a central influent well. The inlet pipe into the influent
well is placed either beneath the basin or suspended from a bridge between the
influent well and outer wall of the basin. The water is discharged from the
influent well into the circular basin, where it flows radially outward toward
outlet troughs along the perimeter of the basin. As in the case of rectangular
basins, the water inlet must be designed so as to minimize turbulence in the
influent flow. A cylindrical baffle at the center of the basin is the most
common type of influent well in use. The outflow from circular basins is
generally collected in an outflow channel which follows all or most of the
periphery of the basin.
Peripheral-feed, circular tanks are also employed. Water is distributed
around the tank perimeter and flows radially toward effluent collection
facilities located in the center.
1. Inlet Arrangements. Inasmuch as the effectiveness of sedimentation
basins is dependent on the degree of attainment of uniform, quiescent flow, it
is essential that the water entering the basin be distributed to minimize
turbulence or intertial currents. Also, the velocities of the water in the pipeline
or flume carrying water to the sedimentation basin must be about 0.15 to
0.6 m/s (0.5 to 2.0 ft/s). Lower velocities will result in deposition of the floe
and sediment in the pipe or flume; higher velocities may cause breakup of the
flocculated particles.
Where inlet pipelines or flumes are used, the conventional methods of
uniformly distributing the water at the influent end of the basin are through
horizontal or vertical slots in a baffle wall, or through a series of orifices in an
inlet chamber. The efficiency of most sedimentation basins is highly dependent
on the design of the inlet arrangement.
2.. Outlet Arrangements. V-notch weir plates are often used for basin
outlets, and these should be installed with provisions for vertical adjustment to

insure uniform flow along the length of the weir. Weir rates commonly vary
from 140 to about 270 m3/day/m (8 to about 15 gpm/ft), with the higher
values for heavier floe, such as that derived from lime softening. Submerged
orifices are also used for basin outlets. Advantages of this type of outlet over
the V-notch weirs include: (1) climatic effects of wind and ice are reduced and
(2) volume above the orifices is available for storage while filter is backwashed.
The recommended maximum velocity through submerged orifices is 0.6m/s
(2 ft/s). Higher velocities may cause currents which inhibit settling or break up
the flocculated particles.
3. Sludge Removal. The solids which settle to the bottom of the
sedimentation basin are called "sludge". This sludge must be removed from the
bottom of the basin before the depth of the sludge becomes great enough to
interfere with effective sedimentation. If the sludge layer becomes too thick,
the effective volume of the basin is decreased resulting in an increase in the
velocity of the water flowing through the basin. The higher velocity of water in
the basin increases the friction between the sludge layer and the water, with
the result that sludge particles are resuspended and enter the outflow from the
Settled sludge can be removed in either of two ways: (1) by taking the
sedimentation basin out of service periodically for cleaning, usually by flushing,
or (2) by mechanical sludge collectors which consist of slow-moving,
mechanically-driven scrapers. Almost all sedimentation basins are now cleaned
by mechanical devices rather than by taking them out of service. Sludge
scrapers force the sludge into hoppers located at the influent end of the
rectangular sedimentation basins. The sludge is drawn off from the hoppers and
discharged to a point of disposal. These scrapers must move at low velocity so
as to avoid interfering with the settling process. The bottoms of rectangular
sedimentation basins are sloped toward the sludge hoppers to facilitate the
action of the mechanical sludge collectors. The most common slope used is
1:100 (vertical: horizontal),
e. Softening. Water softening is the process of reducing hardness.
Hardness is caused principally by calcium and magnesium ions in water.
Softening of the entire supply is usually justified when total hardness exceeds
300 mg/1 and may prove economically advantageous at hardness levels above
200 mg/1.

Two general types of processes are used for softening. These are the lime-
soda ash process and the cation ion exchange process^often called the zeolite
process. The lime-soda ash process is used principally at water treatment plants
serving a fairly large population. The cation exchange process can be similarly
applied and, in addition, is adaptable to small water treatment facilities.
. Equipment, basins, and filters required for lime softening are generally
similar to the facilities used in conventional coagulation-filtration plants. In
fact, many filtration plants, not originally designed for softening, have been
converted to softening plants by the installation of necessary facilities.
Many lime softening plants, particularly those treating ground water, use
solids contact type basins. These basins provide the functions of mixing, sludge
recirculation, sedimentation and sludge collection in a single unit. Basins of this
type, if properly sized, will provide effective softening and clarification
A disadvantage of any lime softening process is the production of a large
volume of sludge of high water content. Provision for sludge disposal in an
environmentally acceptable manner must be considered in designing a lime
softening plant.
Cation exchange or "zeolite" softening is accomplished by exchanging
calcium and magnesium ions for a cation, usually sodium, which does not
contribute to hardness. Basically, this exchange consists of passage of water
through a bed of granular sodium cation media. The calcium and magnesium in
the water react with the media and are replaced with an equivalent amount of
sodium. This reaction is reversible and the exchanger can be regenerated with a
strong solution of sodium chloride (common salt). Disposal of backwash water,
brine waste and rinse water must be carefully considered.. As water with an
increased sodium content, is produced by cation exchange softening, this
process may not be desirable for individuals on low sodium diets. Softening of
hard water using the ion exchange process is discussed in detail in section IV 8.
f. Applicability and Recommendations. Clarification facilities are
readily adaptable to small water treatment systems. Rapid mix, coagulation,
flocculation and sedimentation are recommended for removal of turbidity and
color. Also, laboratory tests have indicated clarification, followed by filtration,

effective in removing the following contaminants: arsenic, cadmium, chromium,
lead, mercury, selenium, silver, radium, endrin and 2,4,5-TP (Silvex). Also an
aid in reducing the bacteria level, clarification should not be used in place of
disinfection. Before the clarification process is selected for treatment of .any
contaminant other than turbidity or color, operational tests with full-size
equipment should be performed.
For design of rapid mix facilities, a detention time of 20 to 30 seconds
and a velocity gradient, G, of 1,000 is recommended. An alternative to the
conventional rapid mix chamber is the use of pumps for mixing. However, a
disadvantage of using pumps is that the mixing cannot be controlled.
The minimum detention time recommended for a floeeulation basin is 20
to 45 minutes, depending on the material to be flocculated. Vertical axial flow
turbines are appropriate for the majority of small water treatment systems.
Paddle reel flocculators parallel to the flow should be compared to vertical
axial flow turbines for use in all but the smallest treatment plants.
Two settling basins are recommended as a minimum for most treatment
facilities. Very small systems such as those using package plants, however, may
use a single sedimentation basin if storage is provided. Flocculation-
sedimentation basins are appropriate for use in small water treatment plants as
are tube settlers. Settling tubes are most commonly used in package water
treatment plants and in modification of existing facilities.
Cation exchange or "zeolite" softening is well-suited for use in small water
treatment systems. In addition to hardness reduction, cation exchange softening
is also an effective method for radionuclide reduction. Lime softening is not
recommended for small water treatment facilities unless an analysis indicates it
to be economically desirable compared to ion exchange softening. Laboratory
tests have indicated lime softening effective in removing arsenic, barium,
cadmium, chromium, fluoride, lead, mercury, selenium, silver, radioactive
contaminants, copper, iron, manganese, zinc and, to a certain degree, TDS.
5. Filtration
Filtration of water is defined as the separation of colloidal and larger
particles from water by passage through a porous medium, usually sand or

granular coal. As water passes through the medium, the suspended particles in
the water are either left in the interstices between the grains of the medium or
left on the medium itself. Sand filtration will remove particles much smaller
than the void spaces between the sand grains. This phenomenon is probably
due principally to the fact that a bed of sand or other similar granular material
possesses a huge surface area, much of which is in contact with the water and
the particles suspended in it. The particles are attracted to the surface of the
granular medium and are held there by relatively strong surface forces. These
surface forces are apparently large enough to attract and bind particles to the
medium surface even though the particles may bear the same electrical charge
as the filter pains. The suspended particles removed during filtration range in
diameter from about 0.001 to 50 micrometers and larger.
Water filters can be classified in various ways. They may be identified
hydraulically as slow or rapid, depending upon the rate of flow per unit of
surface area. Filters are also classed according to the kind or type of filter
media employed, such as sand, anthracite coal, coal-sand, multilayered, mixed
bed, or diatomaceous earth. They may be described according to the direction
of flow through the bed, that is downflow, upflow, biflow, fine-to-coarse, or
Filters are also commonly distinguished between pressure and gravity (or
free surface) filters.
a.	Gravity Filters. Gravity filters are free surface filters and as their
name would imply, are used for filtering water under gravity flow conditions.
Gravity filters are distinguished from pressure filters and are much more
commonly used for municipal applications. The various media types previously
discussed may be used in gravity or pressure filters. Gravity filters are typically
characterized by downflow operation foEowed by an upflow washing of the
filter media to remove the foreign material collected in the bed.
b.	Pressure Filters. Pressure filters are very similar in filter bed
construction to a typical gravity filter; however, in a pressure filter the entire
filter apparatus, including media layer, gravel bed, and underdrains, is enclosed
in a steel shell. An advantage of a pressure filter is that any pressure in the
water lines leading to the filter is not lost, as in the case of gravity filters, but
can be used for distribution of the water once it has passed through the

pressure filter. About 0.9 to 3 m (3 to 10 ft) of pressure head is lost in friction
through the filter bed, but any pressure in excess of this can be utilized for
water distribution.
A disadvantage of pressure filters is the potential loss of media during
backwash which cannot be observed,
c.	Diatomite Filters. A special type filter which is usually operated
under pressure is the diatomite filter. It consists of a layer of diatomaceous
earth supported by a septum or filter element. This layer of diatomaceous earth
is about 3.2 mm (1/8 in) thick at the beginning of filtration and must be
maintained during filtration by a constant body feed of diatomite filter
medium to the influent unfiltered water. At the conclusion of a filter run, the
layer of diatomaceous earth will have increased in thickness to about 13 mm
<2 •j
'(1/2 inch). Filtration rates generally vary from 30 to 120 rrr/mz/day (0.5 to
2.0gpm/ft). The chief difficulty in using diatomite filters is in maintaining the
diatomaceous earth film of uniform permeability and filtering capability.
Applicable methods for disposal of diatomaceous earth filter sludge include use
of a lagoon or landfill.
d.	Media.
1. Single Media. Single media filters are those which employ only one
type of filtering medium as opposed to dual and mixed media filters. Types of
single media filters include rapid sand, slow sand, and anthracite. The vast
majority of present-day water plants use single media filters with the most
common type being rapid sand filters.
Rapid Sand Filters, Rapid sand filters are those filters which commonly
operate at rates. of about 120 to 240 m^/m^/day (2 to 4 gpm/ft^). A
"standard" rate for rapid sand filtration of surface waters is 120 m^/irr/day
(2 gpm/ft ) while ground waters are usually filtered at 180 to 240 m /m /day
(3 to 4 gpm/ft ). If higher rates are to be used in design, great care must be
taken to insure that all pre filtration treatment processes including coagulation,
flocculation and sedimentation will perform satisfactorily and consistently. High
rate filter operation requires excellence in prefiltration treatment.
The filter medium, which has traditionally been silica sand, is generally
supported on a gravel bed. Beneath the gravel bed lies an underdrain system
which collects the filtered water. The filter sand layer is generally about 64 to

76 cm (25 to 30 in) thick and the supporting gravel bed is usually 30 to 46 cm
(12 to 18 in) thick. Head loss through a clean filter is about 0.3 m (1 ft) and
the filter is cleaned by backwashing when the head loss reaches about 2.4 m
(8 ft).
The filter sand usually has an effective size of 0.35 to 0.50 mm and a
uniformity coefficient of 1.3 to 1.7. The "effective size" of a sample of sand is
a grain diameter such that 10 per cent by weight of the sample has smaller
diameters. The "uniformity coefficient" is the ratio of the grain diameter with
60 per cent of the sample smaller to the grain diameter with 10 per cent of the
sample smaller. A sand to be used as a filter medium is tested by sieve analysis
to determine the gradation of grain sizes in the sand. Sand finer than about
0.3 mm stratifies at, or near, the surface of the filter, thereby shortening the
filter runs. Sand coarser than 1.2 mm is generally too large to effect good
removal of suspended matter. Filter sand should be clean and have a specific
gravity of not less than 2.5. For filtration of low pH water, the sand should
not lose more than 5 per cent by weight when placed in hydrochloric acid.
Filter sands for use in water softening plants are somewhat coarser than those
indicated above. For detailed specifications for filtering material, reference
should be made to "A WW A Standard for Filtering Material", AWWAB100-72,
as published by the American Water Works Association.
The gravel bed beneath the filter sand is designed to keep the sand from
passing into the underdrains and also to distribute the wash water uniformly
during backwashing. Ideally, the gravel bed should be composed of well
rounded gravel, with a uniform variation in diameter from the top of the bed
to the bottom, ranging from about 1.6 mm (1/16 in) at the top to about
25 mm (1 in) at the bottom. It is important for the gravel to have few
irregularly shaped (thin, flat, jagged) stones and to be essentially free of soil,
sand, or organic residue of any kind.
The filter underdrains are placed at the bottom of the gravel bed and serve
a dual purpose: (1) to collect the filtered water, and (2) to distribute
backwash water uniformly beneath the filter sand and gravel bed. Types of
underdrains include perforated pipe-grids and false bottom systems of various
types. Perforated pipe-grid underdrain systems have been used; however, the
false bottom systems are preferred.
IV-2 6

Porous plate or porous block false bottoms are suitable where deposition
within the pores of the plates or blocks is not a problem. If deposition occurs,
the plates or blocks must be cleaned promptly as otherwise there will be a
progressive, undesirable increase in head loss across the plates. Structural failure
may occur during backwashing if clogging is severe. Some false bottom systems
employ vitrified clay blocks containing orifices; others are constructed of
concrete and contain orifices terminating in inverted square pyramids filled
with large and small earthenware spheres. A variety of underdrains of the
false-bottom type have been developed and used successfully.
Slow¦ Sand Filters. Slow sand filters have a similar configuration to rapid'
sand filters with a bed of sand supported by a layer of gravel. The filtration
rate for slow sand filters ranges from 2.9 to 5.9 m jm /day (0.05 to

deep. Some mixing of coal and sand at their interface is desirable to avoid
excessive accumulation of floe at this point. This intermixing also reduces the
void size in the lower coal layer causing it to remove floe which otherwise
might pass through. The coarse to fine media arrangement has an advantage
over a single media filter because the effective depth of the filter bed is
increased as is the length of filter runs.
In a conventional rapid sand filter with a single sand layer that has been
hydraulically classified by backwashing. the smallest sand grains will be near the
top of the bed. Any suspended matter that passes through the top few inches
of sand may pass through the entire filter bed. Thus, the effective depth of a
traditional rapid sand filter is only a few inches. However, when a coarse
medium is placed over a fine medium the filtration ability of the unit is
increased, since the larger particles in the water will be removed in the coarse
medium and the smaller particles will be removed in the fine medium. Flow
rates for dual media filters* can thus be increased to about 240 fri^/m2/day
(4 gpm/ft2).	.	..
3, Mixed Media. Mixed media filters are those filters employing more
than" two types of filtering media arranged in a coarse to fine configuration.
Typically, the mixed media: bed consists of three layers: coal with specific
gravity of 1.4 on top, sand with specific gravity of 2.65 in the middle, and
garnet with specific gravity of 4.2 on the bottom. They are normally used in
the proportions of about 60% coal, 30% sand, and 10% garnet by volume.
After backwashing, the three materials become mixed thoroughly'throughout
the depth of the bed. The top of the bed is predominantly coal, the middle is
predominantly sand, and the bottom is mostly garnet, but all three are present
at all depths. In a properly designed mixed media bed, the pore space and the
average grain size decrease uniformly from top to bottom. Just as in single and
dual media filters, the bed is underlain by a layer of supporting gravel.
The vast surface area of the filtering media greatly increases the length of
filter runs. The total surface area of the grains in a mixed media bed is much
greater than for a sand or dual media bed, which makes it much more resistant
to breakthrough and more tolerant to surges in flow rates. One of the primary
benefits of the mixed media bed is an improved finished water quality.

e, Backwashing Facilities. Filter backwashing involves washing the filter
media to remove the material that has been filtered from the water. This
material consists of particles trapped in pore spaces as well as on the surface of
the filter media. Backwash water is applied to the underside of the filter bed
through the underdraws, which should be designed' to provide an even
application of wash water to the filter. The wash water containing the material
removed from the filter medium is carried away in wash water troughs, located
above the surface of the filter medium, Backwashing is necessary whenever the
head loss through the filter exceeds the acceptable value, usually about 2.4 m
(8 ft), or when effluent turbidities are unacceptably high.
The water used for washing the filters should be obtained from protected
storage and can be gravity or pumped flow. As a minimum, sufficient wash
water should be available to allow backwashing of any filter, at , up to
3 9	'J
1200 m /m /day (20 gpm/ftz> for. 10' minutes. Installation , of standby
backwash pumps should be considered to insure reliability. The need for
backwash pumps can be eliminated by construction of an adequately sized
wash water tank at an elevation sufficient to provide the required flow. The
choice between elevated storage tanks and the use of backwash pumps must be
made on a case-to-case basis. Wash water tanks are .usually filled' by small
pumps automatically controlled by the water the wash water tank. The
amount of wash water required will generally average about one per cent of the
water filtered and should not exceed five per cent.	- • : s
In addition to the backwash facilities, some filters are also installed with
surface wash facilities. Filter agitation would better describe its function as the
surface wash aids in cleaning much more than the filter surface.	.
The backwash process does not always wash away all waste material and
mud balls can form from the agglomerated waste within the "filter and on the
surface of the Filter media. These mud balls can eventually become large
enough to clog portions of the filter. An adequate surface wash will prevent
mud ball formation because it aids in agitation of the entire filter bed during
the backwash process,	.
Rotary washers are the most common type of surface wash equipment;
however, fixed jets are also used. The surface wash system usually consists "of
horizontal pipes containing a series of nozzles. The horizontal pipes are

connected by vertical pipes to water lines above the filters. The nozzles have
small orifices through which water is forced down onto the filter surface.
Surface washers are usually started in advance of the normal backwash flow and
are turned off just before the end of the backwash period. Surface wash
systems are commonly used with all types of filters,but are especially necessary
for dual and mixed media filters to obtain adequate cleaning deep within the
f.	Filtration Aids, In order to improve the filtrability of the water and
to permit' higher filtration rates, it is often advantageous to add a
polyelectrolyte to the settled water prior to " its passage through the filter:
Polyelectrolytes, also known as polymers, are high molecular. weight, water
soluble compounds which can be used as primary coagulants, settling aids, or
filtration aids. A filtration aid will increase the strength of the chemical floe
and aid in controlling the depth of penetration of floe into the filter.' It. is
usually added directly to the filter influent and the dosage required is normally,
less than 0.1 mg/1.
The use of a filtration aid is usually warranted only for coarse-to-fine
filters which includes dual media and mixed media filters. Conventional
fine-to-coarse rapid sand filters are" rapidly sealed off at the surface when
filtration aids are used.	&
g.	Applicability and Recommendations, As discussed in section IV4;-
Clarification, filtration after clarification is used in the removal of numerous
contaminants. Rapid sand filters are an acceptable means of water filtration for
most requirements and are quite commonly used today. Dual and mixed media
filters are not as widely used, but are capable of producing an effluent of
higher quality.
Dual-media filters, usually of the coal-sand variety, can be operated at
higher rates-than rapid sand filters with an increase in length of filter runs.
Mixed media filters are an improvement over dual media filters allowing for
operation at even higher rates with longer filter runs. The variations in filter
media only slightly affect the cost of the total filter. A surface wash system
should also be installed in the mixed media filter to aid in backwashing.

Activated carbon filters are to be considered as a method of removing
taste and odor causing organics from water. As discussed in section IV A 3b,
they may be used in place of, or in addition to,conventional filters. The use of
separate activated carbon beds will be more expensive, but is preferred.
In general, gravity .filters are more commonly used than pressure filters in
municipal applications although either is an acceptable means of filtration. The
major disadvantages of pressure filters are that they are completely enclosed
within a steel shell. Thus, access to the filter bed for normal observation and
maintenance is restricted. The steel shells also -require careful periodic
maintenance to prevent internal and external corrosion. However,' for small
systems, the use of pressure filters as opposed to gravity filters is often
advantageous. Initial investment cost savings may'be realized and if the pressure
requirements and conditions in a particular system are such that finished water
pumping can be reduced or eliminated through the use of pressure filters,
additional cost savings may be realized,
6. Disinfection
As; currently practiced in the water treatment industry, disinfection
involves destruction or deactivation of objectionable organisms. These organisms
may be objectionable from the standpoint of either health or aesthetics. They
consist of certain classes of bacteria, viruses, protozoa, and some larger
organisms. Inasmuch as the health of water consumers is of major concern to
those responsible for supplying water, design, of facilities for disinfection must
necessarily be carefully executed.. .	•
Chlorination, including the use of chlorine dioxide, and ozonation are the
most frequently used methods of disinfection for potable water treatment.
Other means of disinfection have been attempted with varying degrees of.
success,. These include treatment with reverse osmosis, ultra-violet light, heating
of water, addition of elements similar to chlorine such as bromine or iodine,
and addition of metal ions such as silver.' None has achieved significant
acceptance by the water supply industry.	¦ *	*

a. Chlorine. The application of various forms of chlorine to water in
order to effect disinfection has come into such common acceptance that
"chlorination" and "disinfection" are almost considered synonymous. Other
modes of disinfection generally lack the persistence of chlorine or are more
costly to use than chlorine.
Terms frequently used in connection with chlorination practice are defined
as follows;
Chlorine Demand, The difference between the concentration of chlorine
added to the water and the concentration of chlorine remaining at the end
of a specified contact period is defined as chlorine demand, Chlorine
demand varies with the water quality, concentration of chlorine applied,
time of contact, and temperature.
Chlorine Residual, The total concentration of chlorine remaining in the
water at the end of a specified contact period is defined as chlorine
residual. Two types of residuals are encountered in chlorination practice.
They are designated: "combined available residual chlorine" and "free
available residual chlorine". They are frequently referred to simply as
"combined residual" and "free residual".
Chlorine is applied to water in one of three forms: as elemental chlorine,
as hypochlorite salts or as chlorine dioxide. The use of hypochlorites and
chlorine dioxide as disinfectants is discussed in subsequent sections.
Elemental chlorine added to water forms hypochlorous acid (HOC1) and
hydrochloric acid (HC1) according to the following reaction:
ci2 + h2o=,hoci + h+ + ci-	(6-1)
This equation is usually displaced to the right and very little Cl2 remains in
solution. Immediately after the above reaction takes place, the hypochlorous
acid (HOC1) dissociates into hydrogen and hypochlorite ions, as indicated in
this equation:
HOC1 - H+ + OC1"	(6-2)

The degree of ionization is dependent on the pH of the water. At a pH of 6.5,
approximately 90 per cent of the hypochlorous acid is not dissociated. If the pH
is raised to 8,5, about 90 per cent of the hypochlorous acid will have
dissociated to hydrogen and hypochlorite ions, as indicated in equation 6-2.
Between pH 6.5 and 8,5, any chlorine present in the water exists as both
hypochlorous acid and hypochlorite ions. Chlorine existing in water in these
two forms is defined as "free available chlorine".
As shown in equations 6-1 and 6-2, the addition of elemental chlorine to
water results in an increase in the number of hydrogen ions (H+) in solution:
This means that the pH of the water is decreased, and treatment for pH
correction may be required if high concentrations of chlorine are applied.
1."	Reactions of Chlorine With Ammonia. If chlorine is added to water
containing ammonia, the ammonia and the hypochlorous acid react to form
compounds known as chloramines. Chlorine will also react with compounds
containing both carbon and nitrogen to form organic chloramines. The relative
amounts of the different chloramines formed are dependent on pH, time,
temperature and the quantities of chlorine and ammonia initially present in the
water. Formation of chloramines greatly reduces the reactivity of the chlorine
and hence longer detention time is required to achieve the same disinfection.
Any chlorine in water which has combined with nitrogen, whether
ammonia nitrogen or organic nitrogen, is known as "combined available
chlorine." It is emphasized that the disinfecting power of combined available
chlorine is of a low order compared with free available chlorine.
2.	Reactions of Chlorine with Other Substances. In addition to the
reactions with water and nitrogenous substances, chlorine also enters into
reactions with other materials present in water. Inasmuch as the oxidizing
power of free available chlorine is high, typical inorganic reducing agents such
as hydrogen sulfide, ferrous iron, and divalent manganese are rapidly oxidized
in the presence of chlorine. Chlorine also oxidizes nitrites to nitrates. Organic
materials present in the water will also react with chlorine. The reactions
between chlorine and organic. substances may involve oxidation, substitution
and addition. A multiplicity of chloro-organic compounds is possible. Some,
such as chlorophenol, have been identified and are known to cause

objectionable tastes when present in trace amounts. The extent and nature of
chlorine's many possible reactions with dissolved organics are not well
defined; but it is known that trihalomethanes are widespread in chlorinated
drinking waters and they result from chlorination. In general, total
trihalomethane concentrations are related to the organic content of the water
and chlorine dosage. At present, a maximum contaminant level for
trihalomethanes has not been established by EPA. However, if a source of low
organic content is not available, special treatment processes that will reduce the
organic concentration prior to chlorination should be investigated. Chlorine
should be applied only after processes which will reduce the organic
concentration and thus decrease the chance of trihalomethane formation.
3.	Disinfection Properties of Various Forms of Chlorine, The means by
which chlorine destroys various types of organisms are not known precisely. It
is suspected that the chlorine penetrates cells of microorganisms and disrupts
vital enzyme activities. Various studies have shown that, of the various forms of
chlorine, hypochlorous acid (HOC1) is by far the most powerful disinfectant
The hypochlorite ion (OCT) is far less effective. Also, the disinfecting power of
combined available chlorine -(chloramine) is much less than that of free
available chlorine. In general, about 25 to 100 times as much combined
available chlorine as free available chlorine is required to achieve equal degrees
of disinfection in the same time period. The fact that combined chlorine
persists for a long time in water is often viewed as advantageous from a water
safety standpoint. This persistence is an indication of low reactivity of
chloramine, a distinct disadvantage insofar as the disinfection rate is concerned.
However, chloramine residuals can be used to provide long-lasting residual in
potable water distribution systems.
4.	Chlorine Dosages. Chlorination is used to eliminate or inactivate
most water-borne pathogens. Those pathogens that are regarded as the most
significant in water are bacteria, amoebic cysts, and viruses. The efficacy of
chlorination in achieving the desired destruction or deactivation of these three
types of pathogens is strongly dependent on four factors: contact time, pH,
temperature, and the type of chlorination used; i.e., free residual chlorination
or combined residual chlorination. As previously indicated, free residual
chlorination is far more effective than combined residual chlorination. Chlorine
disinfection processes are enhanced by low pH, high temperature, and long
contact time.

The effectiveness of bacterial disinfection can be checked by bacterio-
logical tests for the presence of organisms of the eoliform group. Pathogens,
such as typhoid bacteria (Salmonella typhosa) are known to be at least as
vulnerable to chlorine as eoliform bacteria. Therefore, coliforms, which are
easily detected by bacteriological methods, serve as indicator organisms for
water safety. On the other hand, eoliform tests may not be indicative of
parasitic protozoa, such as Entamoeba Hystolytica, the causative agent of
amoebic dysentery. The cysts of this organism are far more resistant to chlorine
than eoliform bacteria and chlorination alone cannot be assumed to provide an
ample margin of safety unless relatively high concentrations of free available
chlorine are employed. Free chlorine residuals required to destroy amoebic
cysts (cysticidal residuals) are higher than those usually employed by water
utilities. However, other treatment processes (coagulation, floceulation,
sedimentation, filtration) are effective in removing amoebic cysts and should
always be employed in conjunction with chlorination when treating surface
waters derived from uncontrolled, watersheds.
Disease-producing viruses must be assumed to be present in waters that are
subject to sewage pollution. In general, viruses are more resistant to chlorine
than eoliform organisms and other enteric bacteria. Therefore, negative eoliform
results may not be indicative of virus destruction. The matter of virus removal
or inactivation by water treatment systems needs, and is now receiving,
intensive study. Currently, it is known that, of all the forms of aqueous
chlorine, only un-ionized hypochlorous acid (HOC1) is an effective agent for
virus destruction. A hypochlorous acid concentration of 1.0 mg/1 will
provide viral inactivation within 30 minutes. Therefore, free residual chlorina-
tion at pH values somewhat below about 7.5 is indicated for effective virus
disinfection. At pH values of 7.5, or lower, about 50 per cent or more of the
free available chlorine will be present as hypochlorous acid (HOCi). As in the
case of amoebic cysts, other treatment processes, such as coagulation and
filtration, assist in virus removal.
5, Application of Chlorine, Chlorine may be applied to water in a
variety of locations in the water treatment plant, storage facilities, or
distribution system and in any of several different chemical forms, as discussed
previously. Chlorine should be applied at a point which will generally provide a
contact time of 15 to 30 minutes. A key feature of chlorine application is

thorough mixing. It is absolutely essential that the chlorine applied to the
water be quickly and thoroughly mixed with the water undergoing treatment.
If required, special chlorine mixing facilities should be provided. In some
systems using raw waters of exceptional bacteriological purity, chlorination is
the only treatment the water receives (all public water supplies should receive
disinfection as a minimum treatment). This is the case with many ground,water
supplies, as chlorine is often added to the pipeline just beyond the
well pumps. In conventional water treatment plants, chlorine may be applied
prior to any other treatment process (prechlorination), following one or more
of the unit treatment processes (postchlorination), or in the more distant points
of the distribution system (rechlorination). Prechlorination is often used
because the water contains a chlorine residual for the entire treatment period,
thus lengthening the contact time. The coagulation, flocculation, and filtration
processes are often improved by prechlorination of the water, and nuisance
algae growths in settling basins are reduced. However, prechlorination is not
universally recommended. Chlorine should be applied after processes which will
remove haloform precursors, such as coagulation and sedimentation or granular
activated carbon adsorption. Haloform precursors are much easier to remove
from water than haloforms.	.
6.	Chlorination Equipment. Elemental chlorine can be injected into
water with either of two types of chlorine feeders: the direct-feed type and
solution-feed type. Solution feeders are preferable to direct-feed devices because
of increased safety, and ease of control of chlorine feed rates, Chldiination
systems can be controlled either manually or automatically. For small water
treatment facilities, manual control is usually adequate. If automatic controls
are used, provision for manual control during emergency situations should be
included. •
7.	Precautions in the Use of Chlorine. The presence of chlorine gas in
the atmosphere of a water treatment plant can pose immediate and serious
health hazards. Adequate ventilation of areas where chlorine gas is to be stored
or handled is a prime safety precaution. Safety equipment such as gas masks or
chlorine detectors must be provided. Chlorine storage and feed facilities should
have outside access only. Safety recommendations are given in the American
Water Works Association's publication "Safety Practice for Water Utilities".

Valuable data on the properties of chlorine and its safe handling are also
available from the Chlorine-Institute.
b. Hypochlorites. Hypochlorites are classified as either dry or liquid
according to commercial availability. Calcium hypochlorite is the predominant
dry bleach in use today; sodium hypochlorite is the only liquid hypochlorite
disinfectant in general use.
Commercial high-test calcium hypochlorite products (HTH) contain at
least 70 per cent available chlorine. Calcium hypochlorite is an off-white
material and is available in granular or tablet forms. Although a highly active
oxidizer, calcium hypochlorite is relatively stable throughout its production,
distribution and storage. Under normal storage conditions, about 3 to 5 per
cent of the available chlorine content is lost in a year. Calcium hypochlorite
should be kept in shipping containers and stored in clean, dry, cool areas.
Containers should be arranged so that they can be easily moved in event of
Readily soluble in water, tablet forms of calcium hypochlorite dissolve
more slowly than granular materials and provide a steady source of available
chlorine over an L8 to 24 hour period. Calcium hypochlorite may be applied
either in dry or solution form.	'
Commercial sodium hypochlorite is manufacturered by numerous
companies and is often referred to as liquid bleach. It usually, contains 5 to
15 per cent available chlorine and is available only in liquid form. Sodium
hypochlorite solutions deteriorate more rapidly than calcium hypochlorite.
Storage should be in a cool dark place and a maximum, shelf life of 60 to 90
days is recommended by most manufacturers.
Sodium hypochlorite is less expensive than calcium hypochlorite. This
lower chemical purchase cost may be offset by increased storage and handling
problems. An alternative to purchase of sodium hypochlorite is use of a system
for on-site generation of this disinfectant. Raw materials required are salt,
either in a brine solution or seawater, power and water. Both the salt and water
must be as hardness free as possible to prevent precipitates from fouling the
system. If sodium hypochlorite is to be used for disinfection, an economic
analysis should be used to determine whether it should be purchased or
generated on-site.

Any hypochlorite solution used in the disinfection process must be
pumped through an injection system into the water to be chlorinated. This
pumping can be accomplished by a diaphragm pump driven by an electric
c.	Chlorine Dioxide. Chlorine dioxide has disinfection properties
approximately equal to those of chlorine. Unstable enough to require on-site
generation, chlorine dioxide is more expensive than chlorine. At this date, there
is no satisfactory test for residual chlorine dioxide. Rarely applied solely for'
the purpose of disinfection, chlorine dioxide is used principally in connection
with taste and odor control.
d.	Ozone. Ozone is produced by. the passage of dry air or.oxygen,
between two high-voltage electrodes. Electric discharges through the air or
oxygen between the electrodes result in the formation of ozone. For small
sytems, air feed facilities are the most practical. Like chlorine, ozone is a toxic
substance. Ozone molecules contain three atoms of oxygen and are highly
reactive. Ozone cannot be stored as a compressed gas; it must be generated at
the point of use and used as soon as generated. Advantages of ozone include:
1.	Rapid and effective disinfecting action. Ozonation is effective against
amoebic cysts, and bactericidal efficiencies are at least as high as those obtained
with chlorination.
2.	Taste, odor, and color problems are largely reduced or eliminated.
3.	Temperature and pH variations have little effect on the disinfecting
capability .-.of ozone, except that at high water temperatures it becomes more
difficult to dissolve the ozone in water.
Disadvantages of ozonation include: '	:
1.	Large quantities of electric energy are required, about 22 to
26 kWh per kg (10 to 12 kWh per pound) of ozone for air feed systems. Better
efficiency, 4.4 to 8.8 kWh per kg (2 to 4 kWh per pound), is obtained when
oxygen feed systems are employed.	: -¦ .
2.	Unlike chlorine, ozone provides no residual disinfection capability.
Residual ozone reverts rapidly to oxygen.

3.	Ozone production facilities must be designed to meet the maximum
rate of use because ozone cannot be stored.
4.	The equipment required to generate the ozone and inject the large
volume of ozonized air into the water is expensive.
5.	Because of the high energy requirements and complexity of ozonation
systems, the probability of system shutdown is higher than with chlorination
systems; consequently chlorination systems are often installed for standby use.
Ozone is being investigated as an alternative disinfectant to" chlorine
because chlorine is implicated in the formation of haloforms. The use of ozone
avoids the formation of compounds such as chloroform, but the reaction
products of ozone have not been identified. Currently, chlorination is to be
preferred over ozonation as a means of disinfection for most water systems.
Ozonation facilities should not be planned at small water treatment plants
unless unusual conditions, which preclude use of chlorination, are encountered.
e. Applicability and Recommendations. Disinfection is used for Bacteria
reduction. For small water treatment facilities, chlorine, calcium hypochlorite
and sodium hypochlorite are the most applicable chemicals for disinfection
purposes. Choice of a specific disinfectant should be based on an economic
analysis. Chlorine is usually the most economical disinfectant for treatment
facilities with a capacity of 2800 m /day (0.75 mgd) and-larger. In general, the
required chlorine dosage will vary from 1 to 10 mg/1 for contact times of from
15 to 30 minutes. Selection of a specific dosage and contact time should be
based on the treatment objective, i.e., disinfection, taste and odor control, etc.
Chlorine solution feeders are recommended for feeding chlorine gas to water.
Hypochlorite will be the most economical disinfectant for the majority of
small water treatment systems. In general, it will be the disinfectant of choice
for treatment facilities with a capacity less than 2800 rn^/day (0.75 mgd). The
decision to use calcium or sodium hypochlorite should be based on an
economic analysis and on other considerations such as storing, feeding and
handling characteristics, Disinfectant dosages mentioned previously must be
increased if hypochlorites are used. Calcium hypochlorite generally has 70 per
cent available chlorine; sodium hypochlorite usually has 5 to 15 per cent

available chlorine. It is usually preferred to use a solution feeder for calcium
hypochlorite. Sodium hypochlorite must be fed through a solution feeder, as it
is only available in liquid form.
An alternative to purchase of sodium hypochlorite is on-site generation.
An economic analysis should be used to evaluate this method or any method of
supplying a disinfecting chemical.,
Use of ozone for disinfection may be desirable in regard to meeting
haloform limits currently being considered by the USEPA. A cost comparison
should be made between the use of ozone and removal of haloform precursor
7. Stabilization
Water leaving the treatment plant and entering the distribution system
should be stable. Thus, it should neither be scale-forming nor aggressive for the
temperatures experienced in the distribution system. Two ways of stabilizing
water are (1) adjustments to pH and (2) addition of polyphosphates or silicates,
a. Adjustments to pH. Water is considered to be stable when it is at the
point of calcium carbonate saturation equilibrium. At this point., calcium
carbonate is neither dissolved nor deposited. If the pH is raised from this
equilibrium level, water becomes scale-forming, depositing calcium carbonate.
The water becomes aggressive if the pH is lowered.
An index developed by W. F. Langelier called the Langelier Saturation
Index makes it possible to predict the tendency of a given water to deposit or
dissolve calcium carbonate. The Langelier Saturation Index is equal to the
actual pH of the water minus the pH at saturation. A positive value for the
index signifies the water is oversaturated and has the potential to precipitate
calcium carbonate. A negative number indicates the water is potentially
aggressive. It is desirable to maintain the water at, or slightly above, the
Langelier saturation equilibrium point in order to maintain a thin coating of
calcium carbonate on the pipe interior. This coating protects the metal against

Stabilization of water is most often associated with an upward adjustment
of pH to control corrosion. However, there must be sufficient calcium ions
present in solution for calcium carbonate to form. In low hardness waters,
where there is a calcium ion deficiency, lime (CaO) should be added for raising
the pH. It is economical and will serve as a calcium supply as well as bringing
the pH up. Ln hard waters, there will be sufficient calcium ions present in
solution. Thus, sodium hydroxide or soda ash should be added to raise the pH
without adding to the hardness.
b.	Polyphosphate. The addition of polyphosphate can be an effective
method for scale and corrosion control. Maximum temperatures in the
distribution system, retention time, and scaling potential are some of the
factors which have an effect on the performance of the specific polyphosphate
and on the dosage requirement. Generally, a low dosage of polyphosphate, less
than 5 mg/1, can effectively prevent scale even in a severe scaling condition.
When adding polyphosphate for corrosion control, somewhat higher
dosages may be required because it is necessary to form a protective corrosion
inhibiting film throughout the distribution system. Phosphates react with iron
and other minerals in water forming a positive-charged- particle. This particle
migrates to the cathodic area of a corrosion cell and deposits as a thin film
which reduces the corrosion of the metal. After the protective film is
established, dosages can be lowered while maintaining the film. Bimetallic (zinc)
polyphosphate or zinc orthophosphate is usually more effective for corrosion
control than sodium polyphosphate.
c.	Silicates. Other additives which are sometimes used as a treatment
for corrosion control include silicates. Sodium silicate in one of the various
proportions of Na?Q and S1O2 has been successfully used. It is a particularly
popular treatment for waters with very low hardness, alkalinity, and pH less
than 8.4.
8. Ion Exchange
Ion exchange is the reversible interchange of ions between a solid ion
exchange medium and a solution. In water treatment applications, ion exchange

is most often used for water softening, but can also be applied to
demineralization by use of cation and anion resins.
a, Softening by Ion Exchange. The ion exchange process which
removes hardness cations from a water supply is termed softening. Hardness is
caused principally by the cations calcium and magnesium; however, cations
such as barium, aluminum, strontium, and others also contribute to the total
hardness of a water supply.
Ion exchange materials for softening .purposes will most generally have ex-
change sites in the sodium form. Hydrogen form resins are also available, but they
are not normally used for softening of drinking water supplies. Sodium cycle
cation resins exchange sodium ions for the hardness cations, thus producing water
with an increased sodium content and a greatly reduced total hardness. Sodium
cycle resins will not appreciably change the total dissolved solids content.
Polystyrene resins are the most popular ion exchange softening materials
in current use. Other substances which have been used as ion exchange media
for softening purposes include natural greensand, processed greensand, synthetic
silicates, sulfonated coal, and phenolic resins, The term "zeolite" has been
applied to any material used as an ion exchange softening medium, but strictly
speaking, it includes only greensands or synthetic silicates.
Softener equipment resembles vertical pressure filtration vessels and
contains internal piping to accomplish backwash, regenerant distribution and
effluent collection; a resin support such as graded gravel or quartz and the
granulated resin are located in the lower half of the vessel. The vessel should be
lined to minimize corrosion.
•5	1
Capacities of 23 to 64 kg per m (10 to 28 kilograins per ftJ) are generally
achieved dependent on regenerant dosage and temperature. Values of
193 m^/m^/day (1 gpm/ft^) minimum flow and 965 m^/m^/day (5 gpm/ft^)
maximum flow are generally used in determining size of the vessel. Resin bed
depth will vary from 0.8 m to 1.8 m (30 inches to 72 inches) to maximize resin
contact time and minimize pressure loss through the exchanger. Continuous
operation, multiple exchanger vessels, and raw water blending can help
accomplish consistent water quality as well as desired flow rates.

Water supplies, especially surface supplies, often contain materials which
are detrimental to softener operation. Suspended solids must be generally
limited to less than 0.06 mg/1 suspended solids per mg/1 hardness (1.0 mg/1
per gpg) with a maximum acceptable limit of 10 mg/1 total suspended solids.
Hydrogen sulfide and free residual chlorine can be tolerated to 0.5 mg/1 and
1 mg/1 respectively; however, lower residual values are more desirable since
both substances cause resin damage and consequently loss of exchange capacity.
The process for regenerating sodium cycle ion exchange resins generally
involves three steps: (1) backwashing (2) application of a sodium- chloride
solution and (3) rinsing. Since downflow operation is most commonly used in
small ion exchange water softeners, backwashing is required to loosen the
media bed and remove any turbidity particles filtered out of the water during'
softening. Backwashing is performed at rates of 240 to 600 m^/m^/day (4 to
10gpm/ft^), depending on the temperature of the backwash water'and the
density of the medium. Backwash periods usually range from two to five
After the unit has been back washed, a sodium chloride solution is applied
to the medium in order to regenerate its softening capabilities. With a
sufficiently high salt concentration, the calcium and magnesium ions in the
medium are replaced by sodium ions. Sodium cycle resins are regenerated with
brine solutions providing 96 to 224 kg of sodium chloride per m (6 to
14 lb per ft*1) of resin; regeneration brines are usually 10 to 15 per cent
solutions of salt. The strength of the brine solution and the contact time of the
brine with the softening medium have a direct effect on the exchange capacity
of the regenerated medium. Exchange capacity increases with increasing contact
time. Contact times of 20 to 35 minutes are common. Installations in coastal
areas may use seawater for regeneration, if the seawater is first disinfected and
treated for removal of suspended matter. Sea water- contains only about 3 per
cent salt and the exchange capacity of a softener regenerated with seawater, will
be less than when regenerated with a 10 to 15 per cent salt solution.
Control of regeneration can be automatic, semiautomatic, or manual.
Potable water systems should include automatic regeneration control based, on a
measured quantity of water passing through the exchange material with
provisions for manual override and multiple regeneration based on actual water

After regeneration, the excess brine solution must be rinsed from the unit
before softening is resumed. About 2.7 to 12m^ (700 to 3200 gal) of rinse
water is required for each cubic meter (35.3 ft ) of softening material. The
total time needed for backwashing, brining, and rinsing usually varies from.
about 35 to 70 minutes.
Disposal of the waste brine solution from the regeneration cycle is a
problem which requires some attention. Disposal may be accomplished by
evaporation ponds or by discharging into a sanitary sewer system.
b, Demineralization by Ion Exchange. Demineralization is the ion
exchange process which removes the dissolved solids content of a water supply.
Dissolved solids will contain both cations and anions and thus necessitate the
use of two types of ion exchange resins. Demineralization processes have been
devised to handle water with total dissolved solids (TDS) in a range from
500 mg/1 to 2000 mg/1. A method for continuous demineralization utilizing a
moving resin bed is currently being manufactured. Both fixed and moving bed
ion exchange systems are applicable within the same TDS range.
Cation exchange resins for demineralization purposes have exchange sites
in the hydrogen form and are divided into strong acid and weak acid classes.
The anion resins commonly used are divided into strong and weak base classes.
Ion exchange demineralizers can be operated to produce an effluent with a
TDS ranging from less than 10 mg/1 to 200 mg/1. As the proposed MCL for
TDS is 500 mg/1, demineralization costs can be reduced by operation at lower
efficiencies or by blending raw water with treated water having a low TDS.
Dissolved organics, strong ozidizing agents, and suspended solids are
harmful to ion exchange demineralizers. Organics, which may be irreversibly
absorbed in the resin, and chlorine can be removed by carbon adsorption.
Strong oxidizing agents can alter the exchange resin. Suspended solids can
inhibit passage of water through the demineralizer and prevent intimate contact
between the water and exchange resin. Suspended solids can be removed by
filtration. High levels of iron and manganese may resist removal during

Capacities for cation resins of 23 to 46 kg per (10 to 20
kilograins per ft^) of resin are generally achieved dependent on regenerant type
and dosage.
Cation resins are usually regenerated with sulfuric acid: however,
hydrochloric acid may also be used. Hydrogen cycle resins are regenerated with
sulfuric acid solutions providing 48 to 160 kg of concentrated (66° Baume)
sulfuric acid per m^ (3 to 10 lb per ft^) of resin. Hydrochloric acid solutions
are used which provide 32 to 144 kg of 100 per cent hydrochloric acid pernr
(2 to 9 lb per ft^) of resin in the form of a 10 per cent solution. Anion resins
usually are regenerated with sodium hydroxide (caustic soda) solutions
providing 64 to 160kg of caustic perm (4 to 10 lb per ftJ) of resin applied as
a 3 to 5 per cent solution.
Control of regeneration can .be automatic or semi-automatic, or manual.
The demineralizer equipment will be similar in appearance to softener
equipment; however, there will be two vessels per unit. The internal piping will
be basically the same. Flow loadings .will be similar and waters containing high
turbidity, hydrogen sulfide, and chlorine concentrations will be detrimental to
demineralizer resins in the same manner as softener resins.
Disposal of demineralizer waste solutions from the regeneration cycle can
be accomplished by first mixing the waste from the cation (acidic) and anion
(basic) units in a neutralization basin and then adjusting the pH to comply with
discharge regulations. When properly neutralized, demineralizer wastes may be
discharged to a sanitary sewer system, if permitted by local conditions.
e. Applicability and Recommendations. The ion exchange process
should be considered for any small treatment softening application. It is an
excellent process for softening hard water, producing an effluent with a
nominal hardness of zero under normal operating conditions. However, for
municipal uses, it is neither desirable nor economical to soften an entire water
supply to zero hardness. The softening costs can be reduced considerably by
blending the zero hardness water with unsoftened bypass water. Thus a finished'
water with any desired degree of hardness can be obtained. Use of ion exchange
softening is not recommended for persons on sodium-restricted diets.

The use of ion exchange systems for demineralization should be
considered for. treatment of water with less than 2000 mg/1 TDS concentra-
tions. Ion exchange demineralizers are capable of producing relatively pure
water, hence blending of treated and untreated water is often desirable because
of lower operation costs.	;
In addition to hardness and TDS reduction, the ion exchange process
should be considered for removal of the following: arsenic, barium, cadmium,
chromium, fluoride, lead, mercury, nitrate, selenium, silver, color, copper, iron,
manganese, sulfate and zinc. .'	•
Some general advantages of ion exchange include low capital investment
and mechanical simplicity. The major disadvantages are high regenerant
chemical requirements and disposal of chemical wastes from the regeneration.
process. These factors make, ion exchange more suitable for small systems than
for large ones.	•
Disposal of the waste brine solution from the regeneration cycle is, a
problem which requires some attention. For small systems, disposal may be
accomplished by evaporation ponds or by discharge into .a sanitary sewer
system. Regulatory agency requirements in a, particular locality may be. a,
controlling factor in selecting a disposal method.	...
9. Membrane Processes
Brackish waters are widely distributed over the United States and are
found underground as well as in estuaries, rivers,, and .lakes. In some, areas,
brackish water may be the only available water for public supply and
consequently must be treated. Two membrane processes, are commonly used in
desalting applications: electrodialysis and reverse osmosis. Electrodialysis (ED)
uses electric current to transfer salts from feedwater through a.membrane to a
reject stream while reverse osmosis (RO) utilizes hydraulic pressure to force
feedwater. through a membrane to a product .stream. Both, pro cesses use energy
at a rate somewhat dependent upon the amount of salts to be removed.
a. Electrodialysis. Electrodialysis is the. demineralization of water by
the removal . of ions through special membranes under ¦ the influence of a

direct-current electric field. Until the early 1970's all commercial electrodialysis
installations were of the Fixed polarity type having' an anode and a cathode at
opposite ends, A polarity reversal system has since been developed in which
each electrode intermittently change's electrode polarity to prevent membrane
scaling. Newer membrane stack designs may contain more than one electrode
pair, to permit internal staging.	' '
Operation of an ED system involves the application of a direct-current
potential to' the electrodes. Since the minerals in water dissociate into cations*
and anions, the positively-charged electrode, called the .anode, attracts .anions
present in the water, and the negatively-charged electrode, called the cathode,
attracts the cations.
Two'types of special membranes are'utilized in electrodialysis. The first,
can be permeated by cations but not anions. The second can. be permeated by
anions but not cations. These membranes are arranged in a stack, with
cation-permeable membranes alternating with anion-permeable membranes.
Feedwater enters the spaces. between the membranes and the direct-current
electric field' is applied to the stack, causing the ions to migrate toward the
electrodes. This results in a concentration'of ions in alternate spaces between'
membranes, and the water in the other spaces becomes depleted in ions, or
demineralized. Water is then drawn off from between the membranes in "two
separate streams, one containing most of the ions and the other relatively free
of ions.
Electrodialysis units are generaly limited to a maximum of roughly 50 per
cent TDS removal per stack to avoid excessive ion concentrations near the
membranes. This situation, known .as concentration' polarization; can result in
membrane scaling and degradation! Higher TDS removals are obtained by
operating stacks in series. Product water recoveries usually range from 75 to
95 per cent per stack. Most plants employ 2, 3, or 4 stacks in series (although a
single stack or more than four may be used) and are designed for 60 to 90 per
cent water recovery and 60 to 95 per cent TDS removal. TDS removals over
90 per cent are seldom achieved in practice because' power consumption and
the danger of scaling increase with brine concentration. ' '
One manufacturer of electrodialysis units recommends that flow through
an ED installation not be allowed to drop below about two-thirds of the

nominal design flow to prevent uneven internal flow and concentration
polarization. This problem can be avoided by intermittent operation, system
storage to equalize flows, or recycling.
Substances such as suspended solids, dissolved organies, hydrogen sulfide,
iron, manganese, and strong oxidizing agents (chlorine, ozone, and perman-
ganate) are deleterious to electrodialysis membranes. In order to remove these
undesirable constituents, the feedwater for an electrodialysis facility should be
pre treated as recommended by the ED supplier. The efficiency of the
membranes may also be greatly reduced by scaling deposits. Hardness, barium,
strontium, iron, manganese, and pH are important factors contributing to
mem brane • seal ing.
Scale prevention for fixed polarity ED unite usually consists of the
® Acidification of the brine recirculation stream to prevent carbonate
and hydroxide scaling.
•	Limitation of calcium sulfate concentrations in the brine effluent.
•	Reduction of iron to 0.3 mg/1 and manganese to 0.1 mg/1 through
¦ ' pretreatment
¦ • Diversion of a small flow for flushing of electrode compartments to
remove gaseous hydrogen and prevent acidic build-up at the cathode
and remove gaseous chlorine and prevent alkaline build-up at the
.. anode.
. Polarity reversal systems rely upon continuous reversal of compartment
roles to prevent scale formation. Polarity is reversed at roughly 15 minute
intervals so that inadequate time is provided for scale to build up between
membranes, eliminating the need for acid or polyphosphate feed. However,
regular in-place chemical cleaning is essential. Physical disassembly and cleaning
may also be required periodically. Iron and manganese reduction is required
with polarity reversal systems and product water recoveries are lowered by
about 10 per cent by additional flushing requirements. In a large polarity

reversal plant, electrode flushing streams could conceivably be returned to the
feed flow. Membrane life of over five years is possible with proper care and
favorable operating conditions.
The economics of electrodialysis is dependent on a number of factors,
primarily the size of the facility, the characteristics of the feedwater, and the
cost of power.
Process power requirements are roughly 0.8 to 2.6 kWh per m (3 to
lOkWh per, 1000 gal) of product water per 1000 mg/1 reduction-of- total
dissolved .solids concentration. Additional pumping power requirements are-
usually 0.8 to 2.6 kWh per (3 to lOkWh per 1000 gal) of product. Power
inputs are dependent upon plant scale, the fraction of design flow being
treated, and pump and equipment selection."
b. Reverse Osmosis. When two solutions containing different concentra-
tions of minerals are separated by a semipermeable membrane, relatively pure
water will migrate through the membrane from the more dilute solution to the
more concentrated solution. This phenomenon, called osmosis, continues until
the build-up of pressure on the more concentrated solution is sufficient to stop
the flow. If there, were no increase of hydrostatic pressure on the rrfore
concentrated solution, the process would continue until both solutions had
equal concentrations of minerals. The greater the difference in concentration of
solutions separated by a semipermeable membrane, the greater the rate of flow
of. water through the membrane. The amount of pressure which • must be
applied to the more concentrated solution in order to stop this flow is known
as the osmotic pressure. If a pressure in excess of the osmotic pressure is
applied to the more heavily mineralized water, relatively pure water will flow
through the membrane in the opposite direction in a .process called "reverse
More process variations are available in RO than ED. Four RO>
configurations have been developed; hollow fine, fiber, spiral wound, tubular,
and plate and frame. The tubular and plate and frame configurations are
comparatively very bulky and have not found wide acceptance due to space
requirements .and high initial cost. The hollow fine fiber and spiral, wound
configurations are more commonly used.

RO plant layouts generally feature flow schematics to maintain brine flow
rates above a minimum. For example, a plant may have three stages, each
having fewer modules than the previous stage. Above minimum flows are
necessary to. avoid localized build-ups of'ion concentrations near membrane
surfaces (concentration polarization) as in ED. The deleterious effects of this
phenomenon in RO are- higher osmotic pressure requirements, lower salt
rejection, and increased likelihood of scaling and membrane hydrolysis.- To aid
in this respect, manufacturers recommend that feed stream flows not be lower
than three-quarters of the nominal design flow. Uniformity of the feedwater
flow may be maintained in the same manner'as previously-suggested for
RO modules have been developed for application to a wide feedwater TDS
range. As TDS contents increase, however, the hydraulic pressure required to
maintain a constant product flow also rises while salt rejection efficiency
declines. Pressures are held constant in normal operation, but power
requirements increase with TDS for a given output because larger feedwater
quantities must be pumped. Standard RO units (suitable for waters up to about
12,000 mg/1 TDS) which are operated at 28 to 35 kg/cm ^ (400' to 500 psi)
achieve 45 to 90 per cent product water recovery and 70 to 99 per'cent salt
rejection.' Rejections of up to 95 per cent are typically achieved. Sea water
desalting modules operate at about 56 kg,'cm- (800 psi), achieve roughly'20 to
40 per cent recovery, and can exceed 99 per cent salt rejection. Power
requirements for the standard modules generally vary from 0.3 to 3 kWh
per nrr (1 to. 11 kWh per 1000 gal) of product water. Power requirements for
sea water desalting are estimated to be 11 to 27 kWh per m- (40 to lOOkWh
per 1000 gal) of product. RO power needs are virtually entirely attributable to
pumping, -but are dependent on a number of factors including plant scale,
pump selection, and membrane age.
The essential element in the reverse osmosis method of demineralization is
the semipermeable membrane. Several types and configurations of membranes
are currently available, with the most widely used being various forms of
cellulose acetate, diacetate, and triacetate, or polyamide membranes. The
characteristics of these membranes vary and constitute an important design

RO membranes are subject to flux (water production) decline. This is a
normal process primarily attributable to the high pressures of operation causing
membrane compaction and aggravated by scaling, contamination, bacterial
attack, and high temperatures. For plants operating around 28 kg/cm-
(400 psi), flux declines of 10 to 20 per cent are typically encountered in the
first -2000 hours of operation after which time little further decline" occurs.
Even higher declines are experienced in high pressure (sea water) systems. Flux
reduction must be accounted for in initial system design. Poly amide membranes
are thought to be more resistant to flux decline than are cellulose membranes
of,which the triacetate and diacetate forms are more resistant than the-acetate
form. RO membrane life expectancy is approximately 3 years with proper care
and favorable operating conditions. Salt rejection .does not necessarily decline
with flux and can be maintained with careful operation. "
Application of standard RO modules should be considered for waters up
to about 12,000 mg/1 TDS. Sea water RO. units should be considered as an
alternative to distillation at higher salt contents.
Due to lower water viscosities at higher temperatures, production by RO
units increases with temperature. If the temperature becomes too high,
however, compaction and irreversible flux reduction may result. The effects of
temperature and pressure are closely related. At higher temperatures, hydraulic
pressures must be lowered to prevent damage to the membranes. Cellulose
membranes generally have a maximum normal operating temperature of 29°C
(85°F). Poly amide membranes may be routinely subjected to temperatures as
high as 35°C (95°F). Although both membrane types can withstand even higher
temperatures for short periods without ill effects, optimal operating
temperatures are generally lower than the maximum values recommended.
The performance of an RO installation as in the case of ED, is highly
dependent upon a number of. water quality parameters. Suspended solids and
dissolved organics are both harmful to reverse osmosis membranes and . should
be removed by pretreatment as recommended by RO supplier.
The effect of oxidants upon reverse osmosis units varies. The cellulose
membranes which are very susceptible to bacterial attack are somewhat tolerant
of chlorine. A maximum continuous level of 1 mg/1 free chlorine (or the

equivalent oxidizing strength) is recommended. The threat to cellulose
membranes from bacteria is sufficient in nature so that even well waters should
be disinfected. Polyamide membranes are reputed to not be susceptible to
biological attack, but are very sensitive to chlorine. Recommended maximum
continuous exposures are 0.1 mg/1 free chlorine at pH less than 8, and
0.25 mg/1 at pH 8 or higher. While the polyamide membranes are apparently
not subject to biological attack, they may be fouled by biological growths.
Because they are believed to be selectively sensitive to chlorination rather than
oxidation, the use of an alternative disinfectant may be feasible. However, no
information on the effect of ozone on polyamide fibers is available. One
manufacturer of polyamide membranes recommends the use of formaldehyde
on an intermittent basis to control slimes.
Discussed earlier with respect to ED, the scale-related parameters,
hardness, barium, strontium, iron, manganese, and. pH are equally important to
RO operations. Scale prevention measures commonly used include the
•	pH adjustment, to between 5,0 to 6.5 to prevent hydroxide and
carbonate scaling.
•	Iron and manganese reduction by pretreatment to levels recom-
mended by RO equipment manufacturers.
•	Use of a polyphosphate to inhibit calcium sulfate scaling.
' • Limitation of calcium sulfate concentration in brine effluent.
c. Applicability and Recommendations. When confronted with treating
brackish or highly mineralized waters, i.e.. waters with high total dissolved
solids concentrations, membrane processes should be considered.
Both electrodialysis .and reverse osmosis are effective for reducing TDS
concentration and both are . suitable for small applications. Appropriate
.pretreatment is' a major -factor in successful operation of 'both processes.' ;
Electrodialysis and reverse osmosis should also be considered for removing
arsenic, barium, cadmium, chromium, fluoride, lead, mercury, nitrate, selenium,

silver, chloride, copper, iron, manganese, sulfate and zinc. In addition, reverse
osmosis is recommended for reduction of bacteria, radionuclides and.- color.
Advantages of ED as compared to RO include low pressure operation with
no need for high pressure pumps, usefulness over a higher temperature range,
longer membrane life, and a constant rate of production with time.
The primary disadvantage is a proportional increase in power consumption
with increasing salt content which prevents ED from being economically
competitive with RO at TDS levels of roughly 5000 mg/1 and above. Also,
because ED removes only charged particles, nonionics such as bacteria'and
dissolved gases remain in the product water. RO systems on the" other hand,
force product water through the membrane, thus removing' dissolved gases,
bacteria, viruses, and other nonionics as well as ionic species. Standard RO
systems are effective for treating raw waters with TDS concentrations up to
about 12,000 mg/1. Disadvantages of RO include flux reduction with time,
shorter membrane life, and possibly significantly greater pretreatment chemical
Each situation should be individually examined to determine which
process should be used for reduction of TDS levels. The economics of the
situation will be the predominant factor in selecting ED or RO.
10. Fluoridation/Defluoridation
Fluoridation is the process of adding fluorides to drinking water in order
to reduce tooth decay. Where necesary, fluorides are removed from water to
prevent dental fluorosis.
a. Fluoridation. Fluorine is the thirteenth most prevalent element in
the earth's crust and is present as fluoride in all natural waters to some extent.
The concentration of fluoride in natural waters is generally less than what-public
health authorities consider to be optimal. Consequently, health departments
often recommend adjustment of the fluoride level by the addition of small
amounts of fluoride compounds to the water.

1. Health Effects of Fluorides in Water. In the 1920's and 1930's, the
incidence of mottling of teeth (dental fluorosis) was definitively linked to the
ingestion of waters that contained high concentrations of fluoride, generally in
excess of 2 mg/1. It was also observed that persons suffering from dental
fluorosis had very few dental caries, and further studies indicated that,
concentrations of fluoride near 1.0 mg/1 greatly reduced the occurrence of
dental caries in children without producing mottling of the teeth.
¦ Inasmuch as fluoridation effects a marked decrease in the number of
dental caries suffered by children, but high concentrations of fluoride cause'
dental fluorosis, the objective of fluoride adjustment in water treatment is to
add enough fluoride to water to reduce dental caries while not adding enough
to cause dental fluorosis.
Maximum concentrations which can be tolerated without the occurrence
of dental fluorosis are given in Appendix ¦ A of this report. These maximum
concentrations- are dependent on the average daily intake of water by children
in any particular location. The average daily intake of water is related to the
average annual maximum daily air temperature, hence maximum fluoride
concentrations are-related lo this temperature parameter. Higher temperatures
dictate a lower maximum allowable level of fluoride.
" 2, Other Effects of Fluoride in Water. The small amount of fluoride
ion added to drinking water does not cause taste or odor nor does it increase
the corrosive properties of the water or cause encrustation in the distribution
system or household plumbing, The use of hydrofluosilicic acid will reduce the
pH and may contribute to corrosion.
tv,	'	' *
3. "-Forms of Fluoride Used in Water Treatment. The most common
compounds used in water fluoridation are sodium fluoride, fluosilicie acid, and
sodium silicofluoride. The choice of which form is best for a water treatment
plant is dependent. largely on the cost of the compound, the availability, and
the mode of fluoride application selected. Other compounds that have been
used successfully by some water utilities include ammonium silicofluoride and
fluorspar. However, these compounds are not recommended for routine
application. The use of ammonium silicofluoride results in an increase in the
ammonia content of the water, which may be objectionable because of the
adverse effect of ammonia on chlorine disinfection, or may be desirable if

chloramines are wanted. Fluorspar is not recommended for routine use because
it is difficult to dissolve. Hydrofluoric acid presents such extreme safety and
corrosion hazards that it is not considered suitable for general use as a water
fluoridating agent. .	...	"
4. Application of Fluorides. The number. and variety of different
fluoride application devices make it impossible, to describe all of them in this
report. In general, the chemical feeders used can be divided into two
categories;- dry feeders and .solution, feeders. Dry feeders, can be further
divided; intp gravimetric- dry, feeders and volumetric dry, • feeders. The choice
between .gravimetric or volumetric dry feeders must be made on the basis of
feed rates,.accuracy requirements, and overall cost.	.
Solution feeders consist of any of several types of positive-displacement
pumps if pressure feed is. used, or a paddle-wheel or bucket apparatus if gravity
feed is used.. Solution feeders are required for application of fluosilicic acid and
may be- used for feeding solutions of . sodium fluoride, etc. Use of zeolite
softened water is recommended for preparing strong solutions of sodium
fluoride; softening reduces scaling problems. The- type of feeder to be used
should be selected on the. basis of capacity,,accuracy, durability, and*corrosion
resistance.	- .	¦ ... . . ¦ .
.. 5.- Points of Application of Fluorides. -The most-important, factor in
deciding on a point to inject fluoride is that all of the water must pass this
point. If no such common point exists, more than one, application point
should be used.. If .fluoride is added to .only a portion of the water and
subsequently blended, the blending must include positive mixing of. all water
to insure uniform fluoride concentration. Fluoride is commonly injected into
the. water in the filter effluen t conduit. If ground water is used as a source of
water supply,-the fluoride should be injected beyond the well head to insure
adequate mixing and uniform dosage of fluoride and to prevent precipitation of.
fluoride compounds in the well. Multiple well installations often require a
feeder at each well. It is generally" more desirable to apply fluoride to the water
in a water line leading to a storage,tank, rather than away from a storage tank,
because the flow toward the tank usually, does not vary, as widely or as rapidly
as the flow away from the tank.. The adjustment of the fluoride feed rate is
much easier if the flow does not• change rapidly.

The. application of fluoride in a conventional water treatment plant should
be after filtration, if possible. When fluoride is applied during the alum
coagulation process, some fluoride will be lost. Lime softening will also remove
some fluoride, especially if the concentration of magnesium in the raw water is
high. If calcium hypochlorite and fluoride are both to be used, they should be
applied as far apart as possible. If injected in close proximity, they would form
a precipitate of calcium fluoride.
6, Automatic Control of Fluoridation. In many cases it is desirable to
have the rate of feed of fluoride controlled automatically by a meter measuring
the rate of flow of water to be treated. This is acceptable if the flowmeter to
be installed is proven reliable and if the apparatus for feeding fluoride can
operate at various speeds. If automatic control is used, provisions should always
be made for manual control in the event of failure of the automatic control.
Medical evidence indicates that skin contact with excessive amounts of
fluoride can cause extreme discomfort. Every effort should be expended to
insure that personnel handling fluoride wear protective clothing and that
adequate safety precautions be taken.
b. Defluoridation. Although fluoride in moderate amounts is beneficial
in the prevention of dental-caries, excessive concentrations of fluoride cause
permanent mottling of tooth enamel and, in severe instances, pitting of the
enamel and loss of teeth. The Interim Primary Drinking Water Regulations
developed by the Environmental Protection Agency for maximum allowable
concentration of- fluorides are listed .in Appendix A of this report, Fluoride
MCL's.are approximately two times recommended optimum fluoride levels.
¦ Fluoride- can be removed from water by percolating the water through
granular" beds of. activated alumina, bone meal, bone, char or tii-calcium
phosphate. The fluoride is removed by a combination of ion exchange and
adsorption. When "activated alumina beds become saturated with fluoride, they
are regenerated by treatment with a caustic soda, solution. Excess caustic soda
is removed by rinsing and neutralization with an acid. Mixed-bed demineralizers
' can also, be used to reduce the fluoride concentration. A mixed-bed de-
mineralizer will remove other minerals along with the fluoride. Additional
methods of fluoride removal include sorption on precipitates of aluminum or

magnesium hydroxide. Precipitation of substantial concentrations of aluminum
or magnesium is required to effect major reduction in fluoride concentrations.
Saline water conversion methods, such as electrodialysis and reverse
osmosis, have shown promise for achieving reduction of fluoride concentrations.
These methods have been applied to brackish waters and have demonstrated
their ability to remove fluoride, etc.. along with other minerals.
Additional information in regard to defluoridation is included in
section III A of this report, under Inorganic Chemicals.
c. Applicability and Recommendations. Adjusting fluoride concentra-
tions in water supplies to optimum levels should be considered as a method for
reducing tooth decay. Recommended water fluoridation compounds are sodium
fluoride, fluosilicic acid and sodium silicofluoride. Fluoride should be applied
after filtration in a conventional water treatment facility. Recommended,
defluoridation processes for small water treatment systems include reverse
osmosis, electrodialysis, activated alumina, bone char, and, if used for removal
of magnesium, excess lime softening.
Disposal of wastes from defluoridation treatment should be given careful
consideration due to the toxic nature of waste.
Control of a water treatment facility involves more than valve turning and
button pushing to start and stop equipment. In order to determine which valves
to turn "and which equipment to use the operator must be able to determine
how well the plant is functioning. Not only does the operator need to know
whether the MCL's are being met but also needs to know whether the
treatment processes are under control. To determine all of this the operator
will need laboratory analyses of the water and information provided by plant
1. Sampling and Analysis
Treated water must be sampled, for contaminants included in the drinking
water regulations, at the proper locations and at the required frequency.

Analyses must be in accordance with the methods prescribed in the regulations.
Since the inorganics, organic pesticides and radionuclides require extensive
equipment and analytical skill these tests must be conducted by a certified
laboratory. Approximate costs per sample for these analyses done by a
commercial laboratory are as follows:
Most state health department laboratories can also perform these analyses.
The rest of the required analyses including turbidity (surface water or
combination ground and surface water), chlorine residual (as a State allowed
substitute for a portion of the coliform analyses), and coliform analyses would
cost from $4 to S10 per sample in a commercial laboratory. To aohieve proper
results, the chlorine residual should be run almost immediately and the
coliform analyses should be run within 24 hours. Use of a commercial
laboratory for chlorine residual analyses is not feasible. Turbidity analyses are
required daily for surface water plants and the cost in a commercial lab would
be very high. The plant operator in all plants should be able to run the
turbidity and chlorine residuals in a plant laboratory facility. Probably only
those facilities of about 3800 m^/day (1 mgd) and larger will want to run
in-plant coliform analyses. For smaller plants either the county or state health
department could probably run the coliform analyses.
In addition to the required tests, each plant should run the following tests
in-plant as a control on the treatment processes:
Temperature of the water is important because it influences the rate of
chemical- reactions, chlorine effectiveness, and the settleability of floe. The
higher the water temperature the faster the chemical reactions and the better the
settleability. The pH and alkalinity of a water are general control parameters
since a number of the chemicals added to tne water raise or lower the values of
Organ ics
S 90 - $150
$160 - $270
$ 60 - $120

these parameters. Effects of pH and alkalinity have been discussed previously
for contaminant removal and treatment techniques.
Other control tests may be required depending on the contaminant
removed or the treatment processes used. For instance, where aeration is used
in a lime softening plant, carbon dioxide could be a control parameter.
2. Laboratory Facilities
Each water treatment facility should have minimum laboratory, facilities to ,
do the following tests:	.
Chlorine Residual
The laboratory size required for these tests should be about 11 mr .(120 ft^) .
including space for' laboratory record keeping. A laboratory counter .about 2.4 m
(8 feet) long should be provided with storage space for equipment.
The cost-* for- a minimum laboratory facility would be about $7000. This
can be broken down as follows:
$ 650
Additional: facilities • and equipment to do coliform tests would cost about
* Cost based on engineering estimate.

3. Metering, Instrumentation, and Control
Metering at a small water treatment plant can be kept fairly simple.
Generally all that is needed is a meter on the raw water and one on the
finished water leaving the plant. The raw water rtieter can be a propeller type
meter with flow indication only. The finished wkter meter Should be a venturi
flow tube or propeller meter which at least totalizes flow and possibly records
flow.	,	....
Filter instrumentation and control for those supplies which are filtered
should be provided with the :filter package'. The'simplest forifi of control is a
•	flow splitter ahead of the filters with; a water level sensor Bn'each" filter which
operates: the filter rate controller;; Another simple method" of contrtil is to
:bperate "the filters with a variable decliiiing ratei'Hbwever sohie'stkte regiilitbry
agencies may not 'approve' this m'ethod. No- indication of the 'filter backwash
rate is required, if - the' flow has been physically limited to1 not exceed the
maximum desirable rate.' However,: indication of head loss through the filter
should be provided.	:; . ; -	; .
For surface, water, plants where a;• finished water turbidity sample is
; required daily, it may be advantageous to:put a continuous turbidimeter on the
•	filter:effluent. This; turbidimeter will have to. be calibrated and may have' some
maintenance requirements principally related to keeping the -optical, system
clean and aligned. A back up laboratory turbidimeter will still be required for raw
water turbidity and for filtered, water; turbidity when'the: continuous'unit-is out
of semce.	;¦	.*	»* <>. :
A control panel should be provided in each water treatment facility. .The
panel should be part of "the plant motor control center. The control panel
should contain all indicators, totalizers, and. recorders for the instrumentation
. discussed above in addition . to remote indication of, the. status of, all,motor
.operated equipment. Actual on-off controls, for. the motors at the treatment
facilities ,should be local to reduce instrumentation and control and. to require
the operator to, go to the piece of equipment,and observe. it. when . starting ;or
stopping it. Remote on-off controls, can be employed for- wells,: distribution
system pumping and other facilities located ,away from ; the . water treatment

. > Disposal of wastes generated during the various-water treatment .processes
must receive careful consideration. Selection of a disposal method will influence
water treatment,plant location and design, .
1. Sources, Quantities, and Characteristics of Wastes
The wastes generated in a water treatment plant, are composed of .the
natural solids removed from, the raw water, as .well as the chemical precipitates
.resulting from chemical addition. Thei nature .and quantity of the raw. water
, solids will vary from one plant, to .another.. For example, natural; solids removed
.in a surface water plant are idependent upon sediment washed into the, water
supply by rainfall, seasonal algal growths, spring turnover in -lakes, and other
factors. The nature and. quantity of chemical solids are a function of; the
chemicals added and the resulting precipitates.
a.. Sources.! Predominant water treatment plant:wastes are waste solids
in the; sedimentation , basin blowdown: and .the 'filter, backwash water; Other
• wastes include spent brines from regeneration of ion exhange units and spent
granular activated;carbon. : -	:• ... ' . .tr	- ¦¦
!b; Quantities of; Wastes Produced.- Quantities of wastes can best; be
determined not by measuring the waste stream, but through the use of
chemical mass balance and other available data, such as suspended solids
information. i:	r	'!
1. Solids Produced by Turbidity Removal Natural solids are normally
removed in sedimentation' basins with the chemically produced solids. If the
suspended solids concentration'(mg/1) in the raw water is'available, then the
amount of waste solids can be calculated directly. If suspended soli'ds data are
not" available then an attempt should be made to con-elate turbidity and
suspended solids. The solids removed can'be calculated as follows, assuming all
natural solids are removed in the treatment process:

Solids produced (kg/day) = (suspended solids-mg/i) x (0.001) x (flow-m3/day)
Solids produced (lbs/day) = (suspended solids-mg/1) x (8.33) x (flow-mgd)
2. Solids Produced by Chemical Addition. The amount of. waste solids
provided by chemical addition depends on the type of chemical added and the
dose. The following paragraphs describe the chemicals utilized in each process
of water treatment and the amount of solids produced. .. .
Coagulation. A reasonable basis for estimating the * chemical solids
produced, when the coagulant alum is used, is indicated by the following
reactions:	-
AljfSO^j ¦ 14 H2O -+ 2A1^+ + SO^" +. MH2O (ionization)!.
2A13+ + 60H"^2A1_(0H)3	"	¦
Commercial alum contains about 17 per cent AI7O3 or,9 per cent Al+++.
Inerts are negligible. Essentially all aluminum added to the water is removed.
The sulfate (SO4") component of the alum remains in the water and appears as
a residual mineral in the finished water.	,	,
Aluminum hydroxide [Al(OH)g] resulting from alum addition can be
computed from alum use in lbs or kg/day [A 1 c] as follows:
Al(OH)3 = [0.26] IA1 c J (lbs or kg/day)	1 ' "
•" The results of similar calculations made for other coagulants used in water
treatment are shown in Table 25.		
Table 25	-
Solids Produced (dry)
lbs or kg/day
[0.26] [Ale]	: '
[0.46] [Fee] ; =•'- !
[0.40] [Foe] . ¦ =
[1.0] [Pc]
[0.3] [Na2Si03]	" ;
lbs or kg/day
[Ale] Alum
[Fee] Ferric Sulfate
[Foe] Ferrous Sulfate
[Pc] Polymers
[Na2Si03] Activated Silica

Taste and Odor Removal The chemicals generally used to oxidize taste
and odor producing compounds are chlorine" and potassium permanganate.
Activated carbon is also used for taste and odor removal but acts as an adsorbent.
The amounts of waste solids produced by the removal of tastes and odors
are developed in a similar manner as those solids produced by the addition
of coagulants. Table 26 presents the chemicals and resulting solids produced
in removing taste and odors.
- " -	'	Table 26 ¦
Chemicals	1		. Solids Produced (dry)
lbs or kg/day	lbs or kg/day
" ' '	• - i	- i ' ' .
[AC] Activated Carbon	11.0] [AC]
; [KMn04] Potassium Permanganate	[0.55] [KMn04]
[CI] Chlorine	None
: '•Lime-Soda Softening. The lime-soda and ion exchange processes are the
softening processes most commonly used to remove hardness from water.
Stabilization. Stabilization of lime-softened water may be accomplished
by recarbonation, split treatment, or by the use of polyphosphates.
Polyphosphates contribute nothing to solids production and precipitation
induced by recarbonation or split treatment is accounted for by calcium and
magnesium mass balances. These stabilization processes are not sources of
chemical solids.
Disinfection. Disinfection is usually accomplished by chlorine and/or a
combination ' of ammonia and chlorine (chloramine process). All reaction
products'are soluble;'hence; disinfection produces no chemical solids.
Fluoridation. Some plants'practice fluoride adjustment of the'water. Any
fluoride addition becomes part of the dissolved solids and does not contribute
to'the wastes:'' "
c. Characteristics. Water treatment plant waste products'exhibit various
characteiistics, "depending on their source. Knowledge of these characteristics is
basic to the selection of necessary waste disposal methods.
1.'"Waste	Solids from Coagulation with Aluminum Salts. The wastes
produced by coagulation ' with aluminum salts normally have a solids
concentration of 0.5 to 2 per cent when they are removed from a
sedimentation basin. The sludge is usually bulky, and gelatinous in consistency.
It is difficult to dewater and a solids concentration of only 8 to 10 per cent
can .be achieved when it is thickened in a lagoon. Dewatering by mechanical
devices such as the centrifuge has obtained a 15 to 20 per cent solids
concentration. This concentration can only be attained if" the sludge is first
pretreated with a polymer. Without pretreatment, a 5-6 per cent solids
concentration is an upper limit. Vacuum filtration has not "been successful in
dewatering waste solids from water treatment plants.. ,
2.	Waste Solids. Produced from Coagulation, with'Iron Salts. The solids
produced from the coagulation of water by iron salts are similar to those
produced by coagulation with aluminum salts. The consistency and difficulty in
dewatering are similar but the iron floes generally are not as fluffy and
gelatinous as alum.

3. Waste Solids from Softening by Chemical Precipitation. The
characteristics of solids from the precipitation of hardness by lime and soda
varies with the composition of the raw water and the dosages of chemicals used
for softening. Waste solids collected in the settling basins of lime and lime-soda
softening plants have been reported to range from 2 to 33 per cent solids
concentration. Softening waste solids have been dewatered in lagoons to a
solids concentration of 50 per cent. Mechanical devices such as centrifuges
can dewater lime softening waste solids, from 40 to 65 per cent solids. The
greater the ratio of magnesium hydroxide (MgCOH^I to calcium carbonate
(CaCOj) the lower the per cent lime softening waste solids concentration.
4.. Filter Wash Water- , Filter backwash water consists of fine natural and
chemically precipitated solids that are not removed in the sedimentation basin.
The solids concentration is low, averaging 0.08 per cent solids (800 mg/1 total
suspended solids). Filter wash water is usually 2 per cent of the water produced.
Filter wash water by itself cannot be dewatered by mechanical means. When
lagoon ed. the solids are allowed to settle and the supernatant is decanted..
J. Spent Brine Solutions. As discussed previously, the characteristics
and amount of waste brines vary widely. The characteristics of a composite
..sample, of spent brine, discharged, from one large zeolite. plant are given in
Table 27.	, '	'	' -'
		~ J ¦ ¦ Table. 27 . ' ¦.
Constituent	mg/l,.
Sodium and Potassium	3,325
Calcium " '	1,720
Magnesium " -•	600
Chloride	9,600
• Sulfate .	-328
Dissolved Solids	15.654

2. Waste Disposal Practices
Various methods of waste disposal .have been used by the water utility
industry. No specific method of waste disposal is most suitable for all wastes,
as the properties of different types of wastes vary considerably.
a.	Direct Disposal. The predominant method of disposal of backwash
water and waste solids from"water treatment plants has been'direct discharge to
surface waters; This method is now being abandoned due to regulations for
discharges to water courses set by the Environmental "Protection Agency.
Howevef, the EPA is considering direct discharge to the larger rivers such as the
Missouri, Ohio, and Mississippi Rivers. Other than direct discharge, small water
treatment plants have few reasonable methods of disposal available!
b.	Vacuum Filtratibn, Vacuum" filtration equipment is extensively used
for dew ate ring wastewater treatment plant sludges, but its application to water
treatment plant "waste solids is limited. This method utilizes a cylindrical drum
covered with a porous fabric made of metal mesh, steel coils, wool, cotton,
nylon, saran, or one of the new synthetic fiber cloths as filtering media.
Alum waste solids have proven difficult to dewater by vacuum filtration.
The gelatinous nature of the waste solids produced by alum almost precludes
the use of vacuum filtration without precoating the filter with diatomaceous
earth. The cost of precoating is high and the remaining solids-precoat mixture
remains gelatinous in nature and may not be 'suited for ultimate disposal.
Vacuum filtration of lime waste solids Has been more successful but the waste
solids were thickened prior to being vacuum filtered. High costs for equipment,
operation'' and maintenance, and disposal of dewatered waste solids make
vacuum filtration impractical for most small communities.
c.	Centrifugation. Centrifuges are becoming more popular for dewater-
ing water treatment wastes since they are able to handle dilute or thickened
waste solids. Alum and softening wastes can be concentrated in a centrifuge to
the per cent concentrations previously discussed.
High capital, operation, and maintenance costs make centrifugation
beyond the financial means of most small communities. There is also the
consideration of the cost of the ultimate disposal of the dewatered waste solids.

d.	Drying Beds. Sand beds for drying water treatment waste solids are
basically identical to those employed in sewage treatment. An underdrained
sand bed may include decant at ion, but basically water is removed by drainage
and air drying.' A sufficiently shallow waste solids depth to allow cracking of
the solids down to the sand-solids interface will accelerate drying and yield
drier cakes.
Both the drainage and decantate can be discharged to the sanitary sewer
or discharged to a surface water if the discharge, meets permit requirements.
The dried solids can be removed from the drying beds with a front end loader
but must be disposed of, either in a .sanitary landfill or by direct land
application. A comparison between lagoons and , drying beds shows that drying
beds are more dependent on weather for successful, operation, have more
difficulties in removing sludge, have greater land requirements, incur higher
capital costs, and require more operation and maintenance.
e.	Lagoons., The most common treatment method presently utilized at
water treatment plants for handling water, treatment plant wastes is lagooning.
, In areas where ample land is available, which is generally true near small water
treatment plants, lagooning can be quite economical. It takes advantage of
natural temperatures (for evaporation and freezing) to aid in the dewatering of
waste solids. Lagoo'ning is not so much a disposal method as one for
dewatering, thickening, and temporary storage.
.Water is removed by decantation or by evaporation, with some drainage.
Evaporation may provide a hard crust, but the remaining depth can turn into a
viscous liquid upon agitation. In cold climates, freezing aids in dewatering by
separating attached water from the solids. After thawing, the solids are in the
form of small granular particles that settle readily and additional water can be
Solids removal is accomplished by a dragline or clamshell. Dumping the
waste solids on the banks can be used to air dry them further prior to later
When sufficient land is available, filled lagoons can be abandoned,
eliminating an ultimate disposal problem. In communities where this is not

possible, alternatives include sanitary landfill, land application,and reuse of
products from water treatment plant wastes such as the use of calcium
carbonate as a soil stabilizer. Where waste solids remain in place indefinitely
and the land is not reclaimed, unsightly spoiled land areas "result; ' '
Serious consideration should be given to the disposal of the decantate and
underdrainage. Discharge to a surface water is recommended if. the discharge
meets permit requirements. An alternative method is. discharging to the sanitary
sewer. In water scarce areas, recycling through the water treatment plant has
proven to be economical. In small water treatment plants, however^recycling of
the decantate or underdrainage is economically questionable and can present
operating problems. Recycle of the wash water can be a viable alternative- even
though it may not be operationally desirable.
While operating, costs of lagoons are low, factors such as climate
intermittent or continuous input, solids concentration of the waste, the
availability of one or more lagoons, and the method and place of ultimate
disposal will have a bearing on the land area required.. Generally, at least two
lagoons are needed for waste solids and a third lagoon for backwash water. ¦ .
Current lagoon design practice includes the following: r. ,	...
1.	Location free from flooding,
2.	When necessary, dikes, deflecting gutters, or other means of diverting
surface water.	" :"
3.	A minimum depth of 4 to 5 feet.	' '¦
4.	3 to 5 years solids storage volume.	_ .....
5.	Multiple cells.	. .. .. e
6.	Adjustable decanting devices.
7.	Width of lagoon narrow enough to allow removal of waste solids by
dragline, clamshell, scraper, tugger hoist, or any other mechanical
equipment that might be employed.	,

The minimum embankment top width should be 8 feet to permit access of
maintenance vehicles. Lesser top widths can be used for very small installations.
The maximum inner and outer embankment slopes should not be steeper than
3:1, horizontal to vertical, and the minimum inner embankment should not
have a slope less than 4:1, horizontal to vertical. The embankments should be
seeded; Perennial type, low growing, spreading grasses that withstand erosion
and can be kept mowed are most satisfactory' for seeding of embankments. In
general, alfalfa and other-long-rooted crops should not be' used in seeding, since
the roots of-this "type" plant are "apt to impair the "water holding'efficiency of
the dikes. Additional "protection for embankments (riprap) may be necessary
where dikes are subject-to wind action or severe flooding of an adjacent water
course. •:
Problems can exist with insect breeding but can be controlled with
insecticides. Lagoons should be fenced to prevent access by unauthorized
persons.1.--.' ••
f, . Discharge to Sanitary Sewers. An increasingly popular' method' of
disposal of water-treatment plant'-wastes is discharge to the sewage'treatment
facility via sanitary sewers. This particularly true for a -small
community served by sewage lagoons." If the sewage lagoons are of sufficient
size to handle the water treatment wastes, then construction of separate
facilities could not be justified.
Evaluation of the following considerations before the. discharge of water
treatment plant wastes to a municipal wastewater treatment plant is
recommended:	¦.	'	;
1,	Possible damage to sewer system due to clogging.
2.	Amenability of the waste to existing processes, principally in
mechanical treatment plants. -	' :
3., Hydraulic capacity of sewers, pumping .stations, and sewage treatment
4. The effect of waste on the final plant effluent.

5.	A direct connection between the water treatment plant waste disposal
line and the sanitary sewer must be prevented.
6.	Waste solids should be discharged over a 24 hour period, not as-a slug
flow. If this is not possible, some other time period, compatible with
' operation of the wastewater treatment plant,- should, be. used. ...
g.	Spent Brine Solutions. For a small community, .disposal of spent
brine solutions to the sanitary sewer is the most feasible method of treatment.
The spent brine solution should not be discharged as a slug,but discharged
continuously over a 24 hour period. This will avoid any .damage:' to the
wastewater treatment facility. A small holding basin can be used to equalize the
discharge of the spent brine solution.
h.	Summary of Waste Disposal Practices. The current restrictions" on
the discharges to lakes and streams have made water treatment plant designers
look at alternatives to direct disposal. Small communities with: small water
treatment facilities are at a disadvantage since the costs are too high for them
to use mechanical devices to' treat water treatment plant wastes. The
alternatives left to a small community are disposal to a sanitary sewer,
lagooning, and drying beds.
The small community should be made aware of the fact that if their water
treatment plant discharges a waste to a receiving stream or lake, a' discharge
permit called "The National Pollutant Discharge Elimination System-Permit''
(NPDES) 'must be obtained. This permit sets restrictions 'on the - concentration
of parameters, such as suspended solids and pH, that will be discharged to :a
stream or lake. If the water treatment plant does not discharge to a'-waterway,
the permit is not required. This situation would occur if the plant'disposed all
their wastes to the sanitary sewer or they treated waste solids and/or backwash
water with lagoons or drying beds and returned the dec'antate* or drainage to
the water treatment plant or disposed-of it to the sanitary sewer. Therefore, it
is advantageous for the small community to investigate the possibility of-using
their wastewater treatment plant to treat their water treatment plant's "waste.
In many cases, the wastewater treatment facility may -hot be able to
effectively treat wastes due to the increased amount of solids or volume

contributed by the water treatment plant. In this case, the solids must be
treated at the water treatment plant and disposed elsewhere.
For small systems, the most generally used method of dewatering water
treatment plant wastes, except for spent brine solutions, is lagooning. The
drainage and decantate can -be discharged to a surface water or to the sanitary
sewer. The dewatered waste in the lagoons must ultimately be removed and
placed in a sanitary landfill or applied to the land.
Generally, more than one unit process will be utilized in a treatment
facility. A possible exception to this might be disinfection which could be the
. single unit process used for treatment of a well supply. Many process
combinations ' could be used for water treatment. Combinations of unit
processes which comprise conventional treatment facilities or package treatment
plants are presented in the following sections.
1. , Conventional Facilities
-	..., Four common types of treatment plants have been selected as examples.of
conventional unit-process combinations constructed at the plant site. Design
.criteria and schematics for existing plants are presented to indicate how unit
-processes can be designed and combined into a treatment plant. The treatment
plants that will-be discussed include (a) turbidity removal, (b) ion exchange,
. (c), .lime softening, and (d) iron and manganese removal.
t. - -a, Turbidity Removal. The turbidity removal plant at Garnett, Kansas
removes- about I00mg/1 suspended, solids from the raw water taken from
-.Lake Garnett and Cedar Creek. Rapid., mix, flocculation, sedimentation, and
filtration are combined to provide a two stage coagulation/filtration plant for
the removal of turbidity. As shown on Figure 1, alum is used as the coagulant
to remove turbidity and lime is fed to provide alkalinity for reaction with the
-	alum and to control the pH. Chlorine is added prior to filtration for


disinfection of the water. Unit process design data for the Gamett plant is
presented in Table 28.
b.	Ion Exchange. A well water serving as the raw water supply for an
AT&T installation in Grant Park, Illinois, contains 375 mg/1 hardness as CaCOj
and 2 mg/1 of iron. To meet requirements for engine cooling water standards the
hardness must be reduced to 100 mg/1. In addition, to meet U.S. Public Health
Service Drinking Water Standards in effect at the time of plant design, the iron
concentration must be reduced.
In order to remove the hardness by a zeolite softener the insoluble iron
must first be removed to prevent fouling of the1 media in the zeolite softener,
thus rendering it ineffective for removing hardness. Figure 2 shows the
placement of a pressure filter; before, the zeolite softener. This removes
turbidity which is a result of insoluble iron formed in the line from the well.
The water is then softened by the zeolite softener. Sodium phosphate is added
after treatment to stabilize the water and sodium hypochlorite is added to
disinfect the water. The , capacity of the , softener is 16,200 grams
(250,000 grains) of hardness. With the.hardness of water equ^l to 375 mg/1,
the Iters'of water softened between regeneration is
16,200	i
„ = 43,200 liters or 43.2 nr (11,413 gallons)
At a flow rate of 54.5 m^/day (14,400 gpd), two regenerations are needed per
day and the salt tank is refilled every three days. Additional design data are
presented in Table 29.
c.	Lime Softening. The City of Troy, Kansas, has constructed wells
along the Missouri River for raw water supply. The raw water is high in
hardness and alkalinity, and contains iron and manganese.
The treatment process illustrated on Figure 3, consists of aeration, excess
lime softening, two-stage recarbonation with intermediate settling, and
filtration. The induced draft aeration serves a dual purpose, oxidizing iron and
manganese so they Van be removed, and removing carbon dioxide which will
reduce the amount of lime needed for softening. Lime is then added in the
solids contact unit, which mixes the lime into the water and allows settling of





Table 28
Design Flow, m^/day (mgd)	378S	(1)
Primary Flocculation
Number of units 		2	2
Basin dimensions, m (ft)	3.05 x 8.53	(10 x 28)
Sidewater depth (SWD), m (ft)	3.66	(12)
Detention time, hr *	11
Flocculators — hydraulic with baffles
Primary Sedimentation 	
Number of units ,	1	• 1
Basin dimensions, m (ft) , 6.40 x 11.13	(21 x 36.5)
SWD, m (ft)	3.66	. (12)
Detention time, hx 	¦ -'	2	; 2
Overflow rate, nr/m /day (gpd/ft )	5 ' 45.57	; (1120)
Rapid Mix
Number of units _ 			.J	1	= 1
Basin dimensions, m (ft)	'1.22 x 1.22	: (4 x 4)
SWD, m (ft)	••	: 1.83	(6)
Detention time, sec.	62*	62
'Mixer, watt'(hp) 	"	2238	(3)
Mixer G factor, .sec"!		700	700
Secondary Flocculation
Number of units ' " ¦	2	2
Basin dimensions, m (ft)	3.2 x 5.48	(10.5 x 18)
SWD, rn (ft) •'	3.66	(12)
Detention time,-min ' ....	30	30
Mixer, watt (hp) ; ''	1119	(1.5)
Mixer G factor, sec"^ ¦ .	(variable — 20 to 100)
Secondary Sedimentation
Number of units	11
Basin dimensions, m (ft)	6.4 x 17.4	(21 x 57)
SWD, m (ft)	3.66	(12)
Detention time, hr	2.3	2.3
Overflow rate, rrr/m /day,- (gpd/ft**)	37.36	(918)
Rapid Sand Filtration ,	*
Number of units	2	2-
Filter dimensions, m (ft) "	3.66 x 4.57	(12 x 15)
Filter depth, m (ft)	3.05	(10)
Design loading rate, m3/m^/day (gpm/ft^)-	120	(2)
Support gravel depth, cm (in)	26.67	(10.5)
Coarse sand depth, cm (in)	10.16	(4)
Sand depth, cm (in) ;	60.96	(24)
Surface wash units per filter	2	2
Backwash rate, rrr/m /rnin (gpm/ft^)	0.76	(18.7)

Table 29
Design Flow, m^/day (gpd)	54.5 (14,400) ;
Pressure Filtration
Number of units	1.1 ' .. •
Dimensions - inside diameter, cm (in)	76.2, (30). - .
Overall height, m (ft)	. 1 1.52 (5)
Design,loading rate, m /m?/day (gpm/ft.)	¦: 120 ,(2).
Operating pressure,"kg/cm^ (psi)	•/;<;) S.21, -(75) •, •. ...
Sand media depth, cm (in)	48.26 (19) .
Backwash rate, m^/min (gpm)	0.185, (49),.
Softening •	. >u-
Number of units. ;	1 1 ' -V
Overall dimensions,;;L,W,H, m (ft) 1 &0. x- 0=71 x; 1.77/ : (4.92 ,x„2.33 x 5.83)
Capacity; gramsr(grains) -:	: 16,200 ir;(25P,00Q) f.
Maximum flow-rate, trP/min (gpm)	0.13 (34) ;. = • . r:
¦ • Backwash rate,-; m3/min (gpm)	,. ¦ v , 0.079,: (21).. 'i
Area of bed. (ft^)	0.4 (4.28)
Ion exchanger, m3 (ft )	0,27 (9.5)
Salt tank refill, kg (lb)	272 (600)". .
Regenerations per refill	• .„6 6	. •
Salt per regeneration, kg (lb) ,f .	, 45'. (100)" / _ ••
the resultant precipitates. The water is then recarbonated by the addition of
carbon dioxide which lowers the pH. Recarbonation is accomplished using "a
swimming. pool . type injector chlorinator. Upon recarbonation . additional
precipitates are formed. Ferric sulfate added before the secondary flocculation-
sedimentation unit" will help remove'these fine •precipitates.' •" ' *
After the water is settled the pH receives, finall', carbon
dioxide addition. The water is then filtered and pumped into the': distribution
system. Disinfection with chlorine can be accomplished at two:"different points.
The design data for this plant are presented in Table 30. " *
d. Iron and Manganese Removal. A i.5-mgd water treatment;plant was
designed to supplement an existing facility for the City of Cape Girardeau,
Missouri. Raw water is taken from a well near the Mississippi River and treated
in a water treatment plant that provides iron and manganese removal. The iron
concentration is as high as 14mg/l which exceeds the proposed secondary

Table 30
Design Flow, m^/day (mgd)	2271	(0.6)
Number of units	1	1
Type - induced draft	- - 	-	; . .
Tower dimensions; m (ft)	. 1.22 'x 1.22-.-'	•" (4 x 4)
Sidewater depth (SWD), m (ft)	" ¦ 4.26	(14)
Blower capacity, im^'/min (cfm)	28.04	(990)
Solids Contact •	J"... . ^
Number of units	" 1	1
Basin dimensions, m (ft)	4.57 x 4.57	(15 x 15)
SWD, m (ft)	3.66 '¦	(12) '
- - Up flow-rate-, m^/m?'/rh"in '(gpin/'ft^j	•" -'v 0.055-	(1 .-35)
Minimum detention time in floe zone, min	30	30 "•••¦
Dimensions flocculation zone,	-3.55-	(1 1,65)
top DIA, bottom DIA, m (ft)	: 1.27,3.28	(4.16, 10.75)
Mixer, watt (hp)	¦ ' 560	(0.75)
Number of units *	1	1" " '
Retention at design flow, min	.74	"74
Overflow rate, m'/m^/min (gpm/ft^)	" 0.045	(1.11)
Basin dimensions, m (ft)	4.57 x 4.57	(15 x 15)
..SWD, m (ft), , . .	, 3.35	(11) .
Gravity Filtration ,, . ,, r, . .	... ,	— * - •
Number of units "	2	2
' f Filter dimensions, m (ft)	2,44 x i.83	(8 x 6)
•. • Filter depth, m (ft) . ^	¦ ' 1.83 ¦	(6)
Design loading rate, m^/'m'/min (gpm/ft ) . ,0.105 .	(2.6)
Support gravel depth, cm (in)	25.40	(10)
Sand depth, cm (in)	68.58	(27)
Surfdce wash units"per filter	' 2	2
• ¦ 1 Backwash rate, m /m /min (gpm/ft	) : 0.76 '	(18.7) ¦
Sludge Drying Beds
Number of cells .	, 2".	2
Surface area per cell, m (acres)	526	(0.13)
Maximum sludge depth, m (ft)	0.46 - 0.61	(1.5-2.0)
Embankment slope, horzivert	1 1:3	1:3

drinking water regulation for iron of 0,3 mg/1. Although the water is quite
hard, softening is not practiced.
The presence of iron' and manganese in water is objectionable primarily
because the "precipitation of ""the 'metals " alters the appearance of the water,
turning it a turbid yellow-brown to black. The deposition of these precipitates
will cause staining of plumbing fixtures and laundry. The presence of iron and
manganese in water supplies can* also promote growth of microorganisms in
distribution systems. These growths will reduce pipeline carrying capacity and
may clog"'meters and valves. Higher"Concentrations of iron and manganese will
impart a metallic or medicinal taste to the water.
The major treatment ^facilities 'include" one aerator, one flocculator-clarifier
basin, ¦ rapid-mix;-five.,pressure-filters,—and-provisions for chemical addition. A
' schematic of the treatment plant facilities is shown on Figure 4.
Iron and manganese removal will be achieved by oxidation with air,
chlorine, and potassium permanganate. Oxidation transforms the relatively
soluble forms of iron and manganese to insoluble forms. The insoluble forms
can be removed by sedimentation and filtration. Bimetallic polyphosphate is
added after filtration to aid in corrosion control and water stabilization.
Chlorine is added before and after filtration for oxidation and disinfection,
respectively. Design data for the plant are presented in Table 31.
2. Package Plants '	•
A package water treatment plant is a complete treatment system
composed of two or more integral unit processes. for the removal of one or
more contaminants. Package plants are factory assembled and generally skid
mounted so that installation at the site consists of connecting raw and finished
water lines along with the electrical, service. In moderate to cold climates the
package plant should be enclosed in a building with adequate ventilation and
heat. Factory construction of package plants makes them economically
attractive when compared to plants constructed at the site. Even though
package plants are designed for automatic operation they still need periodic
attention .to monitor the process, maintain' chemical solutions, and perform
required maintenance. Too often in the past package plants have been installed

17" ?(,-*-«


Table 31
Design Capacity, m /day (mgcl)	5677 (1.5)
Number of units	1 1
Type-induced draft
Dimensions, m (ft)	2.44 x 2.44 (8. x 8)
Sidewater depth (S\^D), m (ft)	4.26 (14)
Loading rate, m /m^/min (gpm/ft )	0.65 (16)
Fan motor, watt (hp)	'560 (0.75)
Blower capacity, m /min (cfm)	110 (3900)
Number of units	1 1
Dimensions, dia,. m (ft) 10.97 (36)
SWD, m (ft)	4.26 (14)
Overflow rate, m^/rrr/day (gpm/ft^)	0.04 (1)
Retention time - Sedimentation.min	94 94
Flocculator—Pulsator Type
Pressure Filter
Number of units	5 5
Dimensions, dia, m (ft)	3.05 (10)
SWD (minimum), m (ft)	1.52
C* 'manihf \	Pi £Q
Capacity, nr/mm (gpm)	0.89	(235)
Loading rate, in /m*"/min (gpm/ft")	0.12	(3)
Support gravel depth, cm (in)	25.4	(10)
Manganese greensand media depth, cm (in)	76.2	(30)
Anthracite media, effective size, mm	0.85-120	0.85-120
Anthracite media depth', cm (in)	20.32	(8)
Maximum backwash capacity, m /m /min
(gpm/ft2)	0.49	(12)
and expected to operate completely unattended resulting in unsatisfactory
performance. Properly selected, operated, and maintained package plants can
perform as well as plants constructed on site.
In addition to complete package plants, various unit processes are available
ready for installation at the site. Ion exchange and membrane processes are
examples of package unit process equipment. These unit processes have been
discussed previously in section IV.

Four common uses of package plants, as discussed in the following
paragraphs, include turbidity removal, taste and odor control, softening, and
iron and manganese removal.
a. Turbidity Removal. Package plants designed for turbidity removal
can treat water with a turbidity up to 200 JTU.
. : , Each plant provides;, chemical feed systems,, mixing, sedimentation,
filtration, and .disinfection. Package: plants of this type; i.e., which provide
¦clarification, and filtration can also remove various inorganic contaminants. A
comparison of the design features of package water supply treatment, systems
from three different manufacturers is presented in Table 32.	' " :
. ¦¦}„.:	¦ ' ¦	~ i : Table 32 < .. ¦ :¦	. "
Processes ;
Flow Rajige, m^/da*y
Skid Mounted
Mixing-Type. .
• Sedimentation .
..-Rate,- m^/mt/day
... ,..(gpm/ft2)
Mixing '
Flocculation .
Tube Settlers
2-1/2° or 60°
Pump suction
pulls water
through filter
Disinfection 1
(0.007-0.28) .
Hydraulic.-; : ¦
Tube Settlers
60° Chevron
Standard bed
or dual
120-210 ; -
Mixing "
Flocculation .
Disinfection *
(0.04-0.28). ;
Solids Contact
¦ .',r >.

b. Taste and Odor Control. Taste and odor , causing substances can be
effectively treated using package plants, which utilize either activated. carbon
for adsorption, potassium permanganate for oxidation, or a combination of.
these two chemicals. Powdered activated carbon can be fed either at the same
point as the coagulation chemicals or directly .to the filter. The point of
application will depend upon the nature, and concentration of substances to be
adsorbed. Some substances are adsorbed quite rapidly, suggesting that the
activated carbon should, .be. applied:- directly' to. the. .filter. However,. only small
dosages of activated carbon .should .be -used to, prevent excessive-.:head: loss' and
potential passage* of: the carbon.-through the filter. .Much, .of the carbon* fed "to
the raw water is not effective in-removing dissolved taste and odor because it as
tied up with alum floe and turbidity. In certain instances,-.greater carbon
contact time is required necessitating carbon application to the incoming raw
water. Potassium permanganate could be fed along with the coagulation
chemicals in the rapid mix unit to oxidize tastes and odors. Potassium
permanganate would be added in place of activated carbon.
	c. Softening;* "Package plants designed" for turbidity removal can. be used
for partial softening. Lime is fed to the rapid mix unit and there are no
provisions for recarbonation or a second stage lime addition. The limited .waste
solids handling capabilities restrict the amount of softening that "can be
accomplished. Partial softening presents the potential problem of calcification
of the .filter, media and tubes. Certain maintenance steps must be taken to
prevent calcification from becoming a serious problem. This use of the package
plants would not be generally recommended.	'	-
d.. Iron and Manganese Removal. Package treatment plants'"designed for
turbidity removal can also be used for iron and manganese removal; Either
potassium permanganate or a chlorine solution can be fed to the rapid mix to
oxidize the iron and manganese. The precipitated iron and manganese arc then
coagulated and removed in a manner similar to the removal of turbidity with
sedimentation and filtration.
To reduce chemical costs another type of package plant for iron and
manganese removal is available. This plant uses aeration followed by filtration
as the treatment system. Induced draft aeration is followed by gravity filtration
while pressure aerators and filters are used together. This type of iron and

manganese removal system should not be used when the concentration of either
contaminant is high. An iron concentration of several mg/1 may cause the filter
to plug up resulting in short filter runs. Concentrations of manganese of about
one mg/1 and above may not be fully oxidized by air alone; additional
treatment would be required.

1. ' LinviI G. Rich, Unit Operations of Sanitary Engineering. Wiley, New. York,
- 1961-;
ASCE, AWWA, CSSE, Water Treatment Plant Design, A WW A, New York,
ASTM, Metric Practice Guide, E-380, Philadelphia, 1972.
American Water Works Association. Water Quality and Treatment, 3rd edition,
McGraw-Hill, New York, 1971.
Be Hack, Ervin, Fluoridation Engineering Manual, U.S. Environmental Protection
Agency, 1972.
Clark, Viessman and Hammer, Water Supply and Pollution Control, 2nd edition,
International Textbook, Scranton, 1971.	«
Control Options for Organic Chemical Contaminants in Drinking Water, Federal
Register, Vol. 41, No. 136, July, 1976.
Gulp, Gordon L. and Culp, Russel L., New Concepts in Water Purification,
Van Nostrand, New York, 1974.
David Volkert and Associates, Monograph of the Effectiveness and Cost of
Water Treatment Processes for the Removal of Specific Contaminants, 68-01-1833,
U.S. Environmental Protection Agency, August, 1974.
Great Lakes - Upper Mississippi River Board of State Sanitary Engineers,
Recommended Standards for Water Works, Health Education Service, Albany.
New York, 1976.
Haney, Paul D., "Brine Disposal from Cation-Exchange Softeners," Jour A WW A,
41:829, 1949.

Steel, E. W., Water Supply and Sewerage, 4th edition. McGraw-Hill, New York,
U.S. Environmental Protection Agency, Interim Treatment Guide for the
Control of Chloroform and Other Trihalomethanes, 1976.
Weber, Walter J., Physicochemical Processes for Water Quality Control, Wiley-
Interscience, New York, 1971,

If an existing water treatment plant cannot comply with the maximum
contaminant levels for drinking water, upgrading the facility should be
considered. Various methods of upgrading existing facilities are available.
Uppading techniques suitable for small water treatment facilities are discussed
subsequently. Included are physical, chemical, and operation and maintenance
When upgrading existing facilities is considered, the use of a polymer to
aid the coagulation, sedimentation, or filtration processes should be evaluated.
Polymer addition can improve water quality through increased process
efficiency at relatively low capital cost.
As coagulant aids, polymers increase the size and thus the settling rate of
floe. This is accomplished by adsorption, charge neutralization, and bridging
between particles. For maximum efficiency, the type of polymer, dosage and
point of addition must be determined for each application. Most polymers are
• expensive but only small dosages are required, generally in the range of 0.1 to
1.0mg/l. Proper dosage and the right polymer, as determined by jar or pilot
tests, is. of importance because an excessive or insufficient dose, or the wrong
polymer, can produce a poor floe.
Polymers, used as filtration aids, increase the strength of the floe and
thereby lengthen filter-runs and reduce the incidence of turbidity breakthrough.
Required doses are small, generally less than 0.1 mg/1. Testing must be
performed to. determine the optimum dose of polymer for use as a filtration
aid. The optimum dose exists when the terminal headloss -is reached
simultaneously with the first sign of increasing filter effluent turbidity. When
used, to improve filter efficiency, polymers should be added directly to the
filter influent. Filtration aids should only be used in those filters having-surface
wash equipment or air/water backwash facilities to insure, removal of the deeper

penetrating floe during backwash. The polymer used as a filtration aid will not
normally be the same type which may have been used as a coagulation or
settling aid.
There are a number of commercial polymers currently available. Either
naturally occurring or synthetic polymers can be used. Polymers are available
in both dry and liquid forms. Since the dry polymers are not easily dissolved,
special'mixing and feeding equipment is required. Liquid polymers can be fed
with1 metering pumps and then educted to the point of application. Polymers
are also discussed in section IV A4. Clarification.
Existing rapid sand filters may be converted to dual or mixed media filters
by replacement of the existing single media. Some structural modifications may
be required to allow adequate media expansion during backwash.
:> The most common type of dual media filter consists of a coarse to fine
arrangement of anthracite coal and sand. Primary benefits of dual'media filters
'compared to conventional rapid sand filters are longer filter runs and improved
finished water quality. Dual : media filters are discussed in detail in
.section IV A5, Filtration.	;	-	"	'
Typical mixed media filters contain coal,;sand and garnet in a coarse to
fine configuration. . Mixed . media filters have several; advantages over
conventional, rapid sand filters including; higher capacity, capability,;to filter
.poorer quality influent, and longer filter runs. Use of mixed media filters will
provide, optimum, filtration efficiency and will produce lower finished water
turbidities than single or dual media filters. Additional information on mixed
media filters is discussed in section IV A5, Filtration.
-i	. i/: .r ?•	i •.	• - ' -
. Granular .activated,, carbon can be..used in conjunction with conventional
filtration as a method for upgrading an existing treatment facility. A layer of

activated carbon may be used to replace most of the sand in a conventional
filter; most states require some minimum depth of sand under the carbon.
Activated carbon may also be used to replace coal in dual media filters. When
used as a filter media replacement, activated carbon functions as both a
turbidity removal and adsorption unit. Finished water quality can potentially
be enhanced without construction of additional filters or carbon columns.
Detailed information on granular activated carbon is provided in section IV A3,
Adsorption. For most taste and odor removal requirements a contact time of 5
to 7-1/2 minutes is acceptable. Haloform or haloform precursor removal
requires a contact time of 12 to 15 minutes. Replacement of a portion of the
filter media with granular activated carbon could reduce the plant capacity.
Each potential application of media replacement by granular activated carbon
should be evaluated by a knowledgeable engineer.
Effective coagulation, involves intimate mixing of the. coagulant and the
water. Existing water treatment plants with inefficient or overloaded rapid mix
facilities or without any means for coagulant mixing, will not..effectively
remove, turbidity or other contaminants -from, water;'If; chemical mixing by
means of pumps is currently utilized, the chemicals may adequately
mixed because of failure to achieve uniform distribution. Existing rapid mix
chambers without mechanical mixing should also be evaluated. Baffling alone
may not provide adequate coagulant mixing. Mechanical rapid-mix1 provides a
controlled, efficient unit process for the mixing of chemicals with the water
being treated. Addition of or improvement to rapid mix 'facilities will aid the
clarification process and thus- improve finished water quality. Additional
information on rapid mixing is contained in section IV A4, Clarification.
Flocculation is a principal mechanism in removing turbidity and various
other contaminants from'water. Inefficient or overloaded fioceulation facilities

should be upgraded. If an existing treatment plant has rapid mix and
sedimentation facilities without flocculation. the addition of flocculation
facilities could enhance finished water quality. Flocculators that use only .
baffles for mixing usually perform well at only one flow rate. Provision of
variable mechanical mixing will enable the flocculation process to be effective,
for,, varying flow rates. The flocculation process is-, discussed in detail in,
section IV A4, Clarification.	;
• Upgrading existing - water treatment facilities, may involve.-change of a
chemical currently. used or use of a mew chemical. For . example, if iron and
manganese removal: is.-.-.desired, and only, aeration is-being-used-, addition • of.,
chemical oxidation will improve removal of manganese. Laboratory: and plant
scale tests may be used to select a coagulant better suited ;to the raw water
quality. A coagulant aid or filter aid may also be used as discussed previously.
Another method to be considered when upgrading water treatment facilities is
chemical* Addition for pH adjustment to prevent corrosion in the system.
G.	TUBE SETTLERS ••• • •• • • •": ' • • • r-' • -	;
An economic alternative to construction of additional sedimentation basins ,
is installation of tube settlers in existing sedimentation basins. Use of tube
settlers in this manner will produce an effluent of higher quality than is possible
by using the existing basin, only,	... <'	: J]
Two basic tube settling systems are currently utilized; (1) parallel 5 cm
(two inch) square: tubes inclined at 60° ; from the horizontal, and (2) parallel
2.54 cm (one inch), hexagonal tubes inclined at 5° from the horizontal. In the
60°.inclined tubes, the" sludge slides down the tubes and is collected beneath
them. The 5° inclined tubes must be cleaned by backwashing with filtered,
water as the basin is drained.

When tube modules are installed, they should not be located near areas
where turbulence could reduce their effectiveness. In horizontal flow basins, the
inlet end should remain uncovered by the tubes to allow inlet velocity
dissipation. In radial flow basins, the required modules can be placed in a ring
around the basin periphery, leaving an open area to dissipate turbulence. The
top of the tubes should be located 0.6 to 1.2 m (2 to 4 ft) below the water
surface. In general, the 0.6 m (2-ft) minimum should be used in shallow basins.
The 1.2 m (4 ft) submergence is used only in basins with a sidewater depth of
5 to 6 m (16 to 20 ft). These settling modules may utilize radial support beams
in circular basins or support beams spanning the width in rectangular basins. In
basins which have radial launders, it is often possible to suspend the.modules
from the launders.
In some cases there is a tendency for floe build-up to eventually bridge the
tube openings and a blanket of solids on top of the tubes results. Methods of,
removing this accumulation include lowering the water level-of the basin below;
the top of the tubes or occasional use of a water stream or compressed air to
flush out the attached floe. • . •	.. ¦
Recommended tube settler, loading rates range , from 120 - to.
'n	'¦5	'		
240 nr'/m ,/day (2 to 4 gpm/ft^). Selection of a specific overflow rate depends.
on existing clarifier configuration, water temperature, existing clarifier overflow
rate, and desired effluent turbidity. More detailed information relative to the
size, capacity, and configuration of these settlers, and their adaptability to
existing sedimentation basins, may be obtained from manufacturers of such
equipment. The use of tube settlers for a particular application should be
evaluated by an'engineer.	... -. . . •
When upgrading water treatment, facilities is necessary,* hydraulic
conditions of existing basins may be improved by use of baffles, by modifying
inlet: and outlet conditions, or by reducing pipe velocities below 0.6:m/'sec.
(2 ft/sec). •

Either horizontal or vertical baffles may be used to prevent short-circuiting
in floceulation basins. Judicious baffling may be added as required or existing
baffles rearranged to enhance flocculating conditions.	.
Properly "designed inlets and outlets are also necessary to avoid
short-circuiting through a 'basin. Inlets must be designed to'distribute the water
uniformly over the cross section of each basin. Adequate outlets must be
provided to prevent excessive overflow rates and consequent breakup of floe or
suspension,, of settled solids from floor of basin. Freely discharging ;weirs.have a
tendency to break fragile floe.. Therefore, submerged weirs are recommended to
provide' an 'effective outlet arrangement. Inlet and outlet arrangements are
discussed in more detail in section IV A4, Clarification.
When uppading an existing facility is considered, plant piping should be
reviewed in regard to its, configuration and to the velocity of flow through it.
Velocities in piping following floceulation should , not exceed 0,6 m/sec
(2 ft/sec) to reduce floe breakup because of turbulence. Excessive bends, drops,
etc. also increase turbulence, and thus enhance floe breakup.
Regardless of how well.a water treatment plant is designed, if,not
operated and maintained correctly, the treatment.process or processes will-not
perform effectively. Therefore, upgrading various. aspects of plant operation
and maintenance is. a prime consideration.
1. Operator Training and Qualifications
Even in the smallest plants with the simplest types of treatment, only
qualified personnel should be. in charge. Where .experienced operators are not
available locally to control the operation of a. water treatment plant, a qualified
operator should be employed from outside the community or a local person
should receive adequate training to become a properly certified operator.

Training courses may be used as a means of upgrading an operator's
qualifications. It is recommended that operators participate in training courses
' on a regular basis, as advancements in the' knowledge and techniques of
treatment processes are constantly being made. Locally 'available in" almost
every state, these courees are sponsored by the state departments of health,
universities, and state and national technical associations.
In addition to training courses, numerous states utilize an operator
certification program as a' means of providing improved plant operation arid to
enhance the professional status of water plant operators. Currently, 39"states
have a mandatory certification program, nine states have a voluntary program arid
two'states have no certification program. '
Another method of improving the operation of a water treatment plant
'"'involves employing ' an' engineer or an operator" from a ia'rger facility as a
consultant. Also; one operator might be employed by several small plants!' The
operator would rotate from plant to plant as required. ' ¦
2. Improved Monitoring and Surveillance
The purpose of making analyses and tests is to control treatment* record
performance, comply with regulations, and indicate means for improved
performance. Control tests should be used to show that the water has been
properly prepared for each major process, that each 'process is' performing
effectively, and that the finished water quality is adequate. Accurate metering
of "¦ both water "and' chemicals is' nedessary"because inaccurate feeding of
chemicals could be economically wasteful and' potentially hazardous to the
health of the community.
As an aid in upgrading plant "performance, the" following control tests can
be used:
¦ •••; ¦"	.* Continuous ¦Turbidity-Monitoring-' ; -• *•« -:i;
< .• •; ¦' "Chlorine'Residual	.-yz,
r	.. ^Alkalinity-=	:'>•

Use of the following equipment can be used to assist the operator in improving
plant performance:
Raw water and plant effluent meters
Filter control
Raw water and,plant effluent turbidimeters'
Residual chlorine recorder
Control tests, metering, instrumentation, and control are discussed in more
detail in section IV B, Water Quality Control.
In addition to water quality monitoring on the plant site, samples taken
regularly from the distribution system should be examined to ensure that
applicable drinking water regulations are met and to ensure that the water is of
high quality when it reaches the consumer.
As discussed • in section IID. Alternatives to Treatment, physical
consolidation of facilities may be desirable for some small water treatment
systems. However, regionalization of treatment or distribution facilities is
neither feasible nor desirable for all small water systems. Other aspects of
regionalization should be considered in an attempt to upgrade existing facilities.
For example, management and administrative functions could be combined;
county, parish or township public service districts could be formed to operate
and maintain several facilities; and a central laboratory could be used by
several small water systems.

Water and Resources Management Committee, Survey of State Programs and
Attitudes on Regionalization for Public Water Systems, Environmental
Engineering Division,''American'Society of Civil Engineers, April, 1977.


Initial investment costs and operation and maintenance costs are presented
herein for conventional water treatment facilities and for package water
treatment plants. The cost curves are intended to assist in evaluating proposed
new facilities and modifications to existing facilities.
Key to the development of these costs is the relationship of population to
water consumption. Provided in Table 33 are the water use projections used in
this report.
Table 33
Plant Per Capita
Design Rate
Design Plant

m /c/day
¦ 25
The plant per capita design rates in Table 33 are based on water usage or
usage rate and on an assumed amount of storage in the system. For the smallest
svstem, no storage was assumed in the system; therefore, the plant design rate
is based on the maximum rate of usage which would be for watering lawns or
gardens. For the largest system,* a normal maximum day per capita usage was
assumed along with adequate storage in the system to supply any water require-
ments which would exceed this rate.
Cost data presented are appropriate for average situations. They should
permit development of preliminary cost estimates for water treatment facilities

when used with judgment regarding local conditions. An engineer should be
engaged to review local conditions and to evaluate the manner in which this
report's cost information will be .used.
It is emphasized that the cost data contained in this report cannot be used
as a substitute for detailed cost estimates based on a particular water treatment
situation, Among the many variables, which affect actual construction costs are
the following:
(a)	.Characteristics and complexity of specific plant design.
(b)	'Current and projected labor costs.
(c)	Contractors' attitudes regarding their need for work.
(d)	Availability of materials.
(e)	Climate and seasonal factors.
Local factors can also have a significant effect both on construction and on
operation and maintenance costs.
It is essential that the user of the cost estimating methods presented in
this report review all introductory material. In particular, the information
discussed at the beginning of, section VI A, Capital Costs, and section VI B,
Operation and Maintenance Costs, should be understood prior to use of the
cost curves, and tables.
For the most part, each cost curve extends from 227 m^/day (0.06 mgd) to
5680 m^/day (1.5 mgd). Exceptions are the cost curves for diffused aeration,
clarification processes, -filtration, disinfection methods, and package plants. In
general, diffused a re a ti on is not economical for treatment plants with design
flows less than 1890 m^/day (0.5 mgd).
For small water treatment systems, the most applicable range for
clarification, filtration and disinfection unit processes overlaps with the most
applicable range for package plants. This situation is reflected in the cost
curves. The solid portion of each cost'curve indicates the most applicable range
for that unit process or package plant. The dashed portion of these cost curves
indicates the plant design flow range in which conventional unit processes or
package plants might be utilized.

Cost curves were -developed for treatment processes judged applicable to
small water treatment systems. These curves relate capital costs to quantities of
water treated and to population served. Estimates of complete water treatment
plants or additions to existing plants'may be developed on the basis of-these
Yard piping, fencing (where applicable), and sitework have been-included in
the curve for each unit process. When adding unit process costs together some
of these items may overlap; this may cause the total cost to exceed actual plant
costs by 10 to 25 per cent. -	; •	•' •'
Cost data, developed specifically for this report, are based on information
from various manufacturers and on the. experience and judgment of the
investigators. Preliminary designs and engineering cost estimates were developed
for each unit process at various low rates. Estimates of -construction costs are
representative of average price levels as of January, 1977. The Engineering-News
Record Building Cost Index of that date had a value of 1489.
Included in the capital costs are necessary construction costs, a
contingency amount and engineering, legal and administration - fees; A cost for
fencing is provided- for mechanical 'aeration, diffused aeration, rapid mix,
flocculation, sedimentation, ozone contact chamber and waste disposal
(lagoons). For each of the other treatment methods an enclosure is
recommended and separate cost curves are provided.	'
• Capital- costs for unit proceses. package plants and enclosures are
developed as follows:	• : r- •.
(1) Construction cost — included are necessary costs for equipment,
materials, installation, freight and start-up.. .	'
(21 Sitework — estimated as 10 per cent, of the construction cost..,
(3) . Electrical — 20 per cent of.the construction cost. •- -

(4)	Contingency — estimated as 10 per cent of the total of construction
cost, sitework, electrical and fencing (if applicable).
(5)	Engineering, legal and administrative — estimated as 15 per cent of
the total of construction cost, sitework, electrical, fencing (if
applicable), and contingency.
Equipment and materials capital costs are based on use of prefabricated,
modular, or factory built/field assembled units to minimize on-site construc-
tion. Design parameters used for sizing unit processes should not be generally
applied to all water treatment situations. Design parameters should be selected
on the basis of raw water characteristics for each application.
Enclosure capital costs include costs for a prefabricated insulated metal
building, foundation, and necessary plumbing and electrical facilities.
Separate cost curves for enclosures and treatment facilities have been
provided to allow the enclosure cost to be deleted where climate would not be
detrimental to treatment process efficiency or equipment integrity. It must be
recognized, however, that the enclosure cost curve includes the foundation.
Therefore, if art enclosure is judged not necessary for'a specific situation, then
a foundation cost must be added to the capital cost for the treatment process
in question. •
Capital costs for laboratory facilities are not provided in "this section of
the report, but are given in section IV B2, Laboratory Facilities. Estimates of
construction costs do not include costs for high service pumping, treated water
storage or extraordinary costs related to large amounts of rock excavation, site
dewatering or piling.
1. Unit Processes
. " Figures 5 through 33 are the capital- cost curves for various water treatment
unit-processes/'Prior-to use of the cost curves," the estimator should carefully
review the following summaries , of equipment, material, and design criteria used
in developing the unit process capital costs. If local conditions require use of
different design criteria or equipment, the capital costs must be revised

An example calculation illustrating use of the unit process capital cost
curves is provided in section VI C.
a.	Mechanical Draft Aeration, Capital costs for this aeration process
are based on an induced draft aeration unit located above a basin. The
following design criteria are used to develop capital costs for mechanical draft
(1)	ten trays vertically spaced approximately 0.305 m (12 in) apart.
(2)	tray area furnished is 3.9cm^ per m^/day (40 ft^ per mgd).
(3)	air supply rate of 0.019 m /min per m /day (2,500 cfm per mgd).
Capital costs for this unit process include costs for the following
equipment and materials: prefabricated aluminum induced draft aeration tower,
blower, motor, basin, foundation, necessary controls., associated valves and
piping, and fencing. Refer to Figure 5 for the mechanical draft aeration capital
cost curve.
b.	Diffused Aeration. Diffused aeration capital costs are based on a
system which consists of an aeration tank and the means of supplying
compressed air to this tank. The following design criteria are used:
(1)	basin depth of 3 m (10 ft).
(2)	basin width from 3 to 6 m (10 to 20 ft).
(3)	width to depth ratio less than 2:1.	-	...
(4)	retention time of 20 minutes.
(5)	air supply of 0.67 m^ of air/m^ of water (0.09 ft^/gal).
The following equipment and materials are included in the diffused
aeration capital cost curve: steel aeration tank, foundation, positive displace-
ment air compressor and motor, air piping; air diffusers, inlet filter silencer,
necessary controls, associated valves and-piping, and fencing. Refer to Figure 6
for the diffused, aeration capital cost curve.

c.	Activated Carbon Beds. For the activated caibon adsorption process,
capital costs are based on a fixed-bed gravity feed system which uses an 8x30
mesh size granular carbon. Also included is an empty tank for storage and
dewatering of the spent activated carbon. To develop the activated carbon bed
capital cost curve, the following design criteria are used:
(1)	media depth of 1.2 m (4 ft),
(2)	surface loading rate of 160 m^/m^/day (2.7 gpm/ft^).
(3)	contact time of 11.25 minutes.
(4)	three cells, each handling one-third of the total flow.
The capital cost curve for activated carbon beds is based on costs for the
following equipment and materials: prefabricated steel three-cell gravity filter
shell including underdrain system and supporting gravel, activated carbon,
surface wash system, backwash system, spent carbon storage tank, necessary
valves, piping and manual controls. Refer to Figure 7 for the activated carbon
bed capital cost curve, along with a capital cost curve for an enclosure.
d.	Activated Alumina Columns. Capital costs developed for the
activated alumina adsorption process are, ¦ based on a duplicate-column,
gravity-feed system using grade F-l. 28x48 mesh size alumina. Also, included in
these capita] costs are facilities for i eg en era ting the alumina. Regeneration
involves backwashing with raw water, sodium hydroxide and sulfuric acid. To
prepare the activated alumina column capital cost curve, the following design
criteria are used: -
(1)	media depth of 1.07 m (3.5 ft).
(2)	surface loading rate of 180 m^/m*/day (3 gpm/ft2).
(3)	contact time of 8.7 minutes, .
(4)	two cells, each handling one-half of the total flow. -
The following equipment and materials are "included in the activated
alumina capital cost curve: prefabricated steel shell, underdrain system,
activated alumina, supporting gravel, surface wash system, backwash system,

associated valves and piping, necessary manual controls, chemical feed system
and storage tank for each of the regenerative chemicals, and a mechanical mixer
for the sodium hydroxide storage tank. Refer to Figure 8 for the activated
alumina capital cost curve, and the capital cost curve for an enclosure.
e.	Rapid Mix. Capital costs for the rapid mix process are based on a
mixing basin with a flash mixer and a by-pass pipeline with a static mixer. The
static mixer is provided as backup for use when the mixing basin or flash mixer
is out of service. The volume of the mixing basin is specified by the retention
time; the velocity gradient determines the power needed by the mixer. To
prepare the rapid mix capital cost curve, the following design criteria are used:
(1)	one basin.
(2)	retention time of 45 seconds.	' .
(3)	velocity gradient of G = 750 sec" I
The following is a list of equipment and materials included in rapid mix
capital costs: steel basin, foundation, flash" mixer, metal stairs, metal grating,
mixer support, by-pass pipeline with static mixer, necessary controls, associated
piping and valves, and fencing. Chemical feed equipment is not included in the
rapid mix cost estimates. Section VI A1 (o). Chemical Feed, contains'various
chemical feed system costs. Refer to Figure 9 for the rapid mix capital cost
curve.	•
f.	Flocculation. The flocculation process capital costs are based on
utilizing vertical turbine flocculators in the flocculation basins. The retention
time determines the volume of the basin. The power of the vertical turbine
flocculator is calculated from the velocity gradient (G), The following design
criteria are used:	¦
(1)	retention time of 30 minutes.	-
(2)	velocity gradient of G = 50 sec"'-
(3)	two basins, each handling one-half of the total flow.
(4)	one vertical turbine flocculator per basin.

Capital costs for flocculation include costs for the following equipment
and materials: steel basin, foundation, vertical turbine floceulator, influent and
effluent devices, metal stairs, floceulator support, metal grating, necessary
controls, associated valves and piping, and fencing. Refer to Figure 10 for the
flocculation capital cost curve.
g.	Sedimentation. Capital costs for the sedimentation process are based
on a sedimentation basin sized to allow settling of coagulated particles and
furnished with equipment for removal of the waste solids. The following design
criteria are used to develop the capital cost curve for the sedimentation
. . . (1) retention time of 4 hours.
1 9	"J
(2)	surface loading rate of 16 m /m /day (400 gpd/ft ), - .
(3)	two basins, each handling one-half of the total flow.
Sedimentation capital costs include costs for the following equipment'and
materials: steel basin, foundation, mechanical waste solids collection equipment
and support, submerged orifice peripheral weir, metal grating, necessary
controls, associated piping and valves, and fencing. Refer to Figure 11 for the
sedimentation capital cost curve.	:
h.	Flocculator-Clarifier; Flocculation and sedimentation can both be
achieved in a, flocculator-clanfier. Design criteria used to develop the
flocculator-elarifier cost curve are as follows:
(1)	.flocculation zone retention time of 30 minutes.
(2)	sedimentation zone surface loading rate of 16 m ;'rn-/day
(400 gpd/ft2).
, (3) two basins, each handling one-half of the-total flow.
The flocculator-clanfier capital cost curve includes the following
equipment and materials: steel basin,, mechanical waste ..solids
collection' equipment and support, vertical turbine floceulator, submerged,
orifice peripheral weir, metal stairs, metal grating, necessary controls, associated

piping and valves, and fencing. Refer to Figure 12 for the flocculator-clarifier
capital cost curve.
i. Ion Exchange Softening, Capital costs for the ion exchange softening
process are based on a complete softening system. This system includes
facilities for blending softened and raw water, and facilities for automatic
backwash and regeneration. Design criteria used to develop the capital cost
curve for ion exchange softening are as follows:
(1)	softening 75 per cent of the plant flow and blending with the
remaining raw water.
(2)	automatic regeneration and backwash triggered by time?clock control.
Capital costs for ion exchange softening include costs for the following
equipment and materials: complete ' ion exchange softening system with
automatic controls, associated valves and piping, cation exchange resin, brine
tank and necessary regeneration equipment. Refer to Figure 13 for the ion
exchange softening capital.cost curve and an-enclosure capital cost curve. • • ¦
j. Pressure Filtration. Pressure filtration capital cost curves7 are
developed for three surface loading rates. Costs are: based on multiple -unit
filters with automatic control of the backwash cycle. The following design
criteria are used to develop capital costs.for pressure filtration: -
(1)	surface loading rates of 120, 240 & 360 m?/m~/day. (2, 4, &
6 gpm/ft2).
(2)	three to seven filter cells, each cell handling an equal portion of the
plant flow. . ¦	•••	: :
The capital cost curves for pressure filtration are based on the following
equipment and materials: multiple package"pressure filters',-associated* valves
and piping, automatic controls, surface wash system,. backwash system, and
media. Variance in "media costs is not significant in the cost of the filter. Refer
to Figure 14 for pressure filtration capital cost curves and enclosure capital cost
curves.	"

k. Gravity Filtration. For the gravity filtration process, capital costs
curves are developed for different surface loadings. Variance in media costs is
not significant in the cost of the filter. Provisions are also included for
automatic control of the backwash cycle. To prepare the capital cost curves for
gravity filtration, the following design criteria are used;
(1)-surface	loading rates of 120, 240 &. 360 m^/m^/day (2,. 4/ &
'	6 gpm/ft^);
(2)	three cells, each handling equal flows.
Capital cost curves for gravity filtration include costs for the following
equipment and materials; package triplicate unit, gravity filters, associated
.valves and piping, automatic controls, surface wash pump,.backwash pump, and
media. Refer to Figure 15 for gravity filtration capital cost curves and-enclosure
capital cost curves,
1. Demineralization. For the demineralization process, capital costs are
based on a two-bed system. This system includes facilities for blending
demineralized and raw water, and facilities for .automatic regeneration-
Regeneration involves backwasliing with sulfuric acid and caustic soda.
The following design criteria were used to develop the demineralization
capital cost curve:
(1)	de'mineralizing 75 per cent of the plant flow and blending with the
remaining"raw water.
(2).	two-bed system.
" (3)' automatic regeneration and backwash triggered by conductivity
¦ (4') .influent TDS of-1000 mg/1 was assumed.
The capital cost curve for demineralization includes costs for the following
equipment and materials: two-bed demineralization system, cation and anion
exchange resins, necessary regeneration equipment, associated valves, piping and
automatic controls. Refer to Figure 16 for the demineralization capital cost
curve and a capital cost curve for an enclosure.

m. Electrodialysis. The electrodialysis capital cost curve was developed
for a complete multiple-stage electrodialysis system. Costs were obtained for
standard units as rated by the manufacturer for operation with a raw water
TDS concentration of 1500 to 4000 mg/1. For these electrodialysis units,
predicted per cent water, recovery ranges from 65 to 85 and predicted; per cent
TDS removal ranges from 82 to 96. Local water quality may change the rated
capacity of these units.
Electrodialysis capital costs include costs for the following equipment and
materials: skid-mounted reverse polarity electrodialysis unit with'membrane
'¦ stacks, rectifiers, low pressure feed pump, brine recirculation pump, chemical
' • cleaning equipment, cartridge filters, necessary valves, piping and _ automatic
¦ controls.- - Refer to Figure 17 for the electrodialysis capital cost* curve. The
enclosure capital cost curve for electrodialysis is shown on Figure 18.
"n. Reverse Osmosis. The reverse osmosis capital cost curve was
developed for a complete reverse osmosis treatment system. Costs obtained
were for standard units as rated by the manufacturer for operation with a feed
of 1500 mg/1 NaCl at 400 psi; 25°C (77° F), and-75 per cent conversion. Local
water quality may change the rated capacity of these units. .
Capital costs for reverse osmosis include costs for the following equipment
and materials: skid-mounted, membrane-type reverse osmosis unit with hollow
' fine fiber membranes,' high pressure pumps, cartridge filters, acid and
polyphosphate feeding equipment, necessary valves, piping and automatic
controls. Refer to Figure 19 for the reverse osmosis- capital cost, curve.
Presented on Figure 20 is a capital cost curve for an enclosure for this unit
o. Chemical Feed. Capital costs have been determined for the following
chemical feed systems:
(1)	powdered activated carbon.	' . : ¦
(2)	coagulants.		
(3)	hydrated lime.			.	: . •

(4)	polymer.
(5)	polyphosphate.
(6)	chlorine.
(7)	ozone.
(8)	calcium hypochlorite. ..	-
(9)	.sodium hypochlorite (purchased).
. (10)	sodium hypochlorite (on-site generation). , .	•
Chemical feed system capital costs include all equipment essential for the
storage, mixing and application of the chemical. Duplication of equipment, i.e.,
a standby system, is not provided,for powdered activated carbon, polyphosphate,
ozone: or sodium hypochlorite (on-site generation) chemical feed systems. Jhe
cost for a standby feeder or metering, pump is included in the chlorine, calcium
hypochlorite and sodium hypochlorite (purchased) chemical feed system capital
costs.. A standby chemical feed system is included, in the coagulant,, hydrated
lime and polymer capital cost curves. For each chemical feed system, separate
capital cost curves have- been developed for selected chemical dosage
concentrations. Figures 21 through 30 show capital cost curves for various
chemical feed systems and their enclosures.
1. . Powdered Activated Carbon. Powdered activated .carbon dosages
used to develop capital ''ost curves for this chemical feed system are 20 mg/1 or
less and 50 mg/1. Refer to Figure 21 for the powdered activated, carbon capital
cost curves and for enclosure capital cost curves.	- - • .
2..' .Coagulants, The .coagulant chemical feed capital cost curve is based
on a system dosage capability of up to 50 mg/1.- Refer to Figure 22 for the
coagulant capita] cost curve and for an enclosure capital cost curve. :
3. Hydrated Lime. Hydrated lime capital cost curves are based on
chemical .feed systems capable of feeding 50. mg/1 or. less, 100 mg/1 and 200 mg/1
of .hydrated lime. Refer. to .Figure 23 for these capital, cost curves and for
enclosure capital cost curves.	;

4.	Polymer. Polymer dosages used to develop capital cost curves are
0.5, 1, 3 and 5 mg/1. Refer to Figure 24 for polymer chemical feed capital cost
curves along with enclosure capital cost curves.
5.	Polyphosphate. The polyphosphate chemical feed capital cost curves'
are based on a system dosage capability of up to 5 mg/1. Refer to Figure 25
for these capital cost curves and for enclosure capital cost curves. " •
6.	Chlorine. The chlorine- chemical feed capital cost curves are based on
selected chlorine dosages of 5 mg/1 and less and 10 mg/1. Shown on Figure 26 are
chlorine capital cost curves and capital cost curves for enclosures.
7/ Ozone", Capital costs for the ozone disinfection process are based"on'
the on-site generation of ozone and its application within-a basin sized to""
provide adequate contact time. Costs included are for air feed ozone generating
equipment.	*" " ' '	' * '*
; The following design criteria are used "for the ozone capital cost 'curves:. .• .• • >
-(1) -contact time of 15 minutes.-	4<;?	._
(2) ozone dosages of 1.5, 5 and 10 mg/1. . "	' "
Capital costs for ozone disinfection include costs for the following
equipment and-materials: ozonator, steel basin, foundation, "metal "stairs, and
fencing for the contact basin. Refer to Figure:27 for the "¦ ozon'e " capital cost:
curves and also for 'enclosure' capital cost "curves. Enclosure capital'costs are
based on enclosures sized only for the ozone" generating equipment.-	:
8. Calcium Hypochlorite. - The calcium hypochlorite chemical feed
capital costs are based on calcium hypochlorite dosages of -1.5, 5 and 10 mg/1.
Refer to Figure 28 for calcium hypochlorite feed system capital cost curves and
enclosure capital cost curves.
¦9. Sodium Hypochlorite.' Sodium hypochlorite capital "cost: curves "are
based on chemical feed systems capable of feeding 1.5, -5 and 10 mg/1 sodium-
hypochlorite dosages. These cost curves are applicable kwhen sodium
hypochlorite is purchased. Refer to Figure 29 for these capital cost curves and
for enclosure capital cost curves.

10. Sodium Hypochlorite (On-Site Generation). The capital costs
developed for sodium hypochlorite on-site generation facilities are based on
using salt in a brine solution as opposed to sea water. Sodium hypochlorite
dosages of 1.5, 5 and 10mg/l are used. Capital costs for this disinfection
process include costs for the following equipment and materials: sodium
hypochlorite generator, brine system, brine tank, and the recycle tank. Refer to
Figure 30 for capital cost curves for sodium hypochlorite on-site generation
facilities and for enclosure capital cost curves.
2.	Laboratory Facilities
A capital cost curve for laboratory facilities is not presented in this report.
A cost curve is not necessary as one laboratory size is .applicable for the range
of treatment facility sizes considered. Refer to section IV B2,. Laboratory-.
Facilities, for a laboratory capital cost.	-..I
3.	Waste Disposal Facilities
Capital costs for a lagoon waste disposal facility are based on disposal of
waste solids from a turbidity removal plant. The following design criteria are used:
(1)	turbidity of 50 JTU,	..
(2)	aluni dosage of 30 rrig/1. -	¦'	¦'
(3)	retention time of 2 years.
(4).	influent waste solids consisting of 5 per cent solids.
(5)	two-cell lagoon.
Capital costs include costs for excavation, inlet, and outlet appurtenances,
seeding and fencing. Refer to Figure 31 for the lagoon capital cost curve.
4.	Package Plants	,	• .
The capital cost curve for package water treatment plants is based on a
complete treatment facility. Included are costs for the following equipment and

materials; coagulant, polymer, and chlorine chemical feed systems; mechanical
flash mixer; mechanical flocculator; sedimentation; filters; surface wash and
backwash systems; steel basins; and necessary valves, piping and automatic
controls. Refer to Figure 32 for the package plant capital cost curve and for an
enclosure capital cost curve.
5. Upgrading Existing Facilities
Section V of this report discusses various methods available for upgrading
water treatment facilities. Capital cost curves for some of these methods are
provided in section VI Al, Unit Processes. Thus, it is not necessary to discuss
them in this section. The rapid mix capital cost curve is shown on Figure 9 and
the flocculation capital cost curve is shown on' Figure 10. Refer to Figure 24
for the polymer (coagulant or filtration aid) capital" cost curves. Cost
information for use of a new chemical is shown on Figures 21 through 30.
Capital costs are not presented for replacement of filter media,' chemical
change or improvement of hydraulic conditions, operator training, or
monitoring'and control as these'are'best determined for'each water'treatment
The only upgrading method to be discussed in detail here is use of tube
settlers. Capital costs for this process are based on installation of settling tubes
in an existing sedimentation basin. The following design criteria are used to
develop capital cost curves for the tube settling system:
(1)	settling tube surface loading rate of 180 m^/m^/day (3 gpm/ft^).
(2)	5 cm (2 in) square tubes inclined at 60° from the horizontal.
(3)	adequate tubes are provided to settle the existing plant {low. "
Capital costs for this method of upgrading water treatment facilities
include costs for PVC settling tubes and the support beams. Refer to Figure 33
for the settling tube capital cost curve.

Based oil the average cost information presented, total annual operating and
maintenance expenses for various plant components may be developed. Where
It was not possible to base operation and maintenance cost data on manu-
facturers* information, cost elements were estimated.
Actual costs may vary appreciably from the estimated average costs in this
report. However, when used with judgment, the data presented should be of
value for preliminary cost estimates. The user should recognize the inherent
limitations of such estimates and should develop applicable operating cost
estimates based on local conditions.
Cost data were adjusted to indicated cost levels for January 1977. To
update these costs, they may be trended to" the applicable date by using the
"Wholesale Prices and Price Indexes" as published by the Bureau of Labor
Statistics," U.S. Department of Labor. The Wholesale Price Index for
January 1977 is 188.4. If knowledge of a specific local situation indicates a
more appropriate updating method, such information should be utilized.
Major elements of operation and maintenance costs considered include
labor, power* supplies and chemicals. Annual labor cost curves are provided for
the following types of treatment facilities:
Type 1 7-;minimal-treatment such as disinfection only.
Type 2 — package plants.
Type 3 —conventional facility with chemical addition, clarification,
•• " filtration and disinfection.
Type 4 — conventional facility described- above, with one additional special
process such as ion exchange, electrodialysis, reverse osmosis,
•;	- activated alumina, etc";
The labor costs indicate the ,total requirements to adequately operate and
maintain the facility. Man-hour requirements- for .-these treatment facilities are
based on desirable levels of operator attention for each type of plant. For the

Type 1 and Type 2 facilities it is estimated that one part-time operator is
required. For the Type 3 and Type 4 facilities, round-the-clock operation with
one to two operators per shift is recommended. The average hourly earnings
rate (wages plus fringe benefits) used is $7.30. This rate is based on the
National Average Earning Rate published by the U.S. Department of Labor,
Bureau of Labor Statistics, for nonsupervisory employees in the public utility
industry, under "Water, Steam and Sanitary Systems", SIC Code 494-7, as of
January 1977. If local conditions indicate a different earnings rate, such
information should be used. Refer to Figure 34 for annual labor cost curves for
Type 1 and Type 2 facilities. Refer to Figure 35 for annual labor cost curves
for Type 3 and Type 4 facilities. ,
Power cost curves are provided for the applicable unit processes and for
package plants. These power costs are based on equipment power requirements,
and estimate of the operating time .of the equipment, a pov^er, cost of
S0.03 per kWh and a 10 per cent contingency. . ..	..
• !- Cost curves for supplies include costs for normal annual, upkeep and
improvement materials. Unit process supply cost curves include costs for oil,
grease, ' belts, chains, etc. 'Enclosure supply cost curves include, cleaning
materials, paint, etc. The supply costs are based on 5 per cent of the equipment
cost for each unit process and package plant, 2 per cent .of the construction
cost for each enclosure,and a. 10 percent contingency. Supplies cost curves for
electrodialysis and reverse osmosis are exceptions. They-are based on estimated
costs from manufacturers. Electrodialysis supplies range in cost from $0.20 to
$0.30 per 3.8 nr (1000 gal), depending on plant size. Reverse osmosis supplies
range in cost from SO.20 to $0.50 per 3.8 (1000 gallons), depending on
plant size.
< • - ' »	'	¦ i - i	. *
Chemical costs are provided in Table. 34 for various chemicals used in water
treatment. These chemical costs are for January 1977 and should be trended as
necessary by using the Wholesale Price Index as discussed previously. "
"» , ' ' ¦ ' ;
Chemicals not listed in Table 34 include: granular activated carbon,
regenerative chemicals for activated alumina, ion exchange softening and
demoralization,- and salt for sodium hypochlorite cin-site generation. Costs for
these chemicals are-provided on cost curves;	i ^ '• '

Table 34
Activated Carbon
65 lb bags
100 lb bags
Calcium Hypochlorite 100 lb drums
Chlorine	100 lb cylinders
Ferric Chloride
Ferric. Sulfate
175 lb drums
100 .lb bags
Hydrated Lime	50 lb bags
Polyphosphate . 100 lb bags
(Sodium Hexameta) *
Polymer (Dry)
' (Wet)'
50 lb & 100 lb bags
55 gallon drums;
i	' '	¦ ¦
110 lb bap
550 lb bags
1-14 bags, 44.45 cents per lb
15-28 bags, 41,95 cents per lb
29-50 bags, 39.45 cents per lb
1-9 bags, $16 per bag
10-20 bags, $11 per bag
21-100 bags, $9.25 per bag
S81.60 per drum
1-9	cylinders, $30 per cylinder
10-24 cylinders, $26 per cylinder
0-630	lb, 18.65 cents per lb
631-12,000 lb, 17.90 cents per lb
1 bag, $10.15.
2-20	bags, S8.90 per bag
21-100 bags, S7.65 per bag
1-40	bags, S2.85 per bag
41-200 bags, $2.23 per bag
1-9 bags, $36.80 per bag
10-19 bags, S34.80 per bag
varies, use $2.25 per lb
varies, use SO.30 per lb
92.35 cents per lb
73.80 cents per lb
Refer to section VIC for an example of the development of annual
operation and maintenance costs using the labor, power and supplies cost
curves and.the chemical cost table.
1. Unit Processes
Figures 34 through 75 are operation and maintenance cost curves for various
water treatment unit processes. Before using these cost curves, the estimator

should carefully review the following summaries of power requirements arid
chemical dosage rates or regeneration requirements used in developing the unit
process operation and maintenance cost curves. In addition, the preceding
introductory material should be reviewed for general considerations regarding
preparation of labor, power and supplies cost curves and Table 34, Water
Treatment Chemical Costs,
If local conditions dictate use of different design requirements, the
operation and maintenance cost curves must be revised accordingly,
a.	Mechanical Draft Aeration.. Operation and maintenance cost curves
developed for mechanical draft aeration include power and supplies, which are
presented on Figure 36. Power requirements are based on the blower motor
horsepower and 24 hour per day operation.	•	'
b.	Diffused. Aeration. Operation and maintenance cost, curves for
diffused aeration include power requirements and supplies, as shown on
Figure 37. Power requirements are based on the compressor motor horsepower
and 24 hour per day use. • •
c.	Activated Carbon Beds. Included in the operation and maintenance
cost curves for activated carbon beds are power, equipment supplies, and
enclosure supplies., These three cost curves are presented on Figure 38. An
activated carbon media replacement cost curve is presented on Figure 39. Power
costs are based on . the backwash pump and .surface 'wash pump, motor
horsepower requirements and their use for one hour each day. The media
replacement cost curve is based on shipment of spent carbon to a custom
regeneration facility. Assumed transport distance and regeneration interval are
1610 km (1000 miles), one-way, and 6 months, respectively.. Included in the
media replacement cost curve are freight, regeneration and replacement of
media lost during shipping and/or regeneration. Necessary labor was assumed
provided by the water treatment facility, therefore' no additional cost was
d.	Activated Alumina Columns. Operation and maintenance cost curves
for activated alumina include power, equipment supplies and enclosure supplies,
which are presented oh Figure 40. A regenerative chemical cost" curve is also

presented for activated alumina columns on Figure 41, Power requirements are
based on the total motor horsepower for surface wash pump, backwash pump,
chemical feed pumps, and chemical mixer. Use of the backwash and surface
wash pumps is estimated at one hour each day and the chemical feed pumps
and mixer are estimated for use once every six days for 2 hours. The
regenerative chemical cost curve includes cost for sodium hydroxide and
sulfuric acid. Available information indicates that activated alumina. material
must be replaced every 2 to 5 years.
¦ e. Rapid Mix. Rapid mix operation and maintenance cost curves
include power and equipment supplies and are shown on-Figure 42. Power
requirements are based on the flash mixer motor horsepower and 24 hour per
day operation.
f.	Flocculation. Operation and maintenance cost curves developed for
flocculation include power and supplies and are shown on .Figure 43. Power
requirements' are based on the turbine flocculator motor ; horsepower and
24 hour per .day use.
g.	Sedimentation, Operation and maintenance cost curves developed for
the -sedimentation, process include a cost curve for power and -one for supplies
as shown .on; - Figure 44. The power cost curve is based on the horsepower
requirement,of the sludge collector motor and 24 hour per day. operation.
i ih. Flocculator-CLarifier, Developed for the flocculator-clarifier are :
operation and maintenance cost curves for power and supplies. These two cost
curves.are.shown on,Figure 45. Power costs are based on sludge collector motor
¦horsepower, turbine flocculator motor horsepower, and - 24 hour per .day
i. Ion Exchange Softening. Ion exchange softening operation .and .
¦maintenance cost: curves include curves for power, equipment supplies and
enclosure: supplies, .which.are shown on Figure 46. A regenerative .chemical cost
curve is provided for ion exchange softening on Figure 47. Power requirements
are -.based on thentotal motor horsepower for backwash, pump and chemical
mixer. Use of this equipment is estimated at one hour per day. The regenerative
chemical cost ¦ curve is based on equipment manufacturer's stated salt require-

j. Pressure Filtration. Operation and maintenance cost curves for
pressure filtration include power, equipment supplies, and enclosure supplies
cost curves for surface loading rates of 120, 240 and 360 m^/m?/day (2, 4 and
6 gpm/ft^). Figures 48 and 49 include these nine cost curves. Power costs are
based on backwash pump motor horsepower, surface wash pump motor
horsepower and equipment use one hour each day,
k. Gravity Filtration. Gravity filtration operation and maintenance cost
curves include power, equipment supplies and enclosure supplies cost curves for
O	'J
surface loading rates of 120, 240 and 360 trr/nrr/day (2, 4 and 6'gpm/ft ).
These nine cost curves are presented on Figures 50 and 51'. Power costs are
based on motor horsepower requirements for backwash pump, surface wash
pump, and equipment use for one hour each day.
1. Demineralization. Operation and maintenance cost curves for de-
mineralization include power, equipment supplies, enclosure supplies, and
regenerative chemicals. These curves are shown on Figure 52 and Figure 53.
Power requirements are based on the total motor horsepower for
backwash pump, chemical feed pumps and on use of each of these pumps one
hour each day for systems less than 380m^/day (0.1 mgd) and three hours
each day for systems greater than 380m^/day (0.1 mgd). The regenerative-
chemical cost curve is based on costs for caustic soda and sulfuric acid'.;
m. Electrodialysis. Operation and maintenance cost curves developed
for the electrodialysis unit process include power, equipment supplies and
enclosure- supplies. Power and equipment supplies cost curves- are presented on
Figure-54. Power - costs are based on power requirements for the electrodialysis
process equipment, feed pump motor, brine recirculation pump- motor and
chemical cleaning equipment. Power costs are based on 3 kWh per m (11 kWh
per 1000 gal) and equipment supplies costs include membrane and cartridge
filter replacements plus cleaning chemicals. Figure 55 includes the enclosure
supplies cost curve.
n. Reverse Osmosis. Reverse osmosis operation and maintenance cost
curves include power, equipment supplies and enclosure supplies. Figure 56

includes the power and equipment supplies cost curves. Power costs are based
on 3 kWh perm3 (11 kWh per 1000gal) and equipment supplies costs include
• membrane and cartridge filter replacements along with necessary chemicals. The
enclosure supplies cost curve is presented on Figure 57.
o. Chemical Feed. Operation and maintenance cost curves for chemical
feed systems include power, equipment supplies and enclosure supplies for
various chemical dosages. Summarized in Table 35 are the chemical feed
systems and their appropriate cost curve figure numbers. .
Table 35
Chemical Feed System	Dosages (mg/1)	Figure Numbers
Powdered Activated Carbon	50 or less	58
Coagulant	50 or less	59
Hydrated Lime	50 or.less, 100 &	200 , 60, 61
Polymer	: 0.5, 1, 3 & 5	62, 63
Polyphosphate "	5 or less	64
Chlorine	5 or less & 10	65
Ozone	1.5, 5 & 10	" ' 66, 67
Calcium Hypochlorite	1.5, 5 & 10	68, 69
Sodium Hypochlorite	. 1.5, 5 & 10	70, 71
Sodium Hypochlorite :	1.5, .5 & 10 .	. . 72, .73
(on-site generation)	,,
Power costs are based on necessary feeders, agitators, mixers, and metering
pumps and 24 hour per day operation. In addition to the chemical feed costs
previously discussed, cost curves for ozone and sodium; hypochlorite (on-site
generation) include the following operation and maintenance costs: power for
chemical generation and supplies- fqr the: generating equipment and enclosure.
I	k

Ozone power requirements are based on 26 kYVh per kg (12 kWh per lb)
of ozone produced. Power requirements for on-site production of sodium
hypochlorite are based on lQkWh per kg (4.6 kWh per lb) of chlorine
produced. Ozone and sodium hypochlorite production is based on a flow rate
of 70 per cent of plant capacity. The salt requirement for sodium hypochlorite
production is 4.7 kg per kg (4.7 lb per lb) of chlorine produced.
2.	Laboratory Facilities
Laboratory costs depend on type and frequency of analyses and type and
condition of testing equipment. Laboratory operation and maintenance costs
should be determined for each local water treatment situation. Therefore, these
costs are not presented in this report,
3.	Waste Disposal Facilities
The operation and maintenance cost curve for lagoons is based on waste
solids removal by contract. This cost is related to the total solids produced
using an alum dosage of 30 mg/1 and a turbidity removal of 50 JTU. The
lagoon sludge removal cost curve is shown on Figure 74.
4.	Package Plants
Package plant operation and maintenance cost curves include power,
equipment supplies and enclosure supplies as shown on Figure 75, Power
requirements are based on the total'motor horsepower for the flash mixer,
mechanical flocculator, effluent, backwash and chemical feed pumps, and the
chemical mixers. Power costs include equipment use 24 hours per day.
5.	Upgrading Existing Facilities
Operation and maintenance cost curves corresponding to the various
upgrading methods described in section V have been discussed previously. Cost
curves are not presented for replacement of filter media, chemical change,

improvement of hydraulic conditions, operator training, monitoring, or control.
These are best determined for each water treatment situation. Cost curves for
tube settlers are not included as this upgrading method generally does not
create additional operation or maintenance costs.
Three examples have been prepared which illustrate use of the cost data in
this report. Examples No. 1 and 2 develop capital and operation and maintenance
costs for conventional facilities; Example No. 3 develops similar costs for a
package plant.. As Examples No. 2 and 3 are for facilities with equal capacity,
a comparison of costs for a conventional facility versus costs for a package plant
can be made.
1. Example No. 1
= The. following example is based on treatment of a surface water" for
turbidity: removal in a 3,000 m^/day (0.8 mgd) enclosed conventional plant
with, the following unit processes:
Rapid Mix . ¦ • - ;
Filtration-gravity with 240 m^/m^/day (4 gpm/ft?) rate
Coagulation Feed-alum-20 mg/1
Polymer Feed-dry 0.5 mg/1	/ -
Chlorine Feed—gas—5 mg/1 ...
Laboratory	j

a. Capital Cost — 3,000 m^/day (0.8 mgd) Conventional Facility.
Rapid Mix (Figure 9)
Flocculation (Figure 10)
Sedimentation (Figure 11)
Filtration—Process (Figure 15)
Filtration—Enclosure (Figure 15)
Coagulant Feed-Process (Figure 22)
Coagulant Feed—Enclosure (Figure 22)
Polymer Feed—Process (Figure 24)
Polymer Feed—Enclosure (Figure 24)
Chlorine'Feed—Process (Figure 26)
Chlorine Feed-Enclosure (Figure 26)
Lagoons (Figure 31)
Laboratory (Section IV, B, 2)
$ 21,000
An economic evaluation of proposed facilities should include a comparison
of either the present worth or the annual cost of the alternatives; It is common
practice in the water industry to use annual costs for judging alternatives. For
purposes of this report, a plant service life of 30 years and an interest rate of
8 per cent have been assumed. To determine the equivalent annual cost for
repayment of the capital cost, multiply the capital cost by the appropriate
capital recovery factor, as follows:
Annual Capital Cost = <	• . . .• -
Capital Recovery Factor (30 yrs @ 8%) .x Total'Capital Cost =
Annual Capital Cost = $47,480
listed in Table 36 are additional capital recovery factors for various interest
0.0883 x $534,500

Table 36 .
Capital Recovery Factor
1 '
1.060 00
1.080 00
1,100 00
0.545 44
0.560 77
0.576 19
0.591 70
0.374 11
0.388 03
0.402 11
0.416 35
0.288 59
0.301 92
0.315 47
0.329 23
0.237 40
0.250 46
0.263 80
0.277 41
0.203 36
0.216 32
0.229 61
0.243 23
0.179 14
0.192 07
0.205 41
0.219 12
0.161 04
0.174 01 .
0.187 44
0.201 30
0.147 02
0.160 08
0.173 64
0.187 68
0.135 87
0.149 03
0.162 75
0.176 98
. 0.126 79
0.140 08
0.153 96
0.168 42
0.119 28
0.132 70
0.146 76
0.161 44
0.112 96
0.126 52
0.140 78
0.155 68
0.107 58
0.121 30
0.135 75
0.150 87
0.102 96
0.116 83
0.131 47
0.146 82
0.098 95
0.112 98
0.127 82
0.143 39
0.095 44
0.109 63
.0.124 66
0.092 36
0.106 70
0.121 93
0.137 94
0.089 62
0.104 13
0.119 55
0.135 76
0.087 18
0.101 85
0.117 46
0.133 88
0.085 00
0.099 83
0.115 62
0.132 24
22 •
0.083 05
0.098 03
0.081 28
0.096 42
0.129 56
24 ¦
0.079 68
0.094 98
0.111 30
0.128 46
0.078 23
0.093 68
0.110 17
0.127 50
0.076 90
0.092 51
0.109 16
0.126 65
0.075 70
0.091 45
0.108 26
0.125 90
0.074 59
0.090 49
0.107 45
0.125 24
0.073 58
0.089 62
0.106 73
0.124 66
0.072 65
0.088 83
0,106 08
0.124 14
*E. L.
Grant and W, G. Ireson,
"Principles of Engineering
5th edition, Ronald
Press, New York, 1970.

VI-2 6

b. Annual Operation and Maintenance Cost — 3.000 m^/day (0.8 rtigd)
Conventional Facility.
Rapid Mix—Power (Figure 42)	$ 690
Rapid Mix-Supplies (Figure 42)	270
Flocculation—Power (Figure 43)	340
Flocculation-Supplies (Figure 43)	500
Sedimentation-Power (Figure 44)	430
¦ Sedimentation—Supplies (Figure 44)	340
Filtration-Power (Figure 50)	95
Filtration-Process Supplies (Figure 50)	, 380
Filtration—Enclosure Supplies (Figure 51)	305 <
' Coagulant Feed—Power & Process Supplies (Figure 59)	220 '
Coagulant Feed—Enclosure Supplies (Figure 59)	* 70
Polymer Feed—Process Supplies (Figure 62)	120
Polymer Feed—Power (Figure 63)	170
Polymer Feed-Enclosure Supplies (Figure 63)	70
Chlorine Feed—Power (Figure 65)	40
Chlorine Feed—Process Supplies (Figure 65)	75
Chlorine Feed-Enclosure Supplies (Figure 65)	70
Lagoon (Figure 74)	3,700
Chemicals (based on a flow of 70% of capacity)
. (Table 34)
Alum@Sll/bag	3,750.
Chlorine @ S26/cylinder	2,195
Polymer @ $2.25/lb.	1,900
Labor - Plant Type 3 (Figure 35)	„ 69,000
(For "Plant Type" description see page VI-16)		
Total	$84,730
Total Annual Cost =
Annual Capital Cost (pg VI-25) + Annual O&M Cost =
$47,480 + $84,730
Total Annual Cost = $132,210

Annual Cost per 1000 m^ (average flow = 70% of capacity)
S132,210 = S172 per 1000 m3
- (3) (365) (0.7)
Annual Cost per 1000 gal (average flow = 70% of capacity)
$132,210 - $0.65 per 1000 gal
(800) (365) (0.7)
2. Example No. 2
The following example is based on treatment of a surface water for
turbidity removal in a 1,100 m /day (0.3 mgd) enclosed conventional plant
with the following unit processes;
Rapid Mix
Filtration—gravity with 240 rrr/nn /day (4 gpm/ft') rate
Coagulant Feed—alum—20 mg/1
Polymer Feed—dry—0.5 mg/l
Chlorine Feed— gas—5 mg/1
a. Capital Cost - 1,100 m^/day (0.3 mgd) Conventional Facility.
Rapid Mix (Figure 9)
. $ 19,000
Flocculation* (Figure 10)
Sedimentation (Figure 11)
Filtration—Process (Figure 15)
Filtration—Enclosure (Figure 15)
Coagulant Feed—Process (Figure 22) -
Coagulant Feed—Enclosure (Figure 22)
Polymer Feed—Process (Figure 24)
Polymer Feed-Enclosure (Figure 24)

Chlorine Feed—Process (Figure 26)	7,000
Chlorine Feed—Enclosure (Figure 26)	3,700
Lagoons (Figure 31)	5,000
Laboratory (Section IV, B, 2)	7,000
Total	$454,500
Annual Capital Cost =
Capital Recovery Factor (30 yrs 8%) x Total Capital Cost =
O.088S3 x $454,500
Annual Capital Cost = $40,370
Refer to Example No. 1 for discussion of the method used for calculating
annual capital cost.
Refer to Table 36 for additional capital recovery factors.
b. Annual Operation and Maintenance Cost — 1,100 m^/day (0.3 mgd)
Conventional Facility.
Rapid Mix—Power (Figure 42)	$' 420
Rapid Mix-Supplies (Figure 42)	240
Flocculation—Power (Figure 43) ' 300
Flocculation—Supplies (Figure 43)	- 450
Sedimentation—Power (Figure 44)	370
Sedimentation—Supplies (Figure 44)	300
Filtration—Power (Figure 50)	80
Filtration—Process Supplies (Figure 50)	300
Filtration—Enclosure Supplies (Figure 51)	170
Coagulant Feed—Power & Process Supplies (Figure 59)	220
Coagulant Feed—Enclosure Supplies (Figure 59)	70
Polymer Feed—Process Supplies (Figure 62)	120
Polymer Feed—Power (Figure 63) ' "	170
Polymer Feed—Enclosure Supplies (Figure 63)	70

Chlorine Feed—Power (Figure 65)
Chlorine Feed—Process Supplies (Figure 65)
Chlorine Feed—Enclosure Supplies (Figure 65)
Lagoon (Figure 74)
Chemicals based on a flow of 70% of capacity)
(Table 34)
Alum @ $ 11 /bag
Chlorine @ S30/cylinder
Polymer @ $2.25/lb
Labor-Plant Type 3 (Figure 35)
(For "Plant Type" description see page VI-16)
Total Annual Cost =
Annual Capital Cost (pg VI-29) + Annual O&M Cost =
540,370 + 570,355
Total Annual Cost = $110,725
Annual Cost per 1000 m^ (average flow = 70% of capacity)
SI 10,725 = S394 per 1000 m3
(1.1) (365) (0.7)
Annual Cost per 1000 gal (average flow = 70% of capacity)
$110,725	= SI.44.per 1000 gal
(300) (365) (0.7)

3. Example No. 3
The following example is based on treatment of a surface water for
turbidity removal in a 1,100 m^/day (0.3 mgd) enclosed package plant with the
following unit processes:
Rapid Mix
F iltr at ion—gravity
Coagulant Feed—alum—20 irtg/1
Polymer Feed—dry—0.5 mg/1
Chlorine Feed—gas—5 mg/1
a. Capital Cost - 1,100 m^/day (0.3 mgd) Package Plant. .
Package Plant—Process (Figure 32)	$160,000
Package Plant—Enclosure (Figure 32)	37,000
Lagoons (Figure 31)	5.000
Laboratory (Section IV, B, 2)	• 7,000
Total	$209,000
Annual Capital Cost =
Capital Recovery Factor (30 yrs (§ 8%) x Total Capital Cost =
0.08883 x $209,000
Annual Capital Cost = $18,560
Refer to Example No. 1 for a discussion of the method used for
calculating annual capital cost. Refer to Table 36 for additional capital recovery

b. Annual Operation and Maintenance Cost — 1,100 m /day (0.3 mgd)
Package Plant.
Package Plant—Process (Figure 75)	$ 680
Package Plant—Power (Figure 75)	¦ 1,600
- Package Plant-Enclosure (Figure 75)	600
Lagoon (Figure 74)	1,800
Chemicals (based on a flow of 70% of capacity)
(Table 34)
Alum @$11 /bag	1,410
Chlorine @ $30/cylinder	960
Polymer @ $2.25/lb. .	720
Labor—Plant Type 2 (Figure 34)	5,200
(For "Plant Type" description see page VI-16)
Total . . ¦	. $12,970
Total Annual Cost =
Annual Capital Cost (pg VI-31) + Annual O&M Cost =
$18,560 + $12,970
Total Annual Cost = $31,530
Annual Cost per 1000 m^ (average flow = 70% of capacity)
$31,530	=$112 per 1000 m?
(1.1) (365) (0.7)
Annual Cost per 1000 gal (average flow = 70% of capacity)
$31,530 = $0.41 per 1000 gal
(300) (365) (0.7)

Table 37
	Annual Cost	
S per 1,000 n^~~ " $ per 1,000 gal
Example No. 1
3,000 m^/day (0.8 mgd)
Conventional Facility	172	0.65
Example No. 2
1,100 nr*/day (0.3 mgd)
Conventional Facility	394	1.44
Example No. 3
1,100 m^/day (0.3 mgd)
Package Plant	112	0.41


1000	2	3	4	56789 10,000
I	1_	)	j	1	1	1	(	1	1	f—t—)_|	1	1
0.3	05	1,0	1.5	2.0
" I •' | ¦	1	1	-—i		1_|	—,	,	1	1
250	500 1000 • -	,5000	10,000

100	2 3 456789 1000	2 3 4 5678910,000
I ,000,000
4,5 6 7 8 9 1000	2
4 5 6 7 8 910,000
H	I—I—I-

-I	h
0.05	0.1	0.5
" 1.0
1.5 2.0
H	h t- | 4 H )¦ I
250 500 1000
5000 10,000
, 4

!0,000	' •
1000	2	3	4	5 6 78 9 10,000
I	,—	1	-|	1	1	y	i—|—h—i—I—t—t	1			'
0.3	0.5	i.O	1.5	2.0
1	(	1	)	(	1	1	|-	(	1	1	1	1	:	J
250	500 1000	5000	10,000

g 30,000
20,000 '
. i.0,000
1000	2	3	4	567 89 10,000
- • •• ; I - • t • :	i-' 		[-			" 	1- - • -I	1—t	 	i' 	t i	—\	¦	1
0.3	0.5	l.O	1.5	2.0
L-1—f—"	' ' 1 ', * 	—-i	I	^—*'	" 1	1
250	500 1000	5000	10,000 '
•	FENCING	' ¦¦ ¦'

o 300,000
100,000	¦ • .	.
1000	2	3	4	5 6789 10,000
1	1		1	|i	—|	1	1	1—|—h-+-	—|	1
0.3	0.5	1-0	1.5	2.0
I	)	,	1	,	,	,	1	| | 4.1	1	:	>.
250	500 1000	5000	10,000

g 300,000
1000	2	3	4	5 6789 10,000
I	1	1 . " i	1-	\	1	1	1	1	1—I	h-1	¦	1	1
0.3	0.5	1.0	1.5	2.0
1	1_	:	1	1	,	1	1—j—f—,—,—,	1	1
250	500 1000	5000	10,000
r.	.	FIGURE 12

100	2 3 4.5 6 7 8 9 1000'	2 3 4 5 6 7 8 910,000
I	—|—	,	1	1	1	,—,—^^	1
0.05	0.1	0.5	1.0 ' " 1.5 2.0
I	250 500 1000 ' s'o'oo ' lOJDOO 1
• **	FIGURE 13

1000	2	3	4	5 6789 10,000
I	1	1	1	1	1	1_	(	1	1	,		!	j	1	1
0 3	0.5	10	1.5	2.0
I—i	<	1	,	,	,—|—i , | i ' i	:	1
250	500 1000	5000	10,000

-U> 100,000
360 m
2	3	4	5
8 9 10,000
-t	(•	H
-I	H
—I	1	
500 1000
-I	i	1—I—"—¦	1	
5000	10,000
« valves, piping a controls

100	2 3 4 5 6 7 8 9 1000	2 3 4 5 6 7 8 910,000
! ,000,000'
4 5 6 7 8 9 1000	2	3 4 5678910,000
o.i	0:5
-f	1—
1.5 2.0
-H	1	1	—I	1	1	! I I HI l-l
50 100 250 500 1000 . 5000 10,'

- I
3- 4 5 6 7 8 91000	2 3 4 5 6 7 8 910000
4——I	1 . 1 |
0.1	0.5
_l—	1—(—i-H"

IS 2.0

H—I	I	I- <	t	I	I-
100 250 500 ©00
5000 10,000

4 5 6 7 8 9 1000	2
-4	1	1-	f	(	|	

4 5 6 7 6 910,000
0.1	0.5 "
—i	—
1,5 2.0

—f	j	1-
50 100 250 500 1000
50^00 IO'POO

I,000|0b	2	5 6 "78'9 1000 ~~Z~ " 3 "~4 5 6 7 8 910,000
H—I I	t I	;	1	1	1	1—=—I	1—t-f-
0.05	0.1	0.5	1.0 1.5 2.0
H	i	1	1	1	1— 'MM
	-	oc
25	50 100 250 500 1000	5000 10,000

< 20mg/l
&0 m

C 20mg/l
1000	2	3	4	5 6 7 8, .9 10,000
-»	1	i	1	1—I—I-
0.3	0,5 -	1.0	1.5 • 2,0

o 10,000
1000 •
1000	2	3	4 -56789 10,000
'	1	1	1	1	1	1	1—)	1—i—i—i—|	H	1
0,3	0.5	t.O	"1.5	2.0 '
I	1	1	1	1	1	1	1	1—|—i—i	1	1
250	500 1000	5000	10,000


3 mg/l
I mg/l
iOOO	2	3	4	56789 10,000
	,	,	1	j	,—,—,—H
-i	1	1—i—t—i—t-
250	500 1000	5000	10,000
0.3	0,5	1.0	1.5	2.0

<5 mg/l
g 3,000
< 5mg/l
1000	2	5	4	56789 10,000
i	,	1	1	,	)	1	,—|	1—,—,—,—1			1	1
0.3	0.5	1.0	1.5	2.0
I	1	:	1	)	1	1	1	)	1—I	1	1	1	1
250	5 00 1000	5000	10,000



< 5mg/l

1000	2	3	4	56789 lOpOO
I	1	1	1	1	1	1	t	f t	1—i—i—|	1	1
0.3	0.5	i.O	1.5	2,0
	1	1	,	,	,—|—,—i—(—i—	
250	500 1000	5000	10,000

S 00,000
2	3	4	5
H	h

0.5	1.0
500 1000
H	1	1 »
£ 3 He>T£
9 10,000

to 0,000
g 10,000
<	i
I 5mg/l
5 mg/>
1000	2	3	4	56789 10,000
I	1	1	1	1	1	(	1	1	1	1—i—i—|	1	1
0.3	0.5	1.0	1.5	2-0
-t-	1	1	1	1	1	1	H
250	500 1000	5000	10,000

1.5 mg/i
1000	2	3	4	56789 10,000
I	)	1	1	1	(	1	,	j	1	,—,—,_|	1	1
0.3	0.5	1.0	1.5	2.0
J	j__	1	1	1	1	1	1	f—|—i	1	1
250	500 1000	5000	10,000
SIZES IS $3700.

1.5 mg/l
1000	2	3	4	5 6 7 8 9 10,000
!¦—	t —>¦ -	 —I	1	1	1	}	f	I—I	1—|	1 ¦ ¦ - J
0.3	0.5	10	1.5	2 0
I	,	1		1	1	,	1	,—|—|—|	1	1
250	500 1000	5000	10,000

5,000:- - -
1,000-. -	. -	-	¦ -	-- 	-J 	
100	2	3456789 1000	2	3 4 5 6 7 8 910,000
J			1	1	)- f j- |	1	1	i	i	1	1—t-t-|	1	1	I
0.05	0.1	0.5	1.0 1.5 2.0
-1	1	1	1	1	1—f-
{44-M-	[¦¦¦¦
300 IOC
25	50 100 250 500 1000	5000 10,000


J	1	i—|—1—S—|	i	1	\	1—-t H	-» I-)—¦	—t-	|—
0.05 0 1 0.5	1.0 1,5 2.0
I	1	1	1	1	1	1	1—i h|h h I	
25 50 100 250 500 1000	5000 10,000



4 5 6 7 8 9 1000	2 3
4 5 6 7 8 910,000
	I		I	I	I	|	
0.1	0.5

1.5 2.0
50 100 £50 500 1000
5000 10000

2	3	4	5
8 9 I0P00
-t	y—
-~		<—»-
-I	1	1	1	»	h-
5000	10,000
* 31

10,000 r-
5,000 l-
3 4 5 6 7 8 9 1000	2	3 4 5 6 7 8 910,000
-i	1—f—I—(—j	1	1	(	1	1	1—t—t-
0.05	0,1	0!5
-•	1-
1,5 2.0
50 100 250 500 1000
—1, 1	| | | i	1
5000 io;<
- 32


500 H-
IOi —
I 1 I
4 5 6 7 8 9 1000	2 3
4 5 6 7 8 910,000
	1	1	1	1_
0,1	0.5
—I	1—
1.5 iO
	,	1 I (	M (	I
50v0 10
250 500 1000
PAGE 3EL- 16.

100	2	3456789 1000	2	3 45678910,000
I	1	1—i—i—(_|	— - I	1	1	i	1—i—i—H	1	1	1
0.05	0.1	0.5	1.0 1.5 2.0
_i	,	1	1	(—i Mini)
25	50 100 250 500 1000	5000 10,000

I ,000r
50- -
1 °(00	2 3 456789 1000	2 3 4 5 6 7 8 910,000
J	1	1	1 | i |	1	1	1	1	1	1	t-H	1	1	1
' 0,05	0,1	015	1.0 1.5 2.0
H	1	1	<	1	1	1—I I H	< I
25	50 100 250 500 1000	5000 lOiOOO
PAGE "21- 16.

,000|QQ 	2 3~ " ' 4 "" 5 6 " 1 8 91*000 "" "" " 2 			3 ' " 4 " 5 6 T 8 310,000
J	1	1	1 [ >	|	f.	1	1	1	1	1	>—H	1			1	1
0.05	0.1	0,5	1,0 1.5 2.0
_j	f	j	j	1	(	1—t,. I j ) „j,
...				_lloo
25	50 100 250 500 1000	5000 10,000

1000	2	3	4	56789 10,000
1000	2	3	4	56789 10,000
1	1	,	)—:	,	1	)	1—|	1—,—,—hH	(	—I
0.3	0.5	1.0	1.5	2.0
"I	1	1	1	1	1	f-H	H
250	500 1000	5000	10,000
PAGE "21- 16.

300 <
3	4	5 6 7 8 9 10,000
-I	1	1	1-
_l	1—|—|—(_
0.5 .	1.0
-I	1	h
-1—1—I	i	h
250	500 • 1000	5000	10,000
PAGE 21-16.

1000	2	3	'4	5 6 7 8 9 10,000
'	1	1	1	1	1	1	1	1	1	f—i—i—|	1	1
0.3	0.5	1.0	1.5	2.0
-i	1	1	1—I—•—f-
250	500 1000	5000	10,000

100	2	3456789 1000	2	3 456789 lOpOO
I	(	1	tiij	1	1	1	1	1	1—i—H	1	1	1
0.05	0.1	0.5	1.0 1.5 2.0
'	i	' JJJJ ' U-
25	50 100 250 500 1000	^o'oo1 io'poo
PAGE m- 16.


100'	2	3 456789 1000	2	3 4 5 6 7 8 910,000
—i—i—i i i |	1	1	1—|—i—i—i—H	1	1	1
0.05	0.1	015	1,0 1.5 2.0
_i	1	1	1	1—[Iiiii
25	50 100 250 500 1000	5ofe 10',000

-j—~i— T- —;—\—r
-!	1

	)—-1	H
500 1000
PAGE 31- 16.

2	3	4	5
7 8 9 10,000
-i	1-
-t	1	I	H
0.5	1.0
^	1-
-i—I—•	h
500 1000	5000
PAGE m-16.

g 100
3	4	5
e 9 10,000
	1	1	I	!	(	(.	1	1	(-
0,5	1.0

-i	-t-
500 1000
5000	I0,b00
PAGE HL~ 16.

2	3	4	5
6 7 8 9 10,000
-i	h
-f—|	*—i—t—M-
H	1	»-
-I	1	H
250	500 1000	5000	10,000
PAGE -32-16.

4 5 6 7 8 9 1000	2	3
4 5 6 7 8 9 10,000
1 I I I I
I ' 1 ' 'J
0.1	0:5
1.5 2.0
¦I 1 i-m	I
OOO 10
250 500 1000
PAGE m - 16.

4 5 6 7 8 9 1000	2 3 4 5 6 7 8 910,000
_i	1—t—i—(—|	
0.05	0.1 ¦	0.5
H	1	1—I—M4-
1.5 2.0

-H	H
H	1	1 | I I I 1 I
50 100 250 500 1000
5000 iOpOO

£ 50,000
100	2 3 4 5 6 7 0 9 1000	2 3 4 5 6 7 8 910,000
1	I	i—I—1—H	1	1	1	1	1—1—H	1	1	1
0.05	0.1	0.5	1.0 1.5 2.0
I	,	1	1	,	,	,	,	1—| | | | I I 1	L
25	50 100 250 500 1000	500 0 10,000
PAGE 3ZE- 16,

4 5 6 7 8 9 1000	2 3
4 5 6 7 8 910,000
H	1	1	1	J-
	1	;	1	1	
o.i	o's
50 100 250 500 1000
^	1—I [ I I I I
1,5 2,0
5000 10 000
PACE HL- 16.
operation and maintenance COST
- SI

100	2 3 4 5 6 7 8 9 1000	2 3 4 5678910,000
1	1-—I—I—l—H	1	1	1	*	1	'—1—|-H	1	1	'
0.05	O.i	0.5	1.0 1.5 2.0
I	,	,	1	1	(_—i	1	1—iiiiiii	1
25	50 100 250 500 1000	5000 10/300
PAGE 16.

3 4 5 6 7 8 9 1000	2
_|	1—1—I—|	1	1	1	1	h-
0.1	0.5
5 6 7 8 910,000
1.5 2.0
50 . 100 250 500 1000
i i h '' ' I
50*00 10
PAGE "2T -16,


u 30»
<1 50 mg/I

< 50mg/l

< 50mg/l
1000	2	3	4	5 6789 10,000
^	< SO mg/l
iOOO	2	3	4	5 678 9 IOPOO
-H	f	1	1	*	1-
0,3	0.5	1.0	1.5	2.0
	1	,	,	,	1	,—|—,—H
250	500 1000	5000.	10,000
PAGE "21-16
operation and maintenance cost
55	.. ¦

<50 rng/l
1000	2	- 3	456789 10,000
1	1	1	1-	1	1	1	1	1	1	1—i—i—|	1	1
0.3	0.5	1.0	1.5 • 2.0
~i	1	1	1	1	I	1	1	H
250	500 1000	5000	10,000

« 300
2	3	4	5
7 0 9 10,000
—t	1	1	1	1	1	H	1	(	M—
0.5	1.0	1.5
0 3

500 1000
_l	1	1	1—(—(—|	|_

g 300
200 <
0,5 ma/l
2	3	4	5
	1	1	1	1—
-I	1—I—(-
0.5	1.0
500 1000
7 8 9 10,000
PAGE 3ZX - 16.

*¦» 0.5mg/l
1000	2	3	4	5 6789 10,000
1	1		1	1	i	(	1	(	1	1—i—i—j	1	1
0,3	0.5	10	1.5	2.0
1	1	1—	1	:—i	1	1	1	1—i—i—i	f—;	1
250	500 1000	5000	10,000
53	FIGURE 63

C 5 mg/I
< 5 mq/l
< 5 mg/I
10	,	-
1000	2	3	4	56789 10,000
—	i	1—:	1	1—	I	1		1	1	1	1	1	-	1	-
0,3	0.5	1.0	1.5	2.0
—|	h-r	H-—¦	:—' -¦ I—(-	1	1	1	I	1—t	' 			——	
250	500 1000	5000	10,000
PAGE ~3X - 16.

10	.
1000	2 .	3	4	56789 10,000
0.3,	0.5	10	1.5	2.0
-f	1	1	1	1	1	1	1	1	1-7	+
250	500 1000	5000	10,000

50,000 •
100	•	-
1000	2	3	456 7 89 10,000
H	1	1	1	H
0,3	0,5	1.0	1.5	2.0
I	1—i » i	f	
>00	10,000
250	500 1000	5000

10	-
1000	2	3	4	5 6 7 8 9 10,000
1	1	1	1	1	1	1	1	1,	1	,—|—i—|	1	1
0.3	0.5	1.0	1.5	ZjO
'	1	1	1	1	1	1	1	1	1	I	1	1	=	1
250	500 1000	5000	10,000
PAGE HE -16.
- £3	FIGURE 6?

10	¦ .	. .
1000	2	3	4	5678 9 10,000
I	1	1	:	1	-i	1	H	1	1	1	1	1	1	(	1	1
0.3	0.5	1.0	1.5	2.0
I	1	)	1-	1	!	1	1	1	1	1	1	1	1
250	500 1000	5000	10,000

o 100"
2.	3	4	5
H	1—+-
8 9 10,000
	1	(__i—1_

500 1000
5000	10,000

CO __
o 30
1000	2	3	4	56789 10,000
I	!	f	1	1	1	1	1	1	1	1	1	1—|	1	1
0,3	0.5	1,0	1.5	2.0
'—l	1	1	1	(	1—f——i—t—I	1
250	500 1000	5000	10,000
IS $70 FOR 10 mg/l, 5mg/l a l,5mg/l


5 mg/l
1000	2	3	4	5 6 T 8 9 10,000
2	3	4	5
7 6 9 IOPOO
H	!	1	I	1	1-
0.5	1.0
	1	,—|—,	1		
5000	10,000
500 1000


2	3	4	5
3 4 5 6 7 8 9 1000	2 3 4 5 6 7 8 9(0,000
H	1-

-4	H
H	1	h-+-
0.1	0,5
1,0 1.5 2.0

-4	|_
I | ] I I
50 100 250 500 1000
5000 10000

10,000"~ • - 		~	—
5,000		 - - * •
; power-
l00|00	2	3 4 5 6 7 8 9 1000	2	3 4 5 6 7 8 910,000
J			1	1 | ) |	1	1	1	1	1	1—H-+-J	1	1	1
0.05	0.1	0,5	1.0 1.5 2.0
-t	1-
¦4	1	!—I I 1 II 1 1
tooo 5obo io;c
25	50 100 250 500 1000	50*00 I0;000
PAGE 3ZT- 16.
71	FIGURE 75




National Interim Primary Drinking
Water Regulation,

Title 40—Protection of Environment
'[FRL 464-7]
, On March'14, 1975, the Environmental
Protection Agency (EPA) proposed Na-
tional Interim Primary Drinking Water
Regulations pursuant to sections 1412,
•1414, 1418, and 1450'of the Public Health
Service Act ("the Act"), as' amended by
the Safe Drinking Water Act ("3DWA,"
Pub. L, 93-523), 40'PR 11900. EPA held
public hearings on the proposed regula-
tions in Boston, Chicago, San Francisco,
and Washington during the month of
April. Several thousand pages of com-
ments on the proposed regulations were
received and evaluated. In addition, the
Agency has received comments and in-
formation on the proposed regulations
from the National Drinking Water Ad-
visory Council, the Secretary of Health,
Education, and Welfare, and from num-
erous others during meetings with repre-
sentatives of State agencies, public In-
terest groups and others.
The regulations deal only with the
basic legal requirements. ' Descriptive
material will , be provided in a guidance
manual, for use by public water systems
end the States, -
The purpose of this preamble to the
final regulations is to summarize the most
significant changes made in the proposed
regulations as a result of comments re-
ceived and the further consideration of
available information. A more detailed
discussion of the comments and of
changes in the proposed regulations Is
attached as Appendix A.
Water Systems Covehed
The Safe Drinking Water Act applies
to each "public water system," which is
defined in Section 1401(45 of the Act as
"a system for the provision to the public
of piped water for human consumption,
if such system has at least fifteen service
connections or regularly serves at least
twenty-five individuals." Privately owned
as well as publicly owned systems are
covered. Service "to the public" is inter-
preted by .JSP A to include factories and
private housing developments. (See. gen-
erally, House Report, pp. 16-17.)
The definition of "public water sys-
tem". proposed in the Interim Primary
Drinking. Water Regulations sought to
explain the meaning of the statutory
reference to "regular" service. It was
proposed to interpret tills term as Includ-
ing service for as much as three months
during the year. Because the proposed
definition' would have excluded many
large campgrounds, lodges, and other
public accommodations which serve
large numbers of tourists but which are
open for slightly less than three months
each year,' the definition in the final ver-
sion covers systems serving an average of
at least twenty-five Individuals at least
60 days out of the year. The use of a
minimum number of days rather than
months also makes clear that a system
may qualify aa a public water system
even Is not open every day during a
given month.
.Once "public water system" has been
defined, it is necessary to define the two
major types of public water systems—
those serving residents and those serv-
ing transients or intermittent users. The
possible health effects of a contaminant
in drinking water in many cases are quite
different for a person drinking the water
¦ for a Ion g period of time than for a per-
son drinking the water only briefly or In-
termittently. Different regulatory con-
siderations may. in some cases apply to
systems which serve residents as opposed
to systems which serve transients or In-
termittent users. Accordingly, § 141.2(e)
makes' clear that all "public water sys-
tems" fall within either the category of
"community water systems" or the cate-
gory of "non-community water systems."
To make clear which regulatory require-
ments apply to which type of system, the
category covered is specifically Indicated
throughout the regulations.
The proposed regulations defined a
"community water system" as "a public
water system which serves a population
of which 70 percent or greater are resi-
dents." Reliance in the proposed defini-
tion on the percentage of water system
users who are" residents would result In
treating some -fairly large resort com-
munities with many year-round residents
as non-community systems. Therefore,
the definition of "community water sys-
tem" has been changed to cover any sys-
tem which serves at least 15 service con-
nections used by year-round residents or
serves at least 25 year-round residents.
Small Community Water Systems
.Many community water systems in the
country are quite small. Since it is the
intention of the Act to provide basically
the same level of health protection to
residents of small communities as to
residents of large cities, and since a num-
ber of advanced water treatment tech-
niques are made' feasible only by eco-
nomies of scale, the cost of compliance
with the requirements of the Act may
pose a serious problem for many small
communities. The ¦ regulations seek to
recognize the financial problems of small
communities by requiring more realistic
monitoring for systems serving fewer
than 1,000. persons. Variances and ex-
emptions authorized by the Act can also
assist hi dealing with economic problems
of small community systems in appropri-
ate cases, at least" temporarily. EPA will
provide technical -'assistance on effective
treatment techniques which can be used
by small systems.
These methods, of dealing with the fi-
nancial problems of some small com-
munity systems may not be sufficient to
specific Instances to make - compliance
with all applicable regulatory require-
ments feasible. EPA Is commencing a
study of potential problems faced by
small community systems in meeting ap-
plicable requirements under the Act and
these regulations, and, if necessary, will
make additional adjustments in the In-
terim Primary Drinking Water Regula-
tions prior to their effective date.
Non-Community Systems
"Non-community systems" are basic-
ally those systems which serve transients.
They include hotels, motels, restaurants,
o&mpgTounds, service stations, and other
public-accommodations which have their
own water system and which have at
least 15 service connections, or serve
water to & daily average of at least 25
persona. Some schools, factories and
churches are also Included In this cate-
gory. It is conservatively estimated that
there are over 200,000 non-community
water systems in the country. However, it
should be recognized that while their
number is large, they normally are not
the principal source of water' for the
people they serve. •
The regulations as proposed would
have applied all maximum contaminant
levels to non-community systems as,well
as to community systems; This approach
failed to take into account the fact that
the proposed maximum. contaminant
levels for organic chemicals and most in-
organic chemicals were based on the
potential health effects of long-term ex-
posure. Those levels are not necessary
to protect transients or intermittent
users. Therefore, the final regulations
provide. that maximum contaminant
levels' for organic chemicals, and for In-
organic chemicals other than nitrates,
are .not applicable'to non-community
systems. An exception was'made for ni-
trates because they can have an adverse
health effect on susceptible infants In a
short period of time. '
Even without monitoring for organic
chemicals or most inorganic chemicals,
in the initial stages of implementation
of the drinking water regulations, mon-
itoring results from tens of thousands of
non-community systems could over-
whelm laboratory capabilities and other
resources. This could delay effective im-
plementation of the regulations with re-
spect to the community systems which
provide the water which Americans
drink every day. To avoid this result,
non-community systems will be given
two years after the effective date of the
regulations to commence' monitoring. In
the meantime, non-community systems
which already monitor their water are
encouraged to continue to do so. and the
States are encouraged, to take appropri-
ate measures' to test or require monitor-
ing for non-community systems that
serve large numbers of people.
Of course; non-community systems
which pose a threat to health should be
dealt with as quickly as possible. Hie
maximum contaminant levels applicable
to. non-community water systems there-
fore wfll take effect 18 months after pro-
mulgation, at the same time as levels ap-
plicable to community systems. Inspec-
tion and enforcement authority will ap-
ply to non-community, systems at the
same time as to community systems.
Sanitary Surveys
EPA encourages the States to conduct
sanitary surveys on a systematic basis.

These on-site inspections of water sys-
tems are more effective in assuring safe
water to the public than individual teste
taken in the absence of sanitary surveys.
The regulations provide that monitor-
ing frequencies for colifonn bacteria can
be changed by the entity with primary
enforcement responsibility for an .Indi-
vidual non-community system, and In
certain circumstances for an individual
community system, based on the results
of a sanitary survey, •
. Maximum Contaminant Levels
Numerous-comments were received by
EPA on the substances selected for the
establishment of maximum contaminant
levels and on the levels chosen. Congress
anticipated that, the initial Interim Pri-
mary Drinking Water Regulations would
be based on the Public Health Service
Standards of 1882, and this Congres-
sional Intent has been followed. Com-
ments received on the various levels did
not contain new data sufficient to re-
quire the establishment of levels differ-
ent from those contained in the Public
Health Service Standards,
Water Consumption
The maximum contaminant levels are
based, directly or Indirectly, on an as-
sumed consumption of two liters of water
per day. The same assumption was used
in the 1962 Standards. This assumption
has been challenged because of Instances
where much higher water consumption
rates occur. RPA's Justification for using
the two-liter figure is that it already
represents an above average water or
water-based fluid intake. Moreover, while
the factor of safety may be somewhat re-
duced- when greater quantities of water
are ingested, the maximum contaminant
levels based on the two-liter figure pro-
vide substantial protection to virtually
all consumers. If, as has been suggested,
'a water consumption rate of eight liters
per day is used as the basis for maxi-
mum contaminant level, all of the pro-
posed MCL's would have to be divided by
four, greatly increasing the monitoring
difficulties, and in some cases challeng-
ing the sensitivity of accepted analytical
procedures. It could be expected, in such
a case, that the maximum contaminant
levels would be exceeded to a significant
degree, and that specialized treatment
techniques would be required to order
that the contaminant levels would be re-
duced. The economic Impact of a move
In this direction would be enormous. It
is not technically or economically feasi-
ble to base maximum contaminant levels
on unusually high consumption rates.
•'Safety Factors
A question was raised about the fact
that different safety factors are con-
tained in various maximum contaminant
levels. The levels are not intended to
have a uniform safety factor, at least
partly because the knowledge of and the
nature of the health risks of the various
contaminants vary widely. The levels set
are the result of experience, evaluation
of the available data, and professional
judgment. Hiey have withstood the test
of time and of professional review. They
are being subjected to further review by
the National Academy of Sciences in con-
nection with development of data for the
Revised Primary Drinking Water Regu-
MCL's based on Temperature
A question was also, raised as to
whether ranges of maximum contami-
nant levels should be established oil the
basis of the climate In the area served
by the public water system, as was done
with fluoride. EPA believes that the use
of a temperature scale for fluoride is
more appropriate than for other chemi-
cal# because of the studies available on
the fluoride-temperature relationship
and because there is a small margin with
fluoride between beneficial levels and
.levels that cause adverse health effects.
. MCL's Deleted
Three proposed maximum contami-
nant levels have been eliminated in the
final regulations because they are not
Justified by the available data. One of
these is carbon chloroform extract
i.CCE), which is discussed separately
below. The others are-the proposed levels
for the standard bacterial plate count
and cyanide. In the case of the plate
count, it is believed that the colifonn
limits contained in the' regulations, com-
bined with the turbidity maximum con-
taminant level, adequately deal with
bacterial contamination. However, EPA
continues to believe that the standard
plate count is a" valid indicator of
bacteriological quality of drinking water,
and recommends that it be used in ap-
propriate cases in conjunction with the
coliform tests as an operational tool.
The proposed maximum contaminant
level for cyanide was eliminated because
the possibility of cyanide contamination
can be effectively addressed only by the
use of emergency action, such as under
Section 1431 of the Act. EPA's 1869 Com-
munity Water Supply • Study did not
reveal a single instance In which cyanide
was present in a water system at a level
greater than one-thousandth of the level
at which cyanide Is toxic to humans.
Available data indicate that cyanide
will be present in water systems at toxic
levels only in the event of an accident,
such as a spill from a barge collision.
Maximum contaminant levels are not
the appropriate vehicle for dealing with
such rare, accidental contamination.
Heptachor, heptachlor epoxide
and chlordane have also been removed
from the list of maximum cfintaminant
levels at least temporarily in view of the
pending cancellation and suspension
proceedings under the Federal Insecti-
cide, Fungicide and Rodentlclde Act in-
volving those pesticides. When the re-
sults of these proceedings are available,
EPA will again consider whether maxi-
mum contaminant levels should be es-
tablished for those three pesticides.
Sodium and Sulfates
A number of comments were received
on the potential health effects of sodium
and sulfates. The National Drinking
Water Advisory Council has recom-
mended that consideration be given to
the monitoring of these constituents, but
has not recommended the adoption of
maximum contaminant levels because
available data do not support the adop-
tion of any -specific levels. EPA has re-
quested the National Academy of Sci-
ences to include sodium and, sulfates
among the contaminants to be studied
by NAS, and to include information on
the health effects of sodium and sulfates
in the report to be made by NAS in
December 1878.
Since a number of persons suffer from
diseases which are influenced by dietary
sodium intake and since there are others
who wish to restrict their sodium in-
take, It is desirable that the sodium con-
tent of drinking water be known. Those
affected can, bv knowing the sodium con-
centration In their drinking water, make
adjustments-to their diets or, ta extreme
c&aes, seek alternative sources of water
to be used for drinking and food prepara-
tion/ It is recommended that the States
institute programs for regular monitor-
ing of the sodium content of drinking
water served to the public, and for in-
forming phvsicians and consumers of the
sodium concentration in drinking water,
A relatively high concentration of sul-
fate in drinking water .has little or no
known laxative effect on regular users of
the watef, but transients using such
water sometimes experience a laxative
effect. It Is recommended that the States
institute monitoring programs for sul-
fates, and that transients be notified if
the sulfate content of the water is high.
Such notification should include an as-
sessment of the possible physiological
effects of consumption of the water.
FCB's and Asbestos
An interagency comment expressed
concern for asbestos and PCB's in the
environment and noted the need for at
least a monitoring requirement, if not
for MCL's, for these contaminants. EPA
is also concerned, but for the moment
lacks sufficient evidence regarding ana-
lytical methods, health effects, or occur-
rence in the environment to establish
MCL's.' The Agency Is conducting re-
search and cooperating In research proj-
ects to develop criteria for establishing
needed limits,as quickly as possible. A
monitoring study on a number of organic
chemical contaminants, Including PCB's,
for which MCL's are not being estab-
lished at this time, will be contained in
an organic chemical monitoring regula-
tion that is being promulgated with these
regulations. Regarding asbestos, HEW
and EPA are sponsoring a number of
studies this year at an approximate cost
of $16 million to establish health effect";,
anayltic&l methods and occurrence.
Point op Measurement
Other .comments on maximum con-
taminant levels focused on the proposed
requirement that such levels be tested
at the consumer's tap. Concern was ex-
pressed over the inability of the public
water system to control potential sources

ol contaminants which are under the
control of the consumer.
Hie promulgated definition of "maxi-
mum contaminant level," 5 141.2(d), re-
tain! the requirement that the maxi-
mum contaminant level be measured at
the tap except In the case of turbidity,
which should be measured at the point
of entry to the distribution system. How-
ever, the definition lias been expanded
to make clear that contaminants added
to the water by circumstances under the
control of the consumer are not the re-
sponsibility of the supplier of water,
unless the,contaminants result from cor-
rosion of piping and plumbing resulting
from the quality of the water supplied.
It should be noted, however, that this
requirement should not be Interpreted
aa to discourage local, aggressive cross
connection control measures.
Colifobm BacmiA MCL's
The promulgated MCL's for collform
bacteria are basically the 1862 Public
Health Service Standards, with minor
refinements and clarifications. However,
further changes may be desirable. For
example, the MCL's for the membrane
filter analytical method do not resolve
the question of how many collform bac-
teria are assumed to be present in a
single highly contaminated sample.
Some laboratories assume an upper limit
of SO, while others seek to continue to
count Individual bacteria to a level of
100 or even higher In a single sample.
The upper limit assumed will affect the
monthly average which Is calculated to
determine compliance with the MCL's.
Another question relating to the coll-
form bacteria MCL's Is the matter of
possible spurious positive samples. As the
regulations are written, all routine sam-
ples taken to determine compliance with
the MCL's must be counted, regardless
of the results of analysis of any check
samples that may be taken. The reason
for this is that bacterial contamination
is often intermittent or transient, and as
a result negative check samples taken a
day or more after a positive sample can-
not demonstrate that the positive result
was in error. It may be possible, however,
to prescribe a means of dealing frith spu-
rious positive results without compro-
mising the Integrity of the MCL's.
A third question concerning the MCL's
for collform bacteria is the relationship
of monthly averages of collform bacteria
levels to monthly percentages of positive
samples. For example, the monthly av-
erage MCL for the membrane filter
method Is violated if the monthly aver-
age exceeds one coltform bacterium per
sample. However, for purposes of deter-
mining whether the monthly-percent-
age-of-positlve-samples MCL Is violated,
a sample Is counted as positive only if It
, contains more than four collform bac-
teria. Thus, It is possible, particularly
when a relatively small number of sam-
ples Is- taken, for a system to fall the
monthly average MCL even when no sin-
gle sample taken during the month ii
out of compliance with the limit.
These and other questions concerning
the collform bacteria MCL's will be re-
viewed further by EPA. If review indi-
cates that changes In the MCL's are
desirable, those changes will be made as
soon as possible but within Onxoattis, In
time to take effect at the same time as
the initial Interim Primary Drinking
Water Regulations.
. Obqakic Chemicals
The proposed maximum contaminant
levels for organic pesticides, other 'tban
the three which are the subject of can-
cellation and suspension proceedings,
have been retained. It Is anticipated that
additional organic pesticides will be
added to the regulations if surveys of
pesticides in drinking -water being con-
ducted by EPA indicate that this Is
The proposed regulations also con-
tained a maximum contaminant level for
organic chemicals obtained by the carbon
chloroform extract CCCE) method. It
was anticipated by Congress that organic
chemicals would be dealt with primarily
In the Revised Primary Drinking Water
Regulations because of the paucity of ac-
curate data on the health effects of vari-
ous organic chemicals, the large number
of such chemicals, uncertainties over ap-
propriate treatment techniques, and the
need for additional Information on the
incidence of specific organic chemicals
in drinking water supplies. EPA thought
that, the CCE standard might provide an
appropriate means of dealing with or-
ganic chemicals as a class pending action,
on the Revised Primary Regulations.
The CCE standard was originally de-
veloped as a test for undesirable tastes
and odors in drinking water. As concern
developed over the health effects of or-
ganic chemicals, the possibility of using
CCE- as a health standard rather than
an esthetic standard was considered.
As pointed out by numerous comments,
CCE has many failings as an indicator
of health effects of organic chemicals.
To begin with, the test obtains informa-
tion on only a. fraction of the total
amount of organic chemicals In the water
sampled. Furthermore, there Is serious
question as to the reliability of CCE in
identifying those organic chemicals
which are most suspected of adverse
health effects. In addition, there are no
existing data on which a specific level
for CCE can be established on a rational
basis. To establish a maximum contami-
nant level under these, circumstances
would almost certainly do more harm
than good. It could give a false sense of
security to persons served by systems
which are within the established level
and a false sense of alarm to persons
served by systems which exceed the level.
It also would divert resources from
efforts to And more effective ways of
dealing with- the organic chemicals
EPA believes that the Intelligent
approach to the organic chemicals ques-
tion is to move ahead as rapidly as pos-
sible along two fronts. First, EPA is
adopting simultaneously with these reg-
ulations a Subpart E of Part 141, eon-
tainlnf requirements for organic chemi-
cal monitoring pursuant to Sections 1445
and 1450 of the Act. "
The regulations require that desig-
nated public water systems collect sam-
ples of raw and treated water for submis-
sion to EPA for organlcs analysis. SPA
will analyze the samples for a number of
broad organic parameters, including car-
bon chloroform extract (CCE), volatile
and non-volatile total organic carbon
(VTOC and NVTOC), total organic chlo-
rine (TOC1), ultraviolet absorbancy, and
fluorescence. Iaadditlon, monitoring will
be required for probably 21 specific or-
ganic compounds. Selection of the spe-
cific compounds has been based on the
occurrence or likelihood of oeourrence in
treated water, toxicity data and availa-
bility of practical analytical methods.
Laboratory analyses will be used to
evaluate the extent and nature of organic
chemical contamination of drinking
water, to evaluate the validity of .the
general organic parameters as surrogates
for measures of harmful organic chemi-
cals, and to determine whether there is
an adequate basis for establishing maxi-
mum contaminant levels for specific or-
ganics or groups of organics.
Second, EPA is embarking on an inten-
sive research program to find answers
to the following four questions:
1.	What are the effects of commonly
occurring organic compounds on human
2.	What analytical procedures should
be used to monitor finished drinking
water to assure that any Primary Drink-
ing Water Regulations dealing with or-
ganics are met?
3.	Because some of these organic com-
pounds are formed during water treat-
ment, what changes in treatment prac-
tices are required to minimize the for-
mation of these compounds in treated
4.	What treatment technology must
be applied to reduce contaminant levels
to concentrations that may be specified
in the Primary Drinking Water Regu-
This research will involve health-
effects and epidemiological studies, in-
vestigations of analytical methodology,
and pilot plant and field studies of or-
ganic removal unit processes. Some
phases of the research are to be com-
pleted by the end of this year, while
much of the remainder are to be com-
pleted within the next calendar year.
As soon as sufficient Information Is
derived from the monitoring program
and related research, the Interim Pri-
mary Drinking Water Regulations will
be amended so that the organic chemi-
cals problem can be dealt with without
delay. The monitoring process will be
completed within 1 year.
During the interim period, while sat-
isfactory MCL's for organic contamina-
tion in drinking water are being devel-
oped, EPA will act In specific cases where
appropriate to" deal with organic con-
tamination. If the EPA monitoring pro-
gram reveals serious specific cases of
contamination, EPA will work with State
and local authorities to Identify the
source and nature of the problem and to

take remedial action. EPA will akoaid
the Slates is Identifying addintxtat
munJty water supplies that
Public Nones
The public notice requirements pro-
posed in § 141.32 did not distinguish be-
tween community and non-com trwnlty
public water systems. They would hava
required that public notice of non-com-
pliance with applicable regulation* be
~lade by newspaper, in water bills, and
by other media for all puMte water sys-
tems. These requirements are inappro-
priate and ineffective is the case ol most
non-community water systems. Those
systems principally serve transients who
do not receive water bills from the sys-
tem and who probably are not exposed
significantly to the local media. A more
effective approach would be to require
notice that can inform the transient
before he drinks the system's water, and
thereby both warn the transient and
provide an incentive to the supplier of
water to remedy the violation. Accord-
ingly, Section 141.32 as adopted provides
that in the case of non-community sys-
tems, the entity with primary enforce-
ment responsibility shall require that
notice be given in a form and manner
that will Insure that the public using
the public water system is adequately
The proposed public notice require-
ments also failed to distinguish between
different types of violations of the In-
terim Primary Drinking Water Regula-
tions. Since the urgency aijd importance
of a notice varies according to the nature
of the violation involved. 1141.33 as
promulgated seeks to match the type of
notice required with the type of violation
Involved. Written notice accompanying
a water bill or other direct notice by
mail is required for all violations of the
regulations, including violations of mon-
itoring requirements, and for the grant
at a variance or exemption. In addition,
notice by newspaper and notification to
radio and television stations is required
whenever a maximum contaminant level
is exceeded, or when the entity with
primary enforcement responsibility re-
Quires such broader notice.
Quality Control and Testikc
Section 1401(1) of the Act defines
"primary drinking water regulation" to
include "quality control and testing pro- ¦
cedures." The promulgated regulations
include testing requirements for each
maximum contaminant level, including
check samples and special samples in
appropriate cases. The regulations also
specify the procedures to be followed In
analyzing samples for each of the maxi-
mum contaminant levels. These proce-
dures will be updated from time to time
as advances are made In analytical meth-
ods. For example, references to "Stand-
ard Methods for the Examination of
Water and Wastewater" are to the cur-!
rent, 13th, edition, but these references
will be changed to cite the 14th edition
when it Is available in the near future.
A fesp eSB&ont at	-control fior
publfe wateir systems. 3s accurate labora-
tory analysis. Sectbn. L4Ufi-of tha. regu-
lations provides ti»t saaiy«» conducted
for the wrpom o£ determining com-
pliance with maadnmm. contaminant
levels must be caedueted by a labels-tots
approved tiy tha entity with pdmary ea-
foreerntst sesBonaiMIUijc. EPA will de-
velop, m man m posrtttte, to cooperation
with the States and other interested
parties, criteria ami procedure*, for lab-
oratory •emigration. A State wltti ®rt-
mary enforcement re^oasibillty wUl
have a laboratory certified by EPA pur-
suant to the prescribed criteria, ancboro-
cedusai, and in turn will certify laboca-
torles within the State.
Record-keeping requirements and re-
ports to the State also will assist in
quality control efforts.
Adequate record-keeping is necessary
fof the proper operation and administra-
tion of'a public water system. It is also
Important for providing information to
the public, providing appropriate data
for inspection and enforcement activities
and providing information on which fu-
ture regulations can be based. Accord-
ingly, a new f 141.33 has been added to
the regulations to require that each pub-
lic water system maintain .records of
sample analyses and of actions to correct
violations of the Primary Drinking Water
Economic and Cost Analysis
A comprehensive economics study has
been made of the Interim Primary Drink-
ing Water Regulations. This study esti-
mates the costs of the regulations, evalu-
ates the potential economic Impact, and
considers possible material and labor
shortages. The results of this analysis are
summarized here.
Total investment costs to community
water systems to achieve compliance
with these regulations are estimated to
be between $1,050 and $1,765 million. It
is estimated that non-community sys-
tems will invest an additional $24 million.
The range of the estimate is due to un-
certainty as to the design flow that will
be used in Installing treatment facilities.
Systems not in compliance will have to
consider sizing their new components to
reflect average daily flow conditions, or
maximum daily flow conditions to cases,
where system storage Is not adequate.
This investment will be spread over
several years. Investor-owned systems
will bear about one-fourth of these costs,
and publicly-owned systems the remain-
der. It is not anticipated that systems will
have difficulty financing these capital re-
In annual terms, national costs are ex-
pected to be within the following ranges;
In millions
Capital coats				..... *148-247
Operations and maintenance...... 263-363
Monitoring (routine only)	 17- 85
Tatftl 		"$428-645
Although these aggregate figures arc
large, most water consumers will not be
significantly affected. For those users in
systems serving-. 10,000 persons or more,
the average annual- treatment cost per
capita may Increase front lew ttan $1.00
tor systems, requiring dtstafeetlon and
lead control, to between $15 to $33 for.
control of turbidity and h&avy metal re-
moval. For systems serving less than 10Q
persons,'the average minimi ms capita
costs of dlsinfectioa, lend control and
fluoride-iarsenic removal;&re estimated to
be between $2,Wand $11,80, However, if
turbidity control. 
Dated: December 10, 1975.
Rbssell E. Train,
Subpart A—flenent
i«.i Applicability.
i«.2 DaieKiOas.
141-3 Coverage,
141.4	Variances and exemptions.
141.5	Siting requirements.
141.0 BSeetive date.
Subpart B—Mailmum Contaminant Level*
141,11 Maximum contaminant levels for
Inorganic chemicals.
141.13 May I mum contaminant levels for
organic chemicals.
141.13	Maximum contaminant levels for
141.14	Maximum microbiological contami-
nant levels.
Subpart C—Monitoring end Analytical
141.31 Microbiological contaminant sam-
pling and analytical requirements.
FEDERAL REQlStiit, VOL 40, NO. 148—WEDNESDAY, OECtMIH 34, 1973

14123 Turbidity sampling and analytical
141.23 Inorganic chemical sampling and
, analytical require menu.
141-24 Organic chemical sampling and
analytical requirements.
1*121 Alternative analytical techniques.
141.28 Approved laboratories.
14139 Monitoring of consecutive publlo
water systems.
Subpart D—Reporting, Public Notification, and
141.31 Keportl c g req ul rements.
14133 Public notification of variances, ex-
emptions. and non-compliance
with regulations.
141.33 Record maintenance.
AmxoRrrr: Sees. 1412,1414,1448. and 1450
at the Public Health Serrlca Act, 88 Stat. IQ90
(42 U.S.C. M0g-1, 300g-3, 300J-4, and 300J-8),
Subpart A—General
| 141.1 Applicability*
This part establishes primary drinking
water regulations pursuant to section
1412 of the Public Health Service Act, as
amended by the Safe Drinking Water
Act (Pub. L. 93—523); and related regula-
tions applicable to public water systems.
§ 141.2 Definitions.
As used ixt this part, the term:
(a)	"Act" means the .Public Health
Service Act. as amended by the Bale
Drinking Water Act, Pub. L. B3-523.
(b)	"Contaminant" means an? physi-
cal, chemical, biological, or radiological
substance or matter In water.
(c)	"Maximum contaminant level"
means the maximum permissible level of
a contaminant in water which is de-
livered to the free flowing outlet of the
ultimate user of a public water system,
except in the case of turbidity where the
maximum permissible level Is measured
at the point of entry to the distribution
system. Contaminants added to the water
under circumstances controlled. by the
user, except those resulting from corro-
sion of piping and plumbing caused by
water Quality, are excluded from this
(d> "Person" means an Individual,
corporation, company, association, part-
nership, State, municipality, or Federal
Ce) "Public water system" means a
system for the provision to the public
of piped water for human consumption,
If such system has at least fifteen service
connections or regularly serves an aver-
age of at least twenty-five individuals
dally at least 60 days out of the year.
Such terra includes (1) any collection,
treatment, storage, and distribution fa-
cilities under control of the operator of
such system and used primarily in con-
nection with such system, and (2) any
collection or pretreatment storage facili-
ties not under such control which are
used primarily in connection with such
system. A public water system is either
a "community water system" or a "non-
community water system."
(i) "Community water system" means
a public water system which serves at
least 15 service connections used by year-
round residents or regularly serves at
least 25 year-round residents.
(liX "Non-community water system"
mewra public water system that la not.
a community water system.
(f)	"Sanitary survey" means an on-
site review of the water source, facili-
ties, equipment, operation and mainte-
nance of a public water system for the
purpose of evaluating the adequacy of
such source, facilities, equipment, op-
eration and maintenance for producing
and distributing safe drinking water.
(g)	"Standard sample" means the
aliquot of finished drinking water that to
examined for the presence of colifonn
(h)	"State" means the agency of the
State government which has jurisdic-
tion over public water systems. During
any period when a State does not have
primary enforcement responsibility
pursuant to Section 1413 of the Act, the
term "State" means the Regional Ad-
ministrator, US. Environmental Protec-
tion Agency.
(i)	"Supplier of water" means any
person who owns or operates a public
water system.
§ 141.3 Coverage.
This part shall apply to each public
water system, unless the public water
system meets all of the following condi-
(a)	Consists only of distribution and
storage facilities (and does not have any
collection and treatment facilities);
(b)	Obtains all of its water from, but
is not owned or operated by, a public wa-
ter system to which such regulations
ec) Does not sell water to any person:

(1l) CbJoropheaoxja: ,
2,4 - D, (2.4-DlchIaropbenoxyace- 0.1
tic acid),
2,4,5-TP 8U?e* (2,4,6-Titelilore- 0-.Q1
phenoxyproplonlc Mid).
g 141.13 Maximum contaminant levels
lor turbidity.
The maximum contaminant levels fo:
turbidity are applicable to both commu-
nity water systems and non-community
¦water . systems using surface water
sources in whole or in part. The maxi-
mum contaminant levels for turbidity
In drinking water, measured at a repre-
sentative »ntry point (si to the distribu-
tion system, are:
(a)	One turbidity unit (TU), as de-
termined by a monthly average pursuant
to 1141.22, except that five or fewer
turbidity units may be allowed If the
supplier of water can demonstrate to the
State that'the higher turbidity does not
do any of the following:
(1)	Interfere with disinfection;
(2)	Prevent maintenance of an effec-
tive disinfectant agent throughout the
distribution system; or
(3)	' Interfere with microbiological
(b)	Five turbidity units based on an
average for two consecutive days pursu-
ant to § 141.22.
1.141.14 Maximum mierobkilri|gif nl con.
laminant levels.
The maximum contaminant levels for
coliform bacteria, applicable to com-
munity water systems and non-com-
munity water systems, are as follows;
(a) When the membrane filter tech-
nique pursuant to § 141.21(a) Is used,
the number of coliform bacteria shall
not exceed any of the following:
(1) One per 100 milliliters as the
arithmetic mean of all samples examined
per month pursuant to S 141.21 (b) or
<2> Four per 100 milliliters In more
than one sample when less than 20 are
examined per month; or
(3) Four per 100 milliliters in more
than Ave percent of the samples when
20 or more are examined per month.
¦ (b) (1) When the fermentation tube
method and 10 milliliter standard por-
tions pursuant to 1141.21(a) are used,
coliform bacteria shall not be present in
any of the following:
(1)	more than 10.percent of the por-
tions In any month pursuant to 1141.21
(b) or (c);	. •
(li) three or more portions In more
than one sample when less than 20 sam-
ples are examined per month; or
CUD three or more portions in more
than five percent of the samples when
20 or more samples are examined per
(2)	When the fermentation tub#
method and 100 milliliter standard por-
tions pursuant to § 141.21(a) are used,
coliform bacteria shall not be present to
any of the following:
(ii more than 60 percent of the por-
tions in any month pursuant to S 141 21
(b) or (c);
. , (b>(1), m
Chi (2) of this section Rha.ll be bated won.
sampling during a 3 month period, ex-
cept that, at the discretion of the Sfcafi*
compliance may be based upon
during a one-montii period.
Subpart C—-Monitoring and Analytical
S 141.21 Microbiological contaminant
•ampilitf aiul analytical require*
(a)	Suppliers of water for community
water systems and non-community water
systems shall analyse for coliform bac-
teria for the purpose of determining
compliance with 8141.14. Analyses shall
be conducted in, accordance with the an-
alytical recommendations set forth ill
"Standard Methods for the Examination
of Water and Wastewater," American
Public Health Association, 13th Edition,
pp. 662-688, except that a standard sam-
ple size shall be employed. The standard
sample used in the membrane filter pro-
cedure shall be 100 milliliters. The stand-
ard sample used in • the 5 tube most
probable number (MPN) procedure (fer-
mentation tube method) Shall be S times
the standard portion. The standard por-
tion la either 10 milliliters or 100 milli-
liters as described in § 141.14 (b) and (c).
The samples shall be taken at points
which are representative of the condi-
tions within the distribution system.
(b)	The supplier of water for a com-
munity water system shall take coliform
density samples at regular time inter-
vals, and in number proportionate to the
population served by the system. la aa
event shall the frequency be less than as
set forth below:
Minimum number of
Population served: samples per month
38 to 1,000				
I,001	to 2,800		
3,501 to 3,300			
3,301 to 4,100	
4,101 to 4,900	.	
4,901 to 5,800—		
8,801 to 8,700					
8,701 to 7,800	
7,601 to 8,500	
8,801 to 6,400	
9,401 to 10.300.	
10,301 to 11,100	;	
II,101	to 12.000	.	
12,001 to 12,800			
12,901 to 13,700—			
13,701 to 14,000			...
¦14,801 to'16,800			
imoi to ie.aooi-.			
16,301 to 17,200	_	
17,201 to 18,100				...
18,101 to 18,800			
lfl.901 to 18 800			J	
19,801 to 20,700	.	
20,701 to 31,800	.		
31,601 to 22,300..:				
3S30I to 23,200		„
23.201 to 24,000			•	
24,001 to 24,900	
24,901 to 26,000.				
28,001 to 28,000..	_.	
28,001 to'33,000			33
S3,001 to 37,000.					40
37,001 to 41,000	..'.1		48
41,001 to 40,000..						BO
48.001 to 80,000		 		BB
60.001 to 84,000			eo
64,001 to 68,060		l	 _	69
69,001 to 84,000	¦	.....	70"
84,001 to 70,000				 ?S
70,001 .to 78,000					80
7f,001 to 8T,000	i,	....		SS
83.081 to BO.OOO..		j _	' 90
BO.OOi to 88,000-.		'	•	eo
#6,001 to 111,000...		too
111,001 to 180,000				118
130,001 to 160,000			;	.	ISO
160,001 to 190,000		ISO
190,001 to 220,000	...		148
220.001 to 280,000	^				ISO
280,001 to 290,000	-				I«
290.001 to 320,000.			IM
320,001 to 360,000.	......				ISO
880,001 to 410,000	;	180
410,001 to 450.000	...	......		3BO
460,001 to 600.000...		....	310
800,001 to 850,000	....,		210
.660,001 to 600,000	1		230
600.001 to 880,000	 -	340
680.001 to 720.000...			 " 280
720,001 to 780,000-.	i	260
780.001 to 840.000..		 '	270
840.001 «J 810.000			280
910,001 to 670.000		200
870,001 to 1,060.000				300
1,050.001 to 1,140,000		310
1,140.001 to 1,230,000	320
1,280,001 to 1.320|000...'		360
1,320,001 to 1,420,000	i	1		-MO
1,420.001 to 1,620.000	:		390
1,620.001 to 1,630,000	1	;		96Q
1*80,001 to 1,730,600	!		370
1,730,001 to 1,860,000.				3BO
1,850,001 to 1,970,000			890
1,970,001 to 2,060,000					400
2,060,001 to 2,270,000			410
2,278,001 to 2,510,000				420
2,510,001 to 2,760,000		430
2,760,001 to 3,020,000	,	440
3,020,001 to 3.320,000			460
3,320,001 to 3,620,000		460
3,620,001 tc 3.980,000		474
8,980,001 to 4,310,000				480
4,310,001 to 4.690,000		 •	490
4,890,001 or more	j		600
Based on a history of no coliform bac-
terial contamination and on a sanitary
¦urvey by the State showing the water
system to be supplied solely by a pro-
tected ground water source and free of
sanitary defects, a community water sys-
tem serving 25 to 1,000 persons, wito
written permission from the State, may
reduce this sampling frequency except
that in no case shall it be reduced to less
than one per quarter.
(c).	The supplier of water for a non-
community water system shall sample for
" coliform bacteria in each calendar quar-
j". ter during which the system provides
ig water to the public. Such sampling shall
ia begin within two years after the effective
14 date of this put. If the State, on the
18 basis of a sanitary survey, determines
16 that some other frequency is more appro-,
J* priate, that frequency shall be the fee-
jg quency required under these regulations.
20	Sueh frequency shall be confirmed on
21	changed on the basis of subsequent
as surveys.
(d)(1)	Wken the coltfoxm bacteria in a
H single sample, exceed four per 100 milli-
ng liters (3141.14(a)), at least two consecu-
27	tlve daily check samples shall be collected
28	and examined from the same sampling
29	point. Additional check samples shall be
30	collected dally, or at a frequency estab-

llshed by the State, until the results ob-
tained from at least two consecutive
check samples show less than one con-
form bacterium per 100 milliliters.
(2)	When collfortn bacteria occur in
three or more 1ft ml portions of a single
sample (§ 141.14(b) (1) 5, at least two
consecutive dally check samples shall be
collected and examined from the same
sampling point. Additional check samples
shall be collected dally, or at a frequency
established by the State, until" the results
obtained from aHeast two consecutive ¦
check samples show no positive tubes.
(3)	When collform bacteria occur in all
five of the 100 ml portions of a single
sample <| 141.14(b) (2)), at least two
dally check samples shall be collected
and examined from the same sampling
point,'Additional check samples shall be
collected dally, or at a frequency estab-
lished by the State, until the results ob-
tained from at least two consecutive
check samples show no positive tubes.
(4)	The location at which the check
samples were taken pursuant to para-
graphs (d) (1), (2». or (3) of this section
shall not be eliminated from future sam-
pling without approval of the State. The
results from all collform bacterial analy-
ses performed pursuant to this subpart,
except those obtained from check sam-
ples and special purpose samples, shall be
used to determine compliance with the
maximum contaminant level for collform
bacteria as established In § 141.14. Check
samples shall not be Included In calculat-
ing the total number of samples taken
each month to determine compliance
with § 141,21 (b) or (e>.
 (1), ,(2), or (3) of this
section, the supplier of water shall re-
port to the State within 48 hours.
(f)	When a maximum contaminant
level set forth in paragraphs (a), (b) or
(c) of 5141,14 Is exceeded, the supplier
of water shall report to the State and
notify the public as prescribed In I 141,31
and i 141,32.
(g)	Special purpose samples, such as
those taken to determine whether dis-
infection practices following pipe place-
ment, replacement, or repair have been
sufficient, shall not be iued to determine
compliance with § 141.14 or § 141.21 (b)
or (c).
(h> A supplier of water of a com-
munity water system or a non-com-
munity water system may, with the
approval of the State and based upon -a
sanitary survey, substitute the use of
chlorine residual monitoring for not more
than 75 percent of the samples required
to be taken by paragraph (b) of this
section, Provided, That the supplier of
water takes chlorine residual samples at
points which are representative of the
conditions within the distribution sys-
tem at the frequency of at least four for
each substituted microbiological sample.
There shall be at least daily determina-
tions of chlorine residual. When the sup-
plier of water exercises. the option pro-
vided In this paragraph (h) of this
section, he shall maintain no less than
0,2 mg/1 free chlorine throughout the
public water distribution system. When a
particular sampling point has been
shown to have a free chlorine residual
less than 0.2 mg/1, the water at that loca-
tion shall be retested as soon as prac-
ticable and In any event within one hour.
If the original analysis Is confirmed, this
fact shall be reported to the State within
48 hours. Also, if the analysis Js con-
firmed, a sample for collform bacterial
analysis must be collected from that
sampling point as soon as practicable and
preferably within one hour, and the re-
sults of such analysis reported to the
State within 48 hours after the results
are known to the supplier of water.
Analyses for residual chlorine shall be
made in accordance with "Standard
Methods for the Examination of Water
and Wastewater," 13th Ed., pp. 129-132,
Compliance with the maximyrn con-
taminant levels for collform bacteria
shall be determined on the monthly mean
or quarterly mean basis specified In
1141,14, including those samples taken
as a result of failure to maintain the re-
quired chlorine residual level. The State
may withdraw its approval of the use of
chlorine residual substitution at 'any
§ 141.22 Turbidity sampling and an-
alytical retirements.
(a)	Samples shall be taken by suppliers
of water for both community water sys-
tems and non-community water systems
at a representative entry point  The requirements of this § 141.22
shall apply only to public water systems
which use water obtained In whole or In
part from surface sources.
§ 141.23 Inorganic chemical sampling
and analytical requirements.
. (a) Analyses for the purpose of de-
termining compliance with § 141.11 are
required as follows;
(1)	Analyses for all community water
systems utilizing surface water sources
shall be completed within one year fol-
lowing the effective date of thla part,
These analyses shall be repeated at
yearly intervals.
(2)	Analyses for all community water
systems utilizing only ground water
sources shall be completed within, two
years following the effective date of this
part. These analyses shall be repeated
at three-year intervals.
(3)	For non-community water systems,
whether supplied by surface or ground
water sources, analyses for nitrate shall
be completed within two years following
the effective date of this part. These
analyses shall be repeated at Intervals
determined by the State,

mental Protection Agency, Office of
Technology Transfer, Washington, D.C.
(2)	Barium—Atomic Absorption Meth-
od, "Standard Methods for the Exami-
nation of Water and Wastewater," 13th
Edition, pp. 210-215, or "Methods for
Chemical Analysis of Water and Wastes,"
pp. B7-B8, Environmental Protection
Agency, Office of Technology Transfer,
Washington, D.C. 20480, 1974.
(3)	Cadmium—Atomic Absorption
Method, "Standard Methods for the Ex-
amination of Water and Wastewater,"
13th Edition, pp. 210-215, or "Methods
for Chemical Analysis of Water and
Wastes," pp. 101-103, Environmental
Protection Agency, Office of Technology
Transfer, Washington, D.C. 20460, 1974.
(4)	Chromium—Atomic Absorption
Method, "Standard Methods for the Ex-
amination of Water and Wastewater,"
13th Edition, pp. 210-215, or "Methods
for Chemical Analysis of- Water and
Wastes," pp. 10S-1Q8, Environmental
Protection Agency, Office of Technology
Transfer, Washington, D.C. 20460, 1974.'
(5>~ Lead—Atomic Absorption Method,
"Standard Methods for the Examina-
tion of Water and Wastewater," 13th
Edition, pp. 210-215, or "Methods for
Chemical Analysis of Water and Wastes,"
pp. 112-113, Environmental Protection
Agency, Office of Technology Transfer,
Washington, D.C. 20460, 1914.
(6)	Mercury—Flameless Atomic' Ab-
sorption Method, "Methods for Chemical
Analysis of Water and Wastes,", pp. 118-
128, Environmental Protection Agency,
Office of Technology Transfer, Wash-
ington, D.C. 20460,1874.
(7)	Nitrate—Brucine Coloiimetric
Method, "Standard Methods for the Ex-
amination of Water and Wastewater,"
13th Edition, pp. 481-484, or Cadmium
Reduction Method, "Methods for Chemi-
cal Analysis of Water and Wastes,"
pp, 201-209, Environmental Protection
Agency, Office of Technology Transfer,
Washington, D.C. 20480,1974.
<8> Selenium—Atomic Absorption
Method, "Methods for Chemical Analysis
of Water and Wastes," p. 145, Environ-
mental Protection Agency, Office of
Technology Transfer, Washington, D.C.
(9)	Silver—Atomic Absorption Meth-
od, "Standard Methods for the Ex-
amination of Water and Wastewater",
13th Edition, pp. 210-215, or "Methods
for Chemical Analysis of Water and
Wastes", p. 146, Environmental Protec-
tion Agency, Office of Technology Trans-
fer, Washington, D.C. 20480, 1974.
(10)	Fluoride—Electrode Method,
"Standard Methods for the Examination
of Water and Wastewater", 13th Edition,
pp. 172-174, or "Methods for Chemical
Analysis of Water and Wastes," pp, 65-
67, Environmental Protection Agency,
Office of Technology Transfer,. Wash-
ington, D.C. 20460, 1974, or Colorimetric
Method with Preliminary Distillation,
"Standard Methods for the Examination
of Water and Wastewater," 13th Edition,
pp. 171-172 and 174-178, or "Methods for
Chemical Analysis of Water and
Wastes," pp. 59-60, Environmental Fro-
tection Agency, Office of Technology
Transfer, Washington, D.C. 20480. 1974.
§ 141.24 Organic chemical iampling
and analytical requirement*.
(a)	An analysis of substances for the
purpose of determining compliance with
§ 141.12 shall be made as follows:
(1)	For all community water systems
utilizing surface water sources, analyses
shall be completed within one year fol-
lowing the effective date of this part.
Samples analyzed shall be collected dur-
ing the period of the year designated by
the State as the period when contami-
nation by pesticides-is most likely to
occur. These analyses shall be repeated
at intervals specified by the State but
in no event less frequently than at three
year Intervals.
(2)	For community water systems
utilizing only ground water sources,
analyses shall be completed by those sys-
tems specified by the,State,
(b)	If the result of an analysis made
pursuant to paragraph (a) of this sec-
tion indicates that the level of any con-
taminant listed in I 141.12 exceeds the
"maximum contaminant level, the sup-
plier of water'shall report to the State
within 7 days and Initiate three addi-
tional analyses within one month.
Cc) When the average of four analyses
made pursuant to paragraph (b) of this
section, rounded to the same number of
significant figures as the maximum con-
taminant level for the substance In ques-
tion, exceeds the mpximum contaminant
level,- the supplier of water shall report
to the State pursuant to § 141.31 and give
notice to the public pursuant to S 141.32.
Monitoring after public notification shall
be at a frequency designated by the State
and shall continue until the maximum
contaminant level has not been exceeded
In two successive samples or until a
monitoring schedule as a condition to a
variance, exemption or enforcement ac-"
tion shall become effective.
Cd> For the initial analysis required
by paragraph (a) (1) and (2) of this
section, data for surface water acquired
within one year prior to the effective
date of this" part and data for ground
water acquired within three years prior
to the effective date of this part may .be
substituted at the discretion of the State.
te) Analyses made to determine com-
pliance with § 141.12(a) shall be made
in accordance with "Method for Organo-
chlorlne Pesticides in Industrial Efflu-
ents," MDQARL, • Environmental Pro-
tection Agency, Cincinnati, Ohio, Novem-
ber 28, 1973.
 Analyses'made to determine com-
pliance with 1141.12(b) shall be con-
ducted in accordance with "Methods for
Chlorinated Phenoxy Acid Herbicides In
Industrial Effluents," MDQARL, En-
vironmental Protection Agency, Cincin-
nati, Ohio, November 28, 1973.
§ 141.2? Alternative analytical tech-
With the written permission of the
State, concurred in by the Administra-
tor of the U.S. Environmental Protec-
tion Agency, an alternative analytical
technique may be employed. An alterna-
tive technique shall be acceptable only
if it is substantially equivalent to-.the
prescribed test In both precision and ac-
curacy as it relates to the determination
of compliance with any maximum con-
taminant level. The use of the alterna-
tive analytical technique shall not de-
crease the frequency of monitoring re-
quired by this part.
§ 141.28 Approved laboratories.
For the purpose of determining com-
pliance wifchj 141.21 through.| 141.27,
Samples may be considered only If they
have been analyzed by a laboratory ap-
proved by the State except that meas-
urements for turbidity and free chlorine
residual may be performed by any per-
son acceptable to the State.
§ 141.29 Monitoring of consecutive pub-
lic water systems.
When a public water system supplies
water, to one or more other public water
systems, the State may modify the moni-
toring- requirements imposed by this
part to the extent that the interconnec-
ion of the sysems Jusiftes treating them
as a single system for monitoring pur-
poses. Any modified monitoring shall be
conducted pursuant to. a schedule speci-
fied by the State and concurred in by the
Administrator of the U.S. Environment*!
.Protection Agency.
Subpart D—Reporting, Public Notification
and Record Keeping •
§141.31 Reporting requirement*.
(a)	Except where a shorter reporting
period is specified in this part, the
supplier of water shall report to the State
within 40 days following a test, measure-
ment or analysis required to be made by
this part, the results of that test, meas-
urement or analysis.
(b)	The supplier of water shall report
to the State within 48 hours the failure
to comply with any primary drinking
water regulation (including failure to
comply with monitoring requirements)
set forth in this part.
' fc) The supplier of water is not re-
quired to report analytical results to the
State in cases where a State laboratory
performs the analysis and reports the
results to the State office which would
normally receive such notification from
the supplier.
§ If 1.32 Public notification,
(a) If a community water system falls
to comply with an applicable maximum
contaminant level established in Subpart
B, fails to comply with an applicable
testing procedure established in Subpart
C of this part, is granted a variance or
an exemption from an applicable maxi-
mum contaminant level, falls to comply
with the requirements of any schedule
prescribed pursuant to a variance .or ex-
emption, or fails to perform any moni-
toring required pursuant to Section. 1445
(a) of the Act, the supplier of water shall
notify persons served by the system of
the failure or grant by inclusion of a no-
tice In the first set of water bills of the
system issued after the failure or grant

and In any event by written notice within
three months. Such notice shall be re-
peated at least once every three mosttas
bo long as the system's failure continues
or the variance or exemption remains In
effect. If the system lisues water bills less
frequently than Quarterly,- or does not
Issue water bills, the notice shall be made
by or supplemented by another form of
direct mall.
 Notices given pursuant to this sec-
tion shall be written In a manner reason-
ably designed to Inform fully the users
of the system. The notice shall be con-
spicuous and shall not use unduly tech-
nical language, unduly small print or
other methods which would frustrate the
purpose of the notice. The notice shall
disclose all material facts regarding the
subject Including the nature of the prob- ,
lem and, when appropriate, a clear state-
ment that a primary drinking water
regulation has been violated and any pre-
ventive measures that should be taken by
the public. Where appropriate, or where
designated by the State, bilingual notice
shall be given. Notices may include a bal-"
aaced explanation of the significance or
BBrtous&ess to the public health of the
subject of the notice, a fair explanation
of steps taken by the system to correct
any problem and the results of any addi-
tional sampling.

BO comments were received en this section.
In response to comments asking lor clarifi-
cation of the section, It has been revised to
make clear that a public water system must
meet each of the four listed conditions in
order to be exempted from the regulations.
Thus, a public water system Is exempted only
if it consists only of distrlbuttoa-and storage
facilities and It obtains all of Its water from,
but Is not owned or operated by, a public
water system to which the regulations ap-
ply, and It does not sell water and it is not
a carrier which conveys passengers In Inter-
state commerce. Interstate carriers, there-
lore, are not "exempted, even If they have
only storage and distribution facilities, ob-
tain all their water from a public water sys-
tem, and do not sell water to the public.
However, a public facility such as a hotel or
restaurant is exempted if it has only storage
and distribution facilities, obtains- all its
¦water from a public water system and does
not sell water to the public.
Of course, many facilities serving tran-
sients obtain water by direct connection to
a conventional water utility system and
either do not constitute a separate system or
are excluded from coverage because they
meet all four of the conditions listed in
i 141.3. And In some cases, such as gasoline
stations, even when the facility has Its own
water system It often will not qualify as a
public water system because It does not serve
water to the requisite number of service con-
nections or persons.
2.	"Community Water System." Two com-
ments requested clarification of the defini-
tion of a "community water system," 5 141,2,
The purpose of defining this term is to allow
appropriate regulatory distinctions between
public water systems which serve residents
on a year-round basis and public water sys-
tems which principally serve transients or
Intermittent users. Different monitoring re-
quirements are appropriate for the two types
of systems, and, as discussed below, some
maximum contaminant levels are not appli-
cable to non-community systems,
The proposed regulations defined "com-
munity water system" as "a public water sys-
tem which serves a population at which 70
percent or greater are residents."' This defini-
tion distinguished community systems on the
basis of service to residents, but it excluded
a number of systems which serve a large
number of residents throughout the year. For
example, some large resort communities may
have several hundred or even several thou-
sand year-round residents who nevertheless
mate up less than 70 percent of the popula-
tion of the community at any given time.
"Water systems In such communities should
he treated as "community systems" In order
to provide appropriate protection for the
year-round residents in the community.
Thus, the definition of a "community water
system" has been revised to cover any system
which, serves at least 15 service connections
used by year-round residents or serves at
least 25 year-round residents,
A definition for "non-community system"
has been added to make it clear that a public
water system Is categorized as being either
a community or a non-community system,
3.	"Maximum contaminant level" and
"contaminantOver 160 comments were di-
rected to the definition of "maximum con-
taminant level" or the definition of "con-
The definition of "contaminant" contained
in 8 141.2 wa3 criticized for its breath. The
term as defined includes virtually any con-
stituent in water, including constituents
considered to be harmless or even beneficial.
The definition was taken directly from Sec-
tion 1401(6) of the Act. It la not Intended
to suggest that all constituents In water are
undesirable, but rather Is intended to per-
mit the regulation of any constituent which
Bay be found to be harmful. The definition
has been retained as proposed.
The definition of "maximum contaminant
level" was criticized for requiring measure-
ment of the level at the "free-flowing outlet
of the ultimate user of a public water sys-
tem." This definition carries out the Intent
of Congress that "drinking water regulations
are Intended to b« met at the consumer's
tap." (H. Rep. No. 93-1185, Si3rd Cong., 2nd
Bern. 13 (1814)). The purpose of the Primaty
Drinking Water Regulations la to assure that
water used by the public is safe.'This call
be assured only if maximum contaminant
levels are met at the tap.
The final regulations retain tie require-
ment that maximum contaminant levels be
met at the consumer's tap, but have been
amended to meet the point mad® to. many
comments that a public water system can-
not be held responsible for contamination of
water which is the fault of the consumer. It
would be unreasonable to hold a public
water system In violation of a maximum con-
taminant level If the level Is exceeded at the
consumer's tap as a result of the user's at-
tachment of a faulty home treatment device,
because of cross-connections to the user's
plumbing system or because the plumbing Is
used to ground electrical systems. The defini-
tion of "maximum contaminant level" In
I 141.2(d) therefore provides that "Con-
taminants added' to the water under circum-
stances under the control -of the user, except
those resulting from corrosion of piping and
plumbing caused by water quality, are ex-
cluded from this definition." This wording
Is not meant to deter or to detract from the
maintenance of a cross-connection control
program by the supplier.
The proposed definition provides for
measurement of turbidity at the point of
entry to the distribution system, rather than
at the consumer's tap, since measurement of
turbidity at this point is a more meaningful
indicator of the sanitary quality of the water,
4.	"Sanitary survey:' A definition of the
term, "sanitary survey" has been added as
i 141.2{f>, because sanitary surveys are re-
ferred to at several points In the fiDal regula-
tions. Comments from many sources. Includ-
ing the National Drinking Water Advisory
Council, urged EPA to emphasize the im-
portance of sanitary surveys of public water
systems as a means of assuring that Primary
Drinking Water Regulations will be met. The
definition contained In the regulations re-
flects the broad extent of adequate sanitary
surveys. Including on-site review of the water
source, facilities, equipment, operation and
maintenance of a public water system,
5.	Other definitions, other comments w^rs
received on the definitions of "person" and
"supplier of water". These defintilons were
taken, directly from section 1401 of the Act,
and have been retained In the final regula-
tions. As In the case of some comments on
the definition of "public water system," a
number of these comments were based on an
erroneously restricted view of the coverage
of the Act. As noted above. Congress Intended
that Primary Drinking Water Regulations
apply to a broad range of facilities with their
own water systems, not Just to conventional
water_ utilities. The owner or operator of a
restaurant or motel, for example. Is a "sup-
plier of water" If the faculty has Its own
water system and serves the requisite num-
ber of service connections or persons.
It. Inorganic Chemicals
1.' General Comments. Comments on maul-
mum contaminant levels ("MCL'b") for In-
organic chemicals (5 141.11) included ques-
tions on the analytical aspects of the
MCL's—whether these were total or dissolved
levels, whether the analytical methodology
was adequate for the cited levels, whether an
allowance had .been made for analytical
variations, and Whether the public water sys-
tem's laboratory or some other laboratory
would be performing the analyses. The Ad-
ministrator has verified that all of the sub-
stances for which MCL's have been specified
can be measured readily by available meth-
odology at the applicable levels. The ana-
lytical methods cited In these regulations
provide information on analytical variability,
and the check-sample and averaging tech-
niques cited -in I 141.23 provide additional
allowances for human or mechanical errors.
Two comments urged that MCL's for In-
organic chemicals be deferred until issuance
of the report of the National Academy of
Sciences pursuant to Section 1412(b) of the
Act. However, It was the Intent of Congress
that the Interim Primary Drinking Water
Regulations be promulgated as soon a* poa>
Elble, so that at least minimal protection to •
water'consumers would be available during
the period that the Academy Is preparing
that report.
2.	Water consumption. The MCIj'b for In-
organic chemicals and other contaminant!
are bused,-on an Individual consumption
rate of two liters of water per day, Fourteen
comments agreed with the two-liter figure
or contended that a lower figure should be
used. Pour comments urged the adoption of
a higher consumption figure. An environ-
mental organization submitted data indi-
cating that soma segments of the population,
such as foundry workers and heavy drinkers,
consume an average of susbtantlally more
than two liters per day.
EPA's assumption of a two liter per' daj
water intake rate was based on evidence that
the average consumption of adult males is
at a rate of 1,25-1 5 liters per day and that
the average consumption rate of women
and children is even lower. Because Congress
intended that susceptible groups in the pop-
ulation should be protected to the extent
feasible, the use of a two-liter figure provides
protection for the great majority of the popu-
lation which consumes an average amount of
water, or less than, an average amount, or
even as much as one-third more than the
average amount. To base all maximum con-
taminant levels on the water consumption
rate of the small percentage of the population
which drinks much more water each day
would be unrealistic and enormously expen-
This is not to say that the maximum con-
taminant levels do not protect persons who
drink water at a substantially higher rate'
than normal. As Indicated below, critical
maximum contaminant levels have substan-
tial safety factors. The safety factors for
persons drinking unusually large quantities
of water are not as high as those for the
majority of the population, but they do pro-
vide a reasonable degree of protection under
the circumstances,
3.	Safety factors. One set of comments
questioned the fact that different safety
factors are contains! in various proposed
maximum contaminant levels. The group
commenting agreed that a uniform safety
factor should not be used, but requested a
more systematic discussion of safety factors.
at least with respect to inorganic chemicals.
The regulations are, as anticipated by Con-
gress, based on the 1B8S Public Health Serv-
ice Standards, as reviewed in 1873 by the EPA
Advisory committee. The standards were not
developed by a systematic approach to safety
factors, at least partly because of amount of
knowledge about, and the nature of the
health risk of, the various contaminants cov-
ered a very broad range. The regulations are
the result or experience, evaluation of the
available data, and professional review.
In the Statement of Basis and Purpose for
these regulations, the safety factor repre-
sented by a number of the maximum con-
taminant levels for Inorganic chemicals was
estimated. The purpose of this was to deter-

bulk js®
mine whether the estimated safely factor was
roughly consistent with the type of Informa-
tion available and the nature or the health
risk presented. It was Dot intended to re-
write the regulations on the basis of esti-
mated safety factors.
The National Academy of Sciences has bees
asked to review each of the substaaeos for
which amwlmum contaminant levels are be-
ing get, ss part of the NAS study for the
adoption of Revlssd Primary Drinking Water
Regulations. Any new Information obtained
by NAS on the safety factors Involved will
be carefuMy analysed by EPA.
4.	Artenic. Thirteen comments addressed
the proposed MCL for arsniia (1141.11(a)).
Most comments regarding arsenic recom-
aoended an MCL of 0.1 mg/l on the basis that
-lie adverse health effects have been demon-
strated from the consumption of water con-
taining this amount.
The Administrator has considered raising
me arsenic limit to 0.1 mg/l for the same rea-
son cited In many comments—no adverse
health effects bare been demonstrated from
oaaaumption of water containing thla
amount or more, at least not in this country.
However, arsenic he* been shown to be a po-
tential carcinogen la some of Its forms la
Industrial exposures, and there appears to he
& correlation between arsenic levels In drink-
ing water and the occurrence of skin cancer
In other countries. While the role of arsenlo
M a carcinogen or co-carcinogen has not been
flrmly established, It does not seem to be pru-
dent at this time to raise the arsenic limit.
5.	Barium. Two comments concerned the
MCL for barium, and both expressed concern
over required compliance when the MCL la
exceeded aa the result of naturally occurring
barium In ground water.
Maximum contaminant levela apply equal-
ly to naturally occurring substances and
those occurring aa the result of man-made
pollution. When barium is found to exist In
a ground water source, the course of action
is to attempt Its removal, such as by conven-
tional water treatment processes or ton ex-
change, or to obtain a different water source.
IS such action Is not feasible, the system can
seen a variance or exemption under the pro-
visions of these and subsequent regulations.
0.	Cadmium. Three comments suggested
that the cadmium limit should be revised to
allow more protection for cigarette b makers,
while 49 comments emphatically denounced
'the concept of having non-smokers bear the
flnanclat burden of lowering the cadmium
limit for the benefit of smokers, The Admin-
istrator U aware of the fact that smokers will
T» provided a smaller factor of safety on the
basis of the cadmium limit, but ha agrees
with the majority that a reduction of the
limit cannot be Justified.
1,	Chromium, The seven' comments on the
MCL for.chramlum included suggestions that
the limit be raised, that It be eliminated, or
that it be apeclfted as only for hexavalent
The limit for chromium is baaed on the
known toxicity of the hexavalent form. Since
this form is the one most likely to be found
In drinking water, and since the specified
analytical detection method (atomic absorp-
tion spectrophotometry) does not distinguish
between the valence states, the MCL W
for total chromium. If part of the chromium
present la In a lower valence state, the MCL
provides an additional margin of safety,
8. Cyanide. There were only two comments
on the MCL tor cyanide—one stating that the
MCL was too low and one stating that the
limit was based on insufficient data, Since
small amounts of cyanide do not constitute
a health hazard, and since cMortnatlon fur-
ther reduces the toxicity of cyanide, this sub-
stance Is rarely a problem in drinking water,
and there appears to be no justification for
including cyanide in the list of inorganic
chemicals lift which MCL's ars BstaWlsiwI Ja
these Regulations. Cyanlda tuts not fteea
identified tfnrtzw; rcruUire ramp ling of drink-
ing- water in ooncentratlons greater thorn Us
of the proposed ISCL. which itself is Woo of
the level at which cyanlfflo has adverse health
effects on humans. It does cot appear that
there Is Juuaflcatltm for requiring tens of
thousands of communities to monitor tear
this substance*. Further, cyanide occurs, how-
ever rarely, in drinking water primarily at «
result of spills or other accidents, which ess
be more appropriately controlled by other
laws or regulations, such as Section 1431 of
the Act, The Administrator, therefore, has
decided to withdraw cyanide from th# In-
terim Primary Drinking Water Begulatkras,
The States may require monitoring for cy-
anide lh appropriate circumstances,
9.	Lead. The one comment on the MCL for
lead stated that the limit la too low and
that it la below or near the detection limit.
The Administrator has verified that the
atomic absorption spectrophotometric meth-
od specified has the necessary sensitivity for
detection of the metal at the specified con-
10.	Fluoride. The 94 comments on the fiuo;
ride MCL's catered aa extremely broad area.
Among the comments were suggestions that
a single MCL of 0.05 mg/l, of 1.5mg/l, of
1.8 tag/l, of a.o mg/l, of 2A mg/l, of 2-5 EOf/l,
or of 6.0 mg/l be used in place of those lh
the regulations. There also were suggestions
that different ranges be used, and that the
reason for temperature-dependent MCL's be
given. Some comments requested that fluo-
ride be deleted from the regulations, or at
least placed In Secondary Drinking Water
Regulations. Quite a number of comments
were directed toward controlled fluoridation
rather than MCL's for fluoride. Some per-
sons registered their objections to controlled
fluoridation, while others requested that
limits for controlled fluoridation be included
in the regulations. There were comments
that all fluoride should he removed from
drinking water, and comments that there
should he no limit on fluoride. There were
comments that water supplies serving tran-
sients be excluded from the fluoride limits,
and comments that educational Institutions
should not be excluded.
The fluoride question has been complicated
by the fluoridation controversy. It was clearly
the Intent of Congress that Primary Drink-
ing Water Regulations not be used aa the
vehicle for a national fluoridation program
(House Report, p. IS). At the same time.
Congress made It clear that there was no
intent to prohibit or discourage fluoridation.
As for changing the MCL's, either raising or
lowering them, very little data were sub-
mitted to support the recommendations.
Suggestions that the MCL's be lowered
were for the most part based on presumed
toxicity of fluoride or on presumed increased
exposure to fluoride from sources other than
water. The evidence available to the Admin-
istrator indicates that the toxic effect of
fluoride In drinking water ia limited ta mot-
tling of dental enamel and minor changes
In bone density, and that these effects occur
primarily at fluoride concentrations above
the proposed MCL's. It has been postulated
that, with the advent of controlled fluorida-
tion, the overall exposure of Individuals to
fluoride has increased to the point where" the
addition of more fluoride to drinking water
Is no longer necessary, or perhaps even to
the point where lower MCL's In water ought
to be established. 'While It Is true that foods
prepared In fluoridated water contribute
fluoride to the diet In addition to that ob-
tained from drinking water, it should be
noted that the fluoride MCL's are based al-
most entirely on epidemiological evidence
obtained from areas where fluoride te a nat-
ural. constituent of the water. It can be
assumed that In such areas most food was
prepared In the local water, so the contri-
bution- of fluoride from, this source was auto-
matically taken Into account; '
This sane epidemiological evidence showed
that there is a temperature-dependent
physiological effect of fluoride, both benefi-
cial and detrtmmSBl depending on concen-
tration. To ignore this endeacs would ewa
to be most unwise. The use of a temperatufs
•sale for Saorlde U snore appropriate than
for other chemicals because of the atudle*
amUablt on the fluoride-temperature (*!&¦
tloaship and because there la & small margin
with fluoride between beneficial level* and
levels with adverse health effects.
• Suggestions that the MCL's be raised or
eliminated were based on the tatarpretatlan
of dental fluorosis as an esthetic oondltlcm
rather than as a health problem or em the
economic aspects-of fluoride removal. The
Administrator has available to him a wealth
of information on the subject of ftuorldm,
plus the advice and counsel of the dentftl
experts at the National Institutes of Health,
DHEW. On the basis of this Information
and counsel, the Administrator believes that
the MCL's In these regulation* are adequate
for the protection of the health of consumer*,
and that there is insufflcieat evidence to
Justify altering the proposed MCL'a. While
the Administrator believes that the tmmp-
tlon of educational Institutions from the
fluoride limits was justified, revision of the
regulations to exclude non-community pub-
lic water systems from most tnorgattlc chem-
ical MCL's will make the exemption provi-
sion unnecessary.	¦''
11.	Mercury. Six comments contained sug-
gestions that the mercury limit be left aa
proposed except that it ba applied only t»
methyl mercury; seven comments suggested
that a limit be set for organic mercury only:
and 29 comments expressed agreement with
the proposed limit—a limit based on the
health hazard of methyl mercury but meas-
ured as total mercury. One commwt ox-
pressed dissatisfaction with mercury limits
in general, on the basis that the mercury
problem has been gtosnly exaggerated.
A specific limit for organic mercury, or
designating the proposed limit as applicable
only to organic mercury, both present prob-
lems In analysis, and do not provide for
potential conversion of inorganic mercury to
the organic form. Since the proposed limit
for total mercury la based on the "worst
case" concept, that la, presumes tbat all mer-
cury present is In the more toxic, organic
form,"it provides maximum health protec-
tion. Because of the low levels of mercury
found In drinking water, the economic Im-
pact of the proposed limit la expected to be
minimal. The Administrator therefore is sat-
isfied that the proposed limit for mercury Is
generally acceptable.
12.	Nitrate. Meet of the 21 comments on the
nitrate MCL were directed toward naturally
occurring nitrate and the difficulty In meet-
ing the limit. As explained in the Statement
of Basis and Purpose, nitrate can be toxic
to infants. Because of the • known adverse
health effects ol nitrate, the Administrator
believes that an MCL for nitrate should be
set, "While It Is acknowledged that removal
of nitrate from drinking water is difficult. In
many cases the sources of nitrate can be
Identified and steps taken to ptaveat Its entry
into drinking water sources. An example Is
the nitrate contamination of pound water
as the result of surface run-off, Bach con-
tamination can often be eliminated by proper
well construction.
13.	Sodiwn. Several comments suggested
the possibility of an MCL for sodium and the
National Drinking Water Advisory Council
recommended that consideration tie given to

monitoring for sodium aa that thfl public can
bo Informed of the sodium content of avail-
able water. These concerns result from the
fact that many persons In the United States
suffer from dtaases which. are Influenced by
dietary sodium Intake, In addition, persona
ma; wish to limit their sodium Intake for
other reasons. However. EPA haa not pro-
posed am MCL for sodium, and the Advisor?
Council did not reoommend. an MCL, because
the data avail able do not support any par-
ticular level for sadism In drinking water,
and because regulation of sodium by an MCi
is a relatively inflexible, very expensive means
of dealing with a problem which varies great-
ly from person to person.
EPA has requested the National Academy
of Sciences to Include sodium to Its study
of the health effects of Inorganic chemicals.
In the meantime, the Agency recommends
that the States institute monitoring pro-
grams for sodium, and that physicians and
consumers be Informed of the sodium con-
centration in public water systems bo that
they can take action thsy may consider ap-
14.	Sulfate. Comments also were submitted
urging the adoption of an MCL for sulfate.
Am in the case of sodium, the National Drink-
ing Water Advisory Council recommended
monitoring for sulfate levels, but did aot
recommend the adoption of a maximum con-
taminant level.
The auirate question is similar to the
sodium question in that available data do
not support the establishment of any given
level. A relatively high concentration of sul-
fate in driiiStlng water has tittle or no known
effect on regular users of the water, but
transients using high sulfate water some-
times experience a laxative effect. Whether
this effect will occur, and its severity, varies
greatly with such factors as the level of mil-
fate In the water being consumed and the
level of sulfate to which the transient is ac-
customed. EPA recommends that States in-
stitute monitoring programs for sulfates, and
that transients he notified if the sulfate con-
tent of the water Is high. Such notification
should Include an assessment of the possible
physiological effects of consumption of the
The National Academy of Sciences has
"been asked to consider sulfate in Its study.
An MCL for sulfate will be proposed If It is
supported by the available data.
15.	Inorganic chemical MCL's /or non-
community systemt. As proposed, the regu-
lations would have made all MCL's for in-
organic chemicals applicable to non-com-
munity water systems. This approach failed
to take into account.the fact that the pro-
posed MCL's for inorganic chemicals, except
nitrates and cyanide, were baaed on the po-
tential health effects of full-time, long-term
exposure. MCL's based on full-time long-
term exposure are not necessary to protect
transients or intermittent users served by
non-community systems. Therefore, the final
regulations provide that MCL 'a for inorganic
chemicals other than nitrates are not ap-
plicable to non-community systems. Nitrates
are applicable to all public water system* be-
cause they can have an adverse health effect
on susceptible infants In a short period of
time after exposure. (As discussed above, the
other proposed Inorganic chemical MCL
based on short-term effects—cyanide—has
been deleted.)
16.	Monitoring requirements. Section 141.-
23, dealing with inorganic chemicsJ monitor-
ing requirements, received more comments
than any other section of the proposed regu-
lations. Altogether, there were over 300 dis-
crete comments on inorganic chemical moni-
toring, with the largest segment of the com-
ments being directed toward 5 141.29 (b),
the provision for increased monitoring when
7B% of «£m msaLmum oontnmlaiMit level to
The ooGoments on { 144-23(a) dealt mostly
with the time interval allowed for ootnpillcg
a historical reoord of water Quality, Most
comments contained Ute opinion that mora
time should be allowed for the "phasing ia"
of, particularly, the non-community water
systems. On the other hand, there were "com-
ments to the effect that too much time had
been allowed. There were a number of re-
quests that ana-cnmmunlty systems be ex-
empted from the lnorganio chemical moni-
toring requirements, on the basis thai mail-
mum contaminant levels are based oa life-
time chronic health esects, and that users
of non-community water systems are not ex-
posed for a lifetime. There also were com-
ments requesting that no distinction be
made between different types of water ays-
terns, such aa surface and ground. As noted
above, because MCL's for inorganic chemi-
cals have, in most cases, been based on
ohronlc health effects far lifetime exposures,
they will not be applied to non-community
systems. Therefore, S 141.23 has been re-
written to Indicate that, except for nitrates.
Inorganic chemicals monitoring will be re-
quired only for community water systems.
Virtually every comment on i 111.23(b)
expressed criticism of the concept of in-
creased monitoring when a contaminant
level reaches 76% of the maximum allowed.
Seasons given were that such monitoring Im-
poses "a safety factor on top of a safety
factor," that the State should determine
when increased monitoring frequency is de-
sirable, that analysis for some constituents
would be Impossible because of the limits of
detection, Uiat analytical costs would b»
prohibitive, that ground water contaminant
levels are not variable, and that the proposed
'monitoring frequency was too demanding.
Some commentors suggested that less fre-
quent monitoring be allowed when a con-
taminant level was below 60 of the MCL,
Section 141.33(b) wan written with the In-
tent that, when a contaminant level reached
75% of the MCL, monitoring frequency
would be increased bo that the supplier of
water would have an adequate warning of
possible or impending violation of the MCL.
By thus being forewarned, the supplier of
water could take corrective measures before
violation occurred. In Light of the comments
received, it has been concluded that although
such sampling may be a matter of good op-
erating practice, it is not appropriate for
inclusion in a primary drinking water regu-
lation for the reasons stated in the com-
ments, Therefore, the Administrator has
decided to withdraw ! 141.23(b), However,
the Administrator believes it would be pru-
dent for the operator of a community water
system to increase monitoring frequency for
a contaminant which appears to be approach-
ing the MCL, and for the States to direct
such increased monitoring when appropriate.
Comments on I 141.33(c) -were largely di-
rected toward the requirement that sampling
and analysis be repeated within 24 hours
after determination that an MCL has been
exceeded. It was felt that this did not allow
enough time, and In fact there was some
misunderstanding as to whether It was in-
tended that only the resampling be com-
pleted within 24 hours or that both resam-
pling and Preanalysis be • completed In this
time frame. Section 141.23(c) has been re-
written to indicate that when a sample result
does not comply with the MCL, the supplier
of water shall initiate three additional sam-
ples within one month. Since compliance
will be judged on the average of these four
samples initiated over a one-month period,
the requirement that the first check sample
be either completed or initiated within 34
hours is not justified.
Section 141.38(d) elicited a number of
comments in regard to the definition of m
•moving average," and there were general'
objections to the public notification provi-
sion. Ths opinions expressed were that ths
public should be notified only If the viola-
tion of as MCL involved an Imminent haaard
to health, or that emphasis should be plaoed
on correcting a problem rather than increas-
ing the monitoring frequency and notifying
the public. The rewording of section
141.23(c) to provide for a one-month «a*»
age has eliminated the need for paragraph
Id). The one-month average provides m Ian
complicated, more efficient Means of deter-
mining compliance,
ta regard to public notification of non-
compliance with an MCL. Section 1414(c)
of the Act requires that notice of such non-
compliance be conveyed to the public. Bw
nature of the corrective measures to be taken
are determined by the supplier of water and
the State. The comments on ! 141.33(e),
the special provisions for nitrate, w©T# -di-
rected toward the 34-hour re-analysis re-
quirement and the concept of the special
provision itself. Mast comments contained
the opinion that no re-analysis could b*"
performed In the time allotted, and other*
questioned the basis for singling out nitrate
for special consideration. Nitrate was singled
out for special consideration among tba In-
organic chemicals because of the acute tox-
icity of nitrate to infants. The, resampling
requirement has been rewritten for Unproved
The comments on 1141.23(f) dealt entirely
with' the suggestion that alternative analyti-
cal methods be allowed. Aa noted above, al-
ternative analytical techiques may be per-
mitted by the State if the substitute method
1s substantially equivalent to the techniques'
prescribed in this regulation, in both pre-
cision. and accuracy, as it relates to the deter-
mination of compliance with any maximum
contaminant level.
III. OaCAHie CHSMiesia
1. CCE. Section 141.12, maximum contami-
nant levels for organic chemicals, received
over 80 comments. Most of these comments
criticized the carbon chloroform estraat
(CCE) method for estimation of organic
chemical contamination. Criticisms of the
CCE requirement were based on cost, tack of
correlation with health efiects, inadequacy m
a measure of total organic chemical content,
inapplicability" to ground water, and lack
of supporting data. Some- comments sug-
gested an alternative surrogate for organic
chemical contamination, Including total
organic carbon and chemical oxygen demand.
Other comments concerning CCE wei« that It
be considered for inclusion in the Secondary
Drinking Water Regulations, that there be
provision for raising the MOL when "the
organlcs content of water Is shown to be
harmless, and that a treatment technique
be substituted for the MCL. Over twenty
comments requested that the CCE procedure
be dropped altogether. Three comments re-
quested that the limit be lowered.
The general problem of organic chemicals
In drinking water Is accorded top priority by
EPA. Concern over organic chemicals was one
of the principal reasons for passage of the
Safe Drinking Water Act. Surveys conducted
by EPA in recent months indicate that mas-
made organic chemicals acre present In small
amounts in water supplies in many parts of
the country, The Agency is committed to
using the regulatory tools provided by the
Act to deal with ths potential adverse health
effects of organic chemicals in drinking water.
The proposed use of a CPS maximum con-
taminant level was an attempt to deal with
gross organic pollution as soon as possible
pending the results of further research, «ur-

veys and the NAS study, COB was Initially
used as a means of taste and odor control,
A£ concern over adverse health affects of
organic chemicals grew, CCS was turned to
as a rough surrogate for organlcs to be used
as a health-based standard rather than as an
esthetic standard, Unfortunately, as more Is
learned about organic chemical pollution of
drinking water, CCE looks lest and less effec-
tive as a surrogate for harmful organlcs,
Th« principal difficult; with CCE Is that
it Include! only about one-tenth of the total
organic content of -the volume of water
sampled and it does not measure organic
compounds of greatest coacera, aucb as the
volatile halomethanes. Thus, a high CCE test
result does not necessarily mean that the
water tested may pose a hazard to health,
and a low CCE test result may be obtained
from water with a high level of potentially
harmful organic compounds. In short, there
Is no sound basis of correlation between CCE
test results and the level of harmful organic
chemicals In the water tested.
To establish a maximum contaminant level
under these circumstances would almost cer-
tainly do more harm than good, It could give
a false sense of security to persons served
by systems which are within the established
level and a false sense of alarm to persons
served by systems which exceed the level.
It also would divert resources and attention
from efforts to And more effective ways of
dealing with the organic chemical problem.
Total organic carbon (TOC) and chemical
oxygen demand (COD) are surrogates that
have been considered, but they have limita-
tions also, TOC has the advantage of being
quicker and cheaper (on a per sample basis)
than CCE. but the availability of sensitive
Instruments for this measurement is ques-
tionable, More Investigation of the signifi-
cance of any TOC number as a health effects
limit Is aS30 needed. COD Is easily deter-
mined with readily available laboratory
equipment, but COD is not limited to organic
compounds, and besides a COD number also
cannot be adequately related to health slc-
nlflcaaca at this time.
EPA Is diverting substantial resources to
research Into the health effects of specific
organic chemicals and groups of organic
chemicals. Also, It Is expected that the study
of the National Academy of. Sciences will
produce further data on health effects. How-
ever, In view of the significance of the poten-
tial health problem, It is not enough to wait
for this additional health effects data. EPA
therefore will undertake to identify one or
more surrogate tests for organic chemicals or
organic chemical groups, and will also study
in depth the presence of Bpeclfic organic
chemicals in drinking water supplies. It is
anticipated that this effort will result in
the development of an additional MCL or
MCL's for organic chemicals by amendment
of the Interim Primary Drinking .Water Reg-
ulations without having to wait for a more
complete resolution of the organic chemicals-
question in the Revised Regulations.
Accordingly, EPA is adopting regulations
on organic chemical monitoring, using the
authority of Sections 1445 and 1150 of the
Act, The regulations require that over 100
selected public water systems serving sub-
stantial populations collect samples of raw
and treated water for submission to EPA for
organlcs analysis. EPA will analyze the sam-
ples for a number of general organic parame-
ters, Including CCE, TOC (volatile and non-
volatile), NVOC, Total Organic Chlorine

mary enforcement responsibility as the period
when contamination by pesticides la moat
likely to occur. This takes into account the
fact that the level of pesticides In surface
waters varies oil a seasonal basin in relation
to agricultural uses of the pesticides. This
amendment will make monitoring lor pesti-
cides in drinking water more-effective.
Several comments criticised proposed
5 141.24(b), which would have required In-
creased monitoring when- the contaminant
level reaches 75% of the MCL, ThiB is basic-
ally the same question addressed above with
respect to'monitoring requirements tor In-
organic chemicals. Pot the same reasons, the
76% Increased monitoring requirement for
pesticides has been eliminated.
Other comments requested that EPA al-
low alternative analytical procedures. A new
I 141.27 has been added to provide that a
supplier of water may, with State approval,
employ an alternative analytical technique.
There appears to have been some misun-
derstanding regarding the role of the public
water system laboratory versus State or other
laboratories In performing analyses lor the
purpose of determining compliance with
thee# regulations, and In particular the
MCL's for pesticides. Although it is Intended
that the individual suppliers of water be re-
sponsible for the analyses. It waa not in-
tended thnt each supplier of water neces-
sarily posneaa the analytical capability to
perform the analyses himself It Is reasonable
to expect each supplier of water without Its
own laboratory facilities will collect and
transmit water samples to approved labora-
¦ It should be noted that with respect to
organic chemicals -and other contaminants,
'all MCL's and monitoring requirements In
these regulations are minimum requirements,
end It la Incumbent on the entity having
primary enforcement authority to require
additional monitoring and other require-
ments where appropriate.
IV. Tcusionr
¦ 1. Turtadity MCL's. About half of the more
than 180 comments on the MCL for tur-
' bid It y (I 141.14) contained a request that
turbidity be deleted from the Primary Drlnk-
: tag water Regulations or be relegated to the
".Secondary Drinking Water Regulations.
There were also requests that the MCL be
raised, that there be a limit of -6 turbidity
units ("TO") and a "goal" of 1 TO, and that
the MCL be' lowered. Other comments refer-
red to turbidity In sub-arctie waters, the
use of a two-level MCL for turbidity, and
the apparent encouragement of chlorlnation.
Hie Administrator has determined that
turbidity is Indeed appropriately classified
as a health limit, in that turbidity has a
marked effect on the bacteriological quality
of water, whether or not disinfection la pr»e-
' tleed.
As noted above, many comments ques-
tioned the need for a turbidity limit applic-
able to systems using only a ground water
source. In this regard the Administrator be-
lieves that In moat cases, turbidity Is not a
problem In properly developed wells. In some
cases, excess sand Is .Included In the water
pumped but this Is not a health related prob-
lem. In other cases dissolved iron present
precipitates upon oxidation. This also Is not
% health related problem. In some fractured
geologic formations and particularly .in lime-
stone formations, turbidity could be a peri-
odic problem because of a short retention
tlmea in the aquifer. In these cases the Stat#
Is encouraged to take appropriate action
in establishing a limit or treatment require-
Some comments questioned the proposal to
allow an MCL of 5 TO rather than l to la
case3 where the entity with primary enforce-
ment responsibility specifically authorized
th» higher MCL. The Administrator believes
this Is Justified on the basis that -not all
turbidity Is related to bacteriological quality.
Examples of Instances where the higher ttrr-
bidlty may be allowed are when Iron or other
minerals, or minute ice crystals in otherwise
satisfactory water, axe the cause of the tur-
bidity. Proving that a particular type of tur-
bidity does not Interfere with disinfection
or does not interfere with microbiological
determinations Is not always easy. One of the
best methods for proving the former is an ac-
cumulation of data showing good bacterio-
logical quality la the distribution system
over an extended period of time, even with
turbidity over I TU. A microbiologist can, by
various manipulative techniques, tell
whether or not turbidity Is interfering with
the conform test. No doubt a State may em-
ploy other means for determining when a
public water system has qualified for the
higher turbidity limit.
The proposed regulatiohs measured "the
turbidity MCL only on the basis of a monthly
average. The National Drinking Water Ad-
visory Council recommended that a supple-
mentary MCL be established to protect
against the appearance of a particularly high
turbidity level over a short period of time.
In accordance with the Council's recommen-
dation, I 141.13 has been amended to estab-
lish an MCL of 6 TU as an average of two
"consecutive dally samples, EPA agrees with
the Council that turbidity levels above 5 TU
cannot be Justified In surface waters for mora
than a one-day period.
That there is an Implied endorsement of
chlorlnation in these regulations cannot be
denied: The Administrator, recognizing chlo-
rlnation as being the only generally available
disinfectant In water treatment, has on sev-
eral occasions specifically endorsed chlorlna-
tion as a valuable public health measure.
Pending further research, the possible long-
term adverse effects of chlorlnation are in
most cases offset by the effectiveness of chlo-
rlr.a-.lon for preventing bacteriological con-
2. Turbidity Monitoring, There were over
120 comments on the turbidity monitoring
requirements (§141.22). Most of the com-
ments were directed toward the requirements
as they applied to water supplies using water
from underground sources, It was agreed that
turbidity In ground water need not be moni-
tored, and In fact there were a number of
comments suggesting that turbidity monitor-
ing be deleted altogether. There were com-
ments that the sampling was too frequent,
and comment* that in some circumstances
the sampling was too Infrequent. The ques-
tion of cost was brought up In connection
with sampling frequency. There also were re-
quests for clarification of the entire section,
with particular emphasis on defining an "en-
try point" to a distribution system.
It waa the intent of the Administrator that
public non-community water systems using
ground water be exempted from the turbidity
monitoring provisions. Unfortunately, how-
ever, the omission of commas la 5 141.22(c)
made It appear that only community systems
¦using ground water were required to moni-
tor for turbidity. The section has been writ-
ten so that the turbidity monitoring require-
ments apply only to water systems using sur-
face water sources. Also, for non-community
systems using surface water, the regulations
have been modified to require that the tur-
bidity monitoring must be initiated within
2 years of the effective date.
The measurement of turbidity at the entry
point to.the distribution system, rather than
at the consumer's tap, can be justified on at
least two bases. First, since turbidity can be
controlled only by water treatment processes.
It is most appropriately measured immedi-
ately after the water has been treated, and
before the measurement l:« affected by scale,
sediment or other materials present In. pipe-
lines. Second, since one of the principal
purposes for limiting turbidity Ifl the fact
that turbidity Interferes with disinfection,
and since disinfection is effected at the treat-
ment plant, turbidity at the consumer's tap
is not an adequate reflection of conditions
where disinfection is taking ¦ place.
Comments suggesting an increased sam-
pling frequency for turbidity in effect were
suggesting operational monitoring desirable
in specific cases rather than a' frequency
which. Is practical when generally applied
to thousands of public water systems. It
should be ralterated that these regulations
contain only minimum requirements, aod
that more frequent monitoring can be re-
quired by SPA or the States In appprorlate
cases. Furthermore; there is nothing la these
regulations to deter a supplier of water from
more frequent turbidity monitoring as an
operational guide.
Other comments on turbidity monitoring
stated that the proposed requirements were
too expensive, However, the cost and effort
Involved in measuring turbidity are-not ex-
cessive. "This la one parameter which can be,
and in fact must be, measured by the individ-
ual suppliers of water. Almost anyone can'
learn to take turbidity measurements, and
only a few seconds are required for each
measurement, The only cost Is In the pur-
chase of a turbidimeter, which lasts for many
In order to take Into account the fact that
turbidity measurements la most cases will
not be taken by trained"laboratory tebh-
nlclans and that erroneous high readings
can be obtained by careless handling of the
teat, 5 141.22(b) has been amended to pro-
vide that If the Initial -dally 'sample appears
to exceed the maximum allowable limit but
a repeat sample shows a lower turbidity, the
results of the repeat sample shall be used
rather than the results of the Initial sample.
Because turbidity Is closely Interrelated
with filtration and disinfection., sampling
is to be done «t "a representative entry
polnt(3) to the water distribution system."
This means at a point between the filters
and the mains. A clear well would be appro-
priate, aa would be a point between a pump
discharge and the mains tf there are no Al-
tera. In the event that there are several
"entry points," such as would be the case
when there are several well pumps, a sam-
pling point common to all pump dis-
charges -would obviate the necessity to sample'
at each pump discharge. If there la a ques-
tion as to whether or not a particular sam-
pling point were "representative" of the
water being delivered to the distribution
system, the State would make the decision.
Alternative analytical- procedures, such as
continuous .turbidity monitors, may'be"used
at the discretion of the State.
V. Microbiological Limits
1. CaUformi Limits and Standard Plate
Count. There were almost' 140 commenta on
i 141.16, Maximum Microbiological Contami-
nant Levels, of which about half were
directed toward { 141.16(b), the standard
plant count <"SPC"). Moat of the com-
ments on i 141.16(a), coll-fcrrm limits, were
general In nature, covering such points as
clarification of the language, use of alterna-
tive Indicator organisms, raising or lower-
ing the limits, averaging of results, aud. the
assignment of responsibility for performing
the tests. Nearly all the' comments oa the
BPO expressed opposition to the imposition
of a maximum contaminant level. Opposition
waa based on the lack of health significance
of the SPC and the unfavorable cost-benefit
-- *' 87

Section 141.15(B) has been rewritten for
clarification. Tie Administrator believes the
conform group of organisms are the beet In-
dicators of bacteriological quality of drink-
ing water, although of course research Into
possible alternative Indicators Ss ongoing.
The Administrator also believes the maxi-
mum contaminant levels lor conform or-
ganisms are adequate to protect the health
of consumers. Other limits for bacteriologi-
cal quality, such as those in the World
Health Organization Drinking Water Stand-
ards, may appear to ba more stringent and
thus wore protective of health, but It must
he remembered that WHO standards are
merely guidelines, not enforceable regula-
tions. It should also Be remembered that the
currently proposed regulations contain mini,
mum standards of quality, and that lower
levels of contaminants should be attained
when feasible. Because of the effect a single
sample may have on a monthly average, par-
ticularly when only a few samples are ex-
amined per month, quarterly averaging will
be allowed for those public water systems
serving populations of 3300 or less.
Although the Administrator has evidence
that the Standard Plate Count does have
health significance, and In addition is a valid
Indicator of bacteriological quality of drink-
ing water, the Administrator has deleted
1141.16(b). Because the coliform limit pro-
vides adequate protection against microbio-
logical contamination, the cost of an SPO
requirement cannot be Justified. However
the Administrator recommends that the SPo
measurement be applied Judiciously wher-
ever indicated, if only as "an operational tool,
In conjunction with the coliform test.
2. Chlorine Residual Substitution. There
were over 170 comments on 8141.18, the
chlorine residual substitution provision. The
comments represented overwhelming oppo-
sition to total substitution with concomitant
suspension of the coliform test. There wero
also comments on the analytical procedure,
free chlorine residual versus' combined resid-
ual, and particular opposition to the con-
cept of allowing substitution In the smaller
communities. In the latter case, it was stated
that a small community would not have a
water system operator of sufficient.skill or
dedication to monitor chlorine residuals ac.
curately or faithfully. There were several
questions regarding the different chlorine
residuals speclfled in IS 141.13(a) and 141.16
(h). Some believed the residual should be
raised, while others believed the lower resid-
uals should be permitted.
The chlorine residual substitution provi-
sion was inserted so that in those "com-
munities where chlorlnatlon. Is practiced,
some economic benefits might be realized by
the deletion of part of the conform testing
requirements without affecting the health
protection provided. In the smallest com-
munities, total substitution of chlorine re-
sidual testing would result in a significant
economic benefit, since it Is in these com-
munities that the maintenance of adequate
water quality has the highest per capita
cost. The Administrator believed that the
maintenance of an adequate chlorine resid-
ual In a distribution system throughout a
month .was at least equivalent, in health
safety terms, to Isolated coliform tests. In
the event that total substitution had been
allowed by the State,. the slightly higher
chlorine residual provided a greater factor of
It Is true that a chlorine residual alone
does not guarantee the absence of pathogenic
bacteria. It is also true that a negative con-
form test does not always guarantee the ab-
sence of pathogenic bacteria. However, the
Administrator concedes that, because of
questionable reliance on unskilled operators
In the smallest communities, it would not be
prudent to permit 100% substitution of chlo-
rine residual testing for coliform tests to
those cases. For this reason, proposed ; 141.-
10(b) has been deleted. However, 76% substi-
tution will be permitted where specifically
authorized by the eatlty with primary en-
forcement authority.
The analytical method specified for chlo-
rine residual testing led to some misunder-
standing. The DPD method, as described to
"Standard Methods of Examination of Water
and Wastewater," appears to be an Involved
and sophisticated procedure, it waa specified
primarily on the basis of accuracy and sensi-
tivity, particularly when compared with the
o-toUdlnc procedure In common use. The
latter has been shown to be inaccurate and
unreliable, but remains popular because of
Its simplicity and the ready availability of
field test kits. What is not known, apparently,
Is that the DPD test 1s almost aa simple and
is also available In reasonably priced fleli
test kits.
Chlorine substitution has been specified,
rather tban "disinfection substitution," sim-
ply because there is no- other disinfection
procedure of comparable sifaty and reliabil-
ity. lodlnatlon has been suggested, but iodine
presents a health risk to some persons.
3. Microbiological Monitoring. There were
over 250 comments on ( 141.21, microbiologi-
cal contaminant monitoring requirements, of
which over 70 comments were directed toward
8 141.31(g), the standard plate count moni-
toring requirement. Although both increased
and decreased sampling frequencies for
conforms were requested, by far the greater
number of comments expressed the opinion
that the requirements of this section were
unreasonably burdensome, particularly for
the' smaller communities and non-commu-
nity public water systems. There were also
numerous requests for clarification or modl-
fleatlon of the coliform monitoring require-
ments. such as requests to modify the time
for resampling, requests to permit exclusion
of sampling points which have been shown
to be contaminated, and requests to permit
discarding positive bacteriological sampling
results for which the check sample results
are negative. In regard to S 141.31(g), the
standard plate count monitoring require-
ment, most comments reflected the objec-
tions to the parameter itself rather than ob-
jections to the frequency of monitoring.
Considerable attention, has been given to
the sanitary surveys and monitoring fre-
quency tor conforms, particularly In the case
of small community systems or non-commu-
nity systems. The concept of a sanitary sur-
vey, expressed in a number of comments,
can be considered as a factor In determining
the sampling frequency for a particular sys-
tem. The practicality of sanitary surveys, at
annual or even less frequent Intervals, versus
the collection and analysis of two water
samples per month, must be carefully con-
sidered on both economic and manpower re-
quirements. It has been estimated that there
ore 200,00 non-community water systems In
this country, but from the information sup-
plied In the comments received it Is evident
that this number may be too conservative.
An adequate sanitary survey of each of these
systems In one year would create a severe
strain on the skilled manpower necessary.
The consensus of opinion from the States
is that, in the event a sanitary survey be-
comes acceptable for establishing coliform
sampling frequency for any segment of pub-
lic water systems, a- priority scheduling of
surveys will be established, with populations
at risk and known trouble spots being factors
to consider. With such priorities, It la evi-
dent that the non-community systems, serv-
ing small population groups and delivering
water on which there is no past record, will
be last to receive attention. For this reason,
among others, the paragraph on coliform
monitoring, 5141.21(a), has been re-written
to establish a minimum sampling frequency
of one per calendar quarter for non-commu-
nity systems. A sanitary survey can be used
as a basis for modifying the sampling fre-
quency. For the smaller community public
water systems, a new population range has
been delineated, with an accompanying re-
duction la coliform sampling frequency. In
this range • (25-1,000 persons served) en#
sample per month la the minimum, although
the state may, based on a sanitary survey
verifying certain conditions, reduce the sam-
pling frequency, except that In no case shall
It be reduced to leas than one per quarter.
In addition, the paragraph has been re-writ-
ten to clarify the intent and to spell out
more precisely the means by which compli-
ance or noa-compilance is determined.
Aa effort has also been made to clarify
the samples that ahould be Included and
excluded among those used to calculate com-
pliance. In this regard, a paragraph has been
added on "special purpose samples", to define
those used to check such operations as pipe
disinfection procedures.
For non-community systems. In order to
ease the laboratory work load, and provide
a phased approach, the bacteriological mon-
itoring requirement must be implemented
within 2 years after the effective date of
the regulations. This provides & 2 year period
for'the suppliers. State agencies, and labora-
tories to prepare for the greatly increased
number of samples to be analyzed.
In response to the request to permit Ut(
elimination from future sampling of those
points that have a history of questlonabll
water quality, the wording has been modi-
fied to state that any sampling point at
which check samples have been required
may not be eliminated from future sampling
without approval of the State.
Concern has been expressed that in some
cases, because of either a sampling or a
laboratory. error, a microbiological analysis
could result In an erroneously large count.
The regulations require that this result be
included among those samples used In cal-
culating the average monthly coliform bac-
teria density, even though the subsequent
check samples may have been all negative.
This high count could cause the supplier to
fall the monthly average and thus require
that he notify the public.
The Administrator understands this prob-
lem, but cannot agree that'the one "bad"
sample should not be included la calculat-
ing the average. The reason Is that there Is
no way to confirm that the bacteriological
result of a sample collected In the past was
due to sampling or analytical error. It can-
not be accomplished, for example, by col-
lecting a check sample, which by tha length
of the standard test, would Have to be col-
lected at least one day after the original
sample. The check sample would not neces-
sarily reflect the bacterial situation of the
previous day. The only way to confirm bac-
terial sampling results axe to collect and
analyze samples in duplicate or triplicate.
Since there Is no provision for discarding
or adjusting for occasional spurious results
from sampling or analytical error, EPA rec-
ommends that for positive bacterial analyses
standard analytical verification methods be
used to verify analytically that coliform bac-
teria are present.
As stated earlier, the standard plate count
requirement has been deleted, although it is
recommended that the parameter bs em-
ployed as conditions warrant.
There were over 100 comments on I 141.27
dealing with laboratory certification. In gen-
eral, there was agreement with the con-

eept of laboratory certification, although
there were a few request* for clarification of
tha role of the certifying authority. Most of
the comments contained objections to the
concept or requiring turbidity and chlorine
residual tests to be performed by certified
laboratories. The remaining comments ad-
dressed the cost of certification, the need for
time to get labs certified, and the scarcity
of qualified laboratories.
It wu the Intent of the Administrator
that EPA would certify at least one labora-
tory lxi each State with other laboratories to
• be certified by the State laboratory or
.laboratories qualified to perform this func-
' "tlon. Because of the transient nature of tur-
. bldity and chlorine residual values, H la not
possible for a public water syBtem to collect
samples and transmit them to » central
laboratory for determination of these param-
eters. It W«a the Intent of the Administra-
tor that the individual operators of public
water systems perform their own turbidity
and chlorine residual analyses. It would
seem advisable, however, that such operators
to certified, approved, or at least minimally
trained to perform the analytical tasks be-
fore a State could accept their analytical
determinations as having enough validity
for decisions regarding compliance or non-
compliance to be made.
VII. Reporting and Pubmc .Notification
1.	Reporting. There were over 200 com-
ments on } 141.31, dealing with reporting
requirements, but only three basic criticisms;
the, reporting requirement should be limited
to those situations which are essential to
enforcement of the regulations; the section
needs clarification; and the Institution ot
reporting requirements makes compliance
with tha regulations either difficult or im-
possible. Minor comments included requests
for changes In the 36-hour and 40-day
reporting requirements, requests for a cor-
rective action requirement rather than a
reporting requirement, and requests that
Federal agencies report to the States rather
than to EPA.
Section 1413 of the Public Health Service
Act deals with the role of the States In
Implementing and enforcing drinking water
regulations. Section 1414 of the Act spells out
actions to be taken if a State fall3 to assure
enforcement of drinking water regulations.
A State could not effectively comply with the
provisions of the30 sections without receiving
regular reports from every public water sys-
tem within its jurisdiction. Monitoring fre-
quencies have been established, and II only
violations of maximum contaminant levels
were reported the State would not know
whether or not monitoring frequencies had
been adhered to. Thus all activities of a sup-
plier of water in connection with these regu-
lations are essential to enforcement of the
regulations and must be reported to the
It is apparent from Section 1447 of the
Public Health Service Act and the legislative
history of the Safe Drinking Water Act that
Federal agencies are to be treated exactly
like any other owner or operator of a public
water system, except In cases Involving na-
tional security, Therefore, the Administrator
believes that It would be contrary to tha
Intent of the Act to require Federal agencies
to report only to EPA and not to States with
primary enforcement responsibility. In tha
revision of 5 141,31 of these regulations, no
exemption for Federal agencies from the pro-
visions of the regulations will be specified.
2,	Public Notification, section 141.32, the
public notification provision, received a large
number of comments, of the more than 300
comments, only two approved of this section
as written. Two additional comments con-
tained suggestions for modification, such as,
for example, to require a second notice to tell
the public that the condition previously re-
ported had now been corrected. Every other
comment expressed opposition to public
notification, either on the basis of disagree-
ment with the concept, on the basis of in-
approprifteness for some types of water sys-
tems, or on the basis ot some type of in-
equity. Most frequently heard comments
were: the State should have the authority
to notify consumers only lr there is an Im-
mediate and significant threat to public
health.; scare tactics will lead to public dis-
regard; notification by radio and TV within
38 hours is an ' unreasonable requirement;
notification of the entire public Is unreason-
able when only a portion of the public Is
involved; and notification by means of water
bills la unacceptable. One of the more con-
structive comments was that, while the con-
cept at public notification was opposed, the
supplier of water should be given the op-
portunity to explain the deficiency.- «
To explain tha Intent of Congress In re-
quiring public notification, the following la
quoted from House Report No. 63-1185;
"The purpose of this notice requirement Is
to educate the public as to the extent to
which public water systems serving them are
performing Inadequately la light of the ob-
jectives and requirements ot this bill. Such
public education la deemed essential by the
Committee In order to develop, public aware-
ness of the problems facing public water
systems, to encourage a willingness to sup-
port greater expenditure at all levels of gov-
ernment jo assist in solving these problems,
and to advice the public of potential or
actual health hazards,"
The Administrator agrees that the supplier
should be Kivi-r, the opportunity to explain
the deficiency. It was not the intent of Con-
gress, that such notices would be merely a
fist statement that tha water system had
failed to meet the requirements of the Regu-
lations. To quote the House Report further:
"the Committee expects that the Adminis-
trator's regulations would permit public
water systems to give fair explanation of the
significance or seriousness for the public
health of any violation, failure, exemption
or variance. These regulations should also
permit fair explanation of steps taken by
the system to correct any problem."
The wording has therefore been modified
to permit that the supplier may use the
notice to explain the significance or serious-
ness of the violation, to include the results
of additional (subsequent) sampling, and to
indicate preventative measures that should
be taken by the public.
As to the unreasonableness of allowing
only 36 hours prior to radio and TV notifica-
tion, this wording has been modified to read
48 hours and the Administrator believes that
this Is adequate time to prepare such noti-
fication when an MCL is violated.
Time requirements for notification In
newspapers has been established. The regu-
lations require that the failure of any MCL
shall be published In a daily newspaper or
newspapers of general circulation In the
area served by the system, on not less than
three consecutive days, and that such notifi-
cation Is to be completed within "seven days
after the supplier learns of the failure. The
notice shall be provided to radio- and tele-
vision stations within 48 hours after he learns
of the failure.
Public notice for other failures of tbe reg-
ulations, such m failure to comply with test-
ing procedures, failure to comply with moni-
toring requirements, and failure to comply
with a schedule prescribed pursuant to a
variance or exemption, is to be made by In-
cluding a notice with the water bills, within
at least three months after the supplier learns
of the failure, In the event water bills are not
issued, there Is a provision for using another
form of direct mall.
The provision for mailing notices responds
at least In part to the comment that the
notice should not be made to the entire
public but only to the portion of the public
¦using the water. Otherwise, It is true that a
notic® given la a newspaper of general dis«"
tribution, or a radio or television broadoast/
will reach more' people than those affected
by a particular public water sptem.
• There is no way that this can be avoided,
but there is nothing in the regulations which
would prevent the notloa from specifying
which person or which area need be con-
cerned about tha notloa,
The Administrator agrees that the pro-
posed public notice provisions are Inappro-
priate for non-community water systems. No-
tices In the local media and in water bills
will not have the Intended effect with these
systems serving transients or "Intermittent
users, Therefore, S 141,32 has been revised to
Include a provision for other types of notifi-
cation, subject to approval by the State, for
non-community water systems. Envisioned
here axe such types of notification as a
poster or sign near the drinking fountain
of a facility serving the travelling public, or
a handbill distributed to factory workers.
vin. Economic Considerations
There were over 100 comments on the eco-
nomic aspects of the regulations. The two
most frequent comments were that the esti-
mates in the preamble were much too low,
and that the economic impact on the smaller
water utilities would be severe, The correc-
tive measure suggested in most cases was
that EPA should give grants to the public
water systems or should provide funds to the
States to pay for monitoring. In general, the
comments contained criticisms of the regu-
lations In that they were termed "not cost
It was the intent of Congress that the hulk
of the costs associated with the Safe Drink-
ing Water Act would be borne by the Indi-
vidual public water systems and thua the
consumers. Of all the comments on the cost
of a program to Improve the quality of drink-
ing water, it Is noteworthy that only one'
comment stressed the benefits to those con-
There la no doubt that money will be spent
for Increased monitoring. This la particularly
true for the smaller water systems, where In
the-past practically no monitoring has been
performed. These very small water systems
are the ones which most heed improvement,
bo it can be expected that the costs will ba
proportionately higher for the small systems
when compared with larger systems. On a per
capita basis, since so few customers are in-
volved, the costs will be disproportionately
higher for the smaller systems. Congress did
not intend that the monitoring costs for
these systems would be subsidised. Rather,
Congress hoped that many small systems
would be consolidated Into larger systems, so
that the costs would be shared by a larger
number of consumers, and so that Improved
drinking .water quality would more easily
be attained,
A cost and economic analysis of the moni-
toring requirements are attached as Ap-
pendix B.
IX. Other Comments
1. Siting. Of the more than 70 comments
on 5 141.41, siting requirements, most either
wanted the section deleted or else clarified
in some way. The criticisms were that the re-
quirements for siting were not realistic, that
the terms used needed definitions, that State

approval lis granted before a change la a
water system'ba made, or that State approval
Is already required la the clrcum&tancea. The
limitation regarding the "100-year flood" was
criticized- on the baste that water Intakes
(for surface water soureea) must be In the
floodplaln. Suggsetlona included: use the
wonls "geological hazards, and man-made
disaatera;" add the phrase "avoid causing ad-
verse environmental impacts;" and limit the
provisions to "ground level or underground
storage facilities, vertical wells of a system
which has no filtration or any other treat-
meat facilities."
It should be pointed out that the section
on sttlng requirements In these regulations ta
flexible, In that the phrese "to the extent
practicable" allows considerable leeway.
Then minimum siting requirements were In-
cluded on the basis olsectfcju l«01 (1) (D) ot
the Public Health Service Act, which states;
"The term *prl«*ry drinking water regula-
tion* means a regulation which contains
• • • requirements as to (11) siting fox new
facilities for public water systems." Obvi-
ously, com clarification of even these mini-
mal requirements Is e&lled for, so the section
Has been revised. In accordance with Congres-
sional Intent, the revised version mates clear
that all final siting decisions are to be made
at the State tad. local government level.
a. Effective date. There were only three
comments on 1141.51, the effective date of
these regulations. All of these comments con-
tained the request that more time be allowed
for water systems, particularly those of small
communities, to come into compliance.
The effective date of these regulations was
established by section 141.12(a)(8) of the
Public Health Service Act, which provides
that, "The Interim primary regulations first
promulgated under paragraph .(1) shall take
affect eighteen months after the date of ttielr
promulgation." The Administrator ¦ believes
that, by scheduling the monitoring require-
ments la several phases, ample consideration
has been given to small systems. Variances
and exemptions will be available in appropri-
ate cases.
3.	Radionuclides. There were approximate-
ly 50 comments relating to maximum con-
taminant levels for radionuclides, However,
EPA only proposed MCI/s for radionuclides
on August 14, 1976. 40 PR 34334. Comments
on radionuclides will be taken into account
In that rulemaking proceeding.
4,	Water treatment chemicals. Ten com-
ments addressed chemical requirements In
connection with the proposed regulations.
The comments stated that certain chemicals,
particularly"activated carbon and filter grade-
alum, are In short supply.
It is acknowledged that bq Increase In the
extent of water treatment will cause an in-
creased demand for water treatment chemi-
cals. If a particular treatment technique were
to be specified, the demand for any chemical
Involved In that treatment technique could
Increase dramatically, since no treatment In
lieu of a monitoring requirement was speci-
fied In these regulations, the problem has
not surfaced as yet. Before specifying any
treatment technique, the Administrator will
Investigate both the availability of the neces-
sary chemicals and the costs associated with
that treatment technique. Naturally, the
effect of an Increased demand for a particular
chemical on the coat ol that chemical will
also be investigated. Because of the phasing
of the provisions of the Safe Drinking Water
Act, and because there Is currently no short-
age of raw materials for the production of
water treatment chemicals, it can be ex-
pected that ample quantities of tbeae chem-
Icalu will be available, for conventional wa-
ter treatment when they are needed.
S. Treatment technkfuea. Oa the subject
of treatment techniques or treatment tech-
nology, 30 comments contained criticisms or
suggestions It was noted that no treatment
techniques were specified to lieu of MCL'a,
and almost unanimous support for this ap-
proach was expressed. On the other hand, 16
was suggested that Information on treatment
technology to remove certain contaminants
be supplied.
While no treatment technique requirement
was Included In these regulations, the Ad-
ministrator may specify such techniques In ¦
revised regulations If warranted. The Admin-
istrator believes, however, that It Is always
preferable to specify monitoring require-
ments If at all possible, beoause of the un-
certainties involved la a treatment
technique. Although a treatment technique
may appear to be capable of removing a
particular contaminant, based on laboratory
or pilot plant .studies. In actual water plant
operation such removal may not always
occur. Without monitoring, the adequacy of
the treatment technique cannot be ascer-
tained. As for technology' for the operation
of a conventional water treatment plant, op-
eration and maintenance regulations are to
be published separately. Techniques to be
used for the. removal of specific contami-
nants are the sutlject of ongoing research,
a. Miscellaneous. Comments -not classified
elsewhere addressed a cumber of miscella-
neous topics. Including the following;
typographical errors, regulations for the
quality of Intake water, control of pollutants
at the source rather than ta drinking water,
training of water plant operators and the
encouragement of young people to eater
the water treatment field, control of water-
sheds as a means lor Improving the drinking
water quality, amending the regulations to
eliminate systems serving less than 200 peo-
ple, setting of priorities according to size
and type of system when applying the regu-
lations, regulations for Interconnections of
¦supplies, provision of technical support by
the Environmental Protection Agency Be-
gional Offices, and the development of a pol-
icy on carcinogens as an aid to standard
Appendix B—Cost and Economic Analysis
Executive . Swmmabt 1
1.0 , Safe Drinking Water Act aj 1S74. The
objective of the Safe Dranking Water Act,
(Pub. b. 63-623) la to establish standards'
which will provide for safe drinking water
supplies throughout the On!ted States. To
achieve this objective the Congress author-
ized the Environmental Protection Agency to
establish national drinking water regula-
tions. In addition, the Act provides a mech-
anism for the Individual States to assume
the primary responsibility for enforcing the
regulations, providing general supervisory
aid to the public water systems, and in-
specting public water supplies.
The purpose of the legislation Is to assure
that water supply systems serving the public
meet minimum national standards for the
protection of public health. Prior to passage
of the Act. the Environmental Protection
Agency was authorized to prescribe Federal
1 This summary Is based oil a detailed and
comprehensive study prepared for EPA by
¦Energy Resources Company of Cambridge,
Massachusetts, titled, "Economic Evaluation
of the Interim Primary Drinking Water Reg-
ulations" (October 197S),
drinking water standards applicable only to
water supplies used by interstate carriers.
Furthermore, these standards could only bs
enforced with respect to contaminants capa-
ble of causing communicable diseases. In.
contrast, the Safe Drinking Water Act au-
thorized the Environmental Protection
Agency to establish regulations to (1) pro-
tect public watar systems from all harmful
contaminants; (2) protect underground
sources of drinking water; and (3) promote
a joint Federal-State system for assuring
compliance with these regulations.
X.X National interim, primary drinking.
Water regulations. The EPA published Its
Proposed National Interim Primary Drinking
Water Regulations In the Pede*aj. Rkoistkb.
March 14, 1375. The EPA held four publlfi
hearings and received several thousand
pages of public" comments on the pro-
posed regulations. Based upon its review of
the comments, the EPA revised the proposed
regulations for final publication. The major
provisions of the Interim Primary Printing
Water Regulations are:
1. Maximum contaminant levels for cer-
tain chemical, biological, and physical con-
taminants are established;
a. Monitoring frequencies to determine
that contaminant levels assure compliance
are established; and
8. A methodology to notify.consumers of
variances, exemptions, and non-compltonce
with standards Is set forth.
1,2 The Water supply Industry,.
1.2.1 Public Water Systems. The Safe
Drinking Water Act of 1974 covers publia
water systems that regularly serve an aver-
age of 25 people or have at a minimum 15
service connections. Systems that serve the
travelling public are considered public water
systems -under the Act. EPA currently .esti-
mates there are 240,000 public water systems
that will - bs subject to the regulatory re-
quirements developed under the Act.
The Interim Primary Drinking'' Water
Regulations categorize public systems as
community and non-community systems. A
community system Is defined as a public
system which serves at least 16 service con-
nections .used by year-round residents of
regularly serves at least 35 year-round resi-
dents. The non-community system category
Includes those systems which serve a tran-
sient population. At the present time the
distribution between the two classes of pub-
lic systems is estimated as follows:
Community systems—	 40,000
Non-community systems	 200, 000
Total 			240,000
Based on the data contained la the on-
going EPA public water supply Inventory,
there are approximately 117 million persons
served by community water systems. Table
1-1 shows the distribution of community
systems by population served. Most of the
community water systems are small in slae.
Over 90 percent of the nation*# supplies are
In the under 10,000 persona-served category
but they provide water to less than 26 per-
cent of the total population served by com-
munity systems.
While all public systems do not treat all
of the water they supply to their customer*,
they do employ a variety at treatment proc-
esses. The current EPA Inventory of Public
Water Supplies Indicates that the most
prevalent treatment processes are used to
control bacteriological contamination and
turbidity. The percentage of systems em-
ploying the various treatment processes Is
presented in Table 2-2.

Tablb 1-1.—Distribution of community teaier syalemi
Syttem sIm (persons eervrf)
Number of Total popula- Percent of
water systems uon served total population
(In thousands) served
»to*	——			 7,008	420-
10010 9,906.	 80,150	M,81«
10,000 tow,999					 2,599	81,423
100,000 ml) over					243	78,800
Total	_ 40, GOO	177,488
Source: EPA Inventory of Public Wttar Supplies (Jul? 1971).
T«* 1-2.—Treatment PaacssMa Emfujteb
¦t comxtohy Waxes arwrsMM
Treatment:	Percent (r)
Aeration	i			.	0,0
Prechlorination 			7. 8
Oosgulatlon 	.	11.3
Sedlmenatlon 	•_	8. 9
Filtration 		12.8
Softening ....		4.8
Taste and odor control		8.4
Iron removal..	,				6.7
Ammoniatlon .....					0.9
Fluoride adjustment		0.6
Dlal&le^tlon ....			36. 3
i Percentages do not total 100 percent
since many systeoRs have multiple treat-
ments, or no treatment.
Source: EPA Inventory of Public Water
Supplies (July 1978).
Community water systems may be pub.
llely or privately owned. The majority, 68
percent, of the 40,000 community water sup-
plies we publicly owned and these systems
supply 88 percent of the total drinking water
As Indicated earlier, It is estimated that
there are approximately 200,000 public non-
community water systems. Most of these
systems are privately owned. Non-commu-
nity systems are found at service stations,
motels, restaurants, rest areas, camp grounds,
State parks, beaches, national parks, na-
tional forests, dams, reservoirs, and other
locations frequented by the travelling pub-
lic. Some EChools and Industries are also In-
cluded In this category. Data on these "sys-
tems are very sparse, and only rough cost
estimates can be made.
The portion of the water supply industry
considered here includes only those systems
which primarily supply water for residential,
commercial, Industrial and municipal use.
An approximate allocation of water use by
various categories of users is shown in Table
1-3. As might be expected most of the water
delivered, 83 percent, is for residential put-
poses. The second largest use. Industrial,
consumes ai percent.
Tilts 1-3.—COMMOTICT W&TW Bmvht Oil
Type of use;	o} total
Residential 			OS
Commercial	.... 11
Industrial	 St
Municipal. 	...	....... S
Total 			100
Source: U.S. Qeoiogic&l Survey Data (1972)
1.3 Costs to meet the interim primary
drinking water refutations.
1.3.1 Monitoring coats. The Implementa-
tion of- the Interim Primary Drinking Water
Regulations will require oil public water sys-
tems to initiate a monitoring program to
determine that the maximum contaminant
level requirements of the regulations are not
exceeded in finished drinking water. The
costs associated with this monitoring activ-
ity are a function of system size, water
source, and classification (community vs.
There are two classes of monitoring costs,
routine monitoring costs and non-compli-
ance monitoring costs, imposed by the In-
terim regulations. Routine monitoring costs
are those Incurred In meeting the sampling
requirements of the Interim Primary Drink-
ing Water Regulations, to determine compli-
ance with the regulations. Non-compliance
monitoring costs are those which are In-
curred when additional sampling must be
made If routine monitoring results Indicate
that a system Is not In compliance with one
or more maximum contaminant limit.
The Interim Primary Drinking Water
Regulations call for the monitoring of four
classes of contamination: inorganic, organic,
microbiological, and turbidity. The routine
monitoring frequencies for community ana
non-community systems are shown in
Tables 1-4 and 1-8.
1-4.—Monitoring requirements: Cotntnu-nily supplies; interim primary drirtking
water regulations'
Component	System type	Deadline for Initial sampling Testing frequency
after effective date
Coliterm	 Ground and surface.		1M	:	Monthly.1
Inorganic chemicals	Surface	„	 i yr					Annually.
0 round...;	2 yr				 Every Syr.
Organic chemicals	 Surface	l jt	 (>).
Ground	 As specified by the State	As specified by the State.
Turbidity	 Burke®..	1 d	Daily.
1 BuppUea must collect minimum required samples during each month after effective date. The number Maaaplsi
varies with the system site (rem 1 tn 500 samples per month.
. The Stele may reduce the sampling frequency based on a sanitary survey of a system that tervea lets than 1,009
persons From a groundwater source, aicept that In no ease sballlt be reduced to lesa than one per quarter.
¦ The analyses shall be repeated at internals specified by the State but In no event leas fraquentlythan at J-yf

Table 1-5,—Monitoring requirements: Nffncommunity supplies; tnierim primary drinking
aater regulations
C«znponang	Bffttra l> ;.irtae« and grou-d			do		—	Detaniiined bj> toe 8terte. .
auiES ft&euiAmoMS
4, Estimates of the number of MCL viola-
tions were based on 1669 Community Water
Supply Study, exempt for mercury. Mercury
violation* were based on recent EPA studies.
The national treatment costs for fmblto
water RyB tenia are summarized In Table l-T.
The majority of fonts, if ell systems elect to
treat for contaminant Eolations, -will be In-
curred ta order to neat the turbidity and in-
organic requirements of the interim regula-
tioaa. Ranges were developed tar capital-cost®
only, Thtt range ta bBsed on making two as-
sumptions for dally flow. If a system were
required to install tfeatspent. It would have
to consider sizing their new components to
reflect average dally flow conditions or maxi-
mum dally Sow conditions In eases whet®
system storage to not adequate. Wbatevgi
sizing option a system selected it la unlikely
that significant ackStttsnal operatic© aofi
mMntenancs espenaes would result.
Table 1—7.—National casts of treating eontaminanti in drinking water
millions of dollajsl
Treatment teobcotaar
Capital costs Annual opMBtfcm
and mHatena&s
Coajaonity >ysteau:
Clsrifkatjon						 Puibldlty...
Chlori nation...
I011 Eielmnm.
Activated «lurrin».	 As, fluoride
pH Ooatrel				 Fb.
Ba, Cr, Cd, N0», Hg, 8e.
IT- 71
H»- 987
si- m
5-" 4
Non-community ayttems:
ClarlSntJon	Tnrbldlty.,
OhloHoatloo^				Conform...
Nors.—Totals ma; mit add due to rounding.
1.4 Economic impact of the interim pri-
mary drinking water regulation*
The expenditures required to comply wltti
tie Interim • Primary Regulations will have
an impact on all water users served by public
water supplies covered by the safe Drimiing
Water Act. All persona served by these sys-
tems will feel the Impact at monitoring coats
toBome extent. However, tbe most noticeable
Impact of the regulations will be on users
of public water systems that do not meet the
MCL requirements of the regulations,
As estimate of tbe total annual coats of
capital, operation and maintenance, and
monitoring necessary to comply with the
Regulations Is shown to Table 1-8.
T*bli 1-8,—Estimated Total Ahkuu Costs
or Implementing ths Interim Fhxart
Danramo Wats* JUotojtionb pom Public
Watem Sttpply BtBTEtas m Mijxionb or
Annual capital*			146-247
Annual operation and maintenance. 283
Annual monitoring (routine only)'.. 17-38
Total annual	 428-5*5
* 1975 dollars.
¦ Assumes capital costs amortized over IS
years at 7-percent Interest.
1.4.1 Wafer supply economics. The price
consumers pay for water Is determined, la
general, by casta tbe utility Incurs to operate
and maintain the system. However, some pub-
licly-owned water systems may have their
costs and revenues conglomerated with the
coat of other municipal services, and the
water- bill paid by the consumer may not
completely reflect the status of the water
system alone.
Water system rate structures vary from
system to system, and may also differ for
various user classes within the same system.
There are four basic types of rate struc-
tures which are used around the country.
Some systems use a "normal block" struc-
ture which results in lower unit costs to
customers that use high volumes of water.
In the "Inverted block" structure, higher
units casta are imposed upon customers who
use higher -volume* of water. Under a "flat-
rate structure, there Is one single charge per
unit" for all customers regardless of use. Gen-
erally, the Sat rate structure applies to resi-
dential customers only. Finally. In the "non-
incremental" rate structure, the unit cost of
water is based on the number of water con-
sumption units owned by the user.
Prices charged for water are usually reg-
ulated hy a State or local commission ap-
pointed to evaluate the need for rate hUes,
In most States, Investor-owned utilities are
"under the Jurisdiction of State regulatory
commissions. Publlely-owned utilities ai®
either regulated by local boards or are un-
regulated. Any lengthy lag time between rate
Increase requests and rate increase approvals
may pose problems In the Implementation of
the interim regulations.
Most water utilities, both public,
vate, finance large capital _lnv-gScment8 by
retaining profits or acquiring "debt. Publicly-
owned, systems may have a.c~CuzvA> rti.'iulclpar
funds or can sell either general obligation" or "
revenue bonds to be repaid from general rev-
enues or water revenues. Private, Investor-
owned systems may Issue stocks and bonds,
and unlike publicly-owned systems, their
credit ratings are dependent on the profita-
bility of their own operations. Since interest
rates are generally proportional to risk, water
utilities In more secure financial positions
can borrow money at lower interest rates. At
the present time the Interest rates 011 mu-
nicipal bonds la 4-8 percent while the rate
for debt issues of private-owned utilities Is
S-8 percent.
In the water industry there does not seem
to be a correlation between present debt lev-
els and long-term financial soundness. Al-
though a majority of water systems -today
have debt ratios ranging upward from 40
percent, almost one-fourth of the water sys-
tems are presently debt-free. Approximately
85 percent of these debt free systema serve
communities of less than 5,000 people. How-
ever, many of these small systems do not
have a positive net income, while larger
water systems with high debt to book value
ratios do have positive net Income.
Records Indicate that per capita consump-
tion oil water tends to decrease following
significant increases in water rates. Among
Individual tisers the decrease would occur
where there Is a high elasticity of demand;
O.g, lawn sprinkling. Industrial and com-
mercial users have shown no elasticity to
price Increases. If demand declines sharply
after initial «.te hikes and total revenues do
not Increase enough to cover Increased east,
a second rate Increase may be neoesaary.
1,4,2 Per capita costs. Monitoring costs
rsry with the sizs of ths wm»r system in-
volved. The number of samples for routine
bacteriological monitoring Is s^funatlca. at
the number o.f persons served. For commu-
nity supplies the number of samples can'
range from a minimum of 1 sample per quar-
ter for systems serving 2000 -peopla or less
to a maximum of 800 samples per month for
systems serving more than 4,890,000 people.
For non-community supplies only one sample
per quarter U required,
In general, the annual impact of routine
chemical monitoring will vary depending on
the frequency of sampUng rather than ths
number of samples. The .frequency gt sam-
pling will depend on the system type:
ground water vs. surface water; txsmsunlty
system vs. nan-community. The annual
monitoring "costs on a per capita basis are
shown in Table 1-6. Ttse pet capita costs
for the smallest community system (as per-
sons served) are high In comparison to
ether system sizes. However, .there &xs very
few systems in this category and tbe Bastes
may desire to enter into Institutional ar-
rangements to lessen their annual monitor-
ing burden.
Table 1-0.—Annual tnonl&orinp cosio per
person served versus	stee - .08
However, treafcmei±* coats may be respon-
sible for much higher per capita cost In-
creases than monitoring costs. As indicated
earlier, public water systema not meeting
the MCL requirements of the interim regu-
lations will incur the major cost burden. The
impact of the treatment costs win also vary
with the size of the water system involved.
Table 1—10 summarises the treatment costs
as they affect systems of different size3.
It should ba pointed out that tbe per
capita costs displayed in Table 1-10 are
weighted averages. Treatment costs have been
weighted by the projected frequency of the
various treatment techniques within each
size subcategory. By its nature, the weighted
average does not give a true representation
of the costs to a particular consumer. In ail
categories, there are five treatments possible
with a wide variation in costs. In Table 1-11,
the range of annual per capita monitoring
and treatment costs are presented. From this
table it can be seen that the annual per
capita treatment costs for disinfection are
expected to range from $3,85 to 82.10 in t»a
Smallest system category, from 32.76 to $0.30
in the Small system category and so on.

. »- Small systems Medium systems Ittrm systems
>idb (25 to w , aoo td 9,999 (io,tw to w,m (over mm
people served) people mrved) people served) people served)
Annus! capital costs (In millions)		t3.BU-J8.iO	150.204101.40	IS2.30-SS8.10
Annual operation and Eoajnteo&ece costs
(in millions)	•.	_	2.10	48.60	74.10
Aanosl moaltorfng east! (la mUMorn)		.60	#0- 1.30	1.20- 2.50
Total annual costs da million*)	 120- 8.10 ICS.40- 161.80 . 117.(6- ML70 16k. M- 188.30
Weijhtfd »*ersie oast per capita per year..
Incntte In household monthly mut bill >.
87.00- M. 00
9.60- 14.05
11.00- 15.00
185- a Mi
8,00- 12.00
2.3*- 3.06
1ft <»• 11.00
18#- 2. SO
> Assumes 3.11 persons par house,bald and that all Increases In cento ara passed  Lower cost limit based on assumption, that treatment plant built to treat average dally demand and op:«r cost
limit based 011 manmum dally demand, (rapt lor the smallest system! category where costs are based on average
dally demand only.
1.4.3 Impact analysis. As Table 1-10 and
Table 1-11 demonstrate, the potentially most
sever# impact could occur for users of the
smallest or 3mail systems. Assuming that
treatment and monitoring costs are dlrsctly
passed on to the consumer, the monthly
water bill for a household 1ft the smallest
systems, may Increase 0x1 the average between
$10 and $14.
.However, as noted earlier, these systems
may ciio—« not to Install treatment facili-
ties in order *, comply with the regulations.
Several options are-ayeugble them:
1.	Developing a new,-"less- caritamt'nHted
source;	J - .
2.	Joining a regional system; ¦
3.	Purchasing treated water; or
4.	Blending water from existing source with
water of higher quality.
The exemption and variance provisions of
the Act provide for temporary; Immunity
from the regulations on^te of,.eco- ,
tiomlc hardship.or technically iffieulties. Peel-'
erai'ioin prfig*™%waji<>also ease the impact
on users of small systems. The Farmers Home
Administration sponsors a loan and grant
program to aid the financing of water and
sewer system construction in small commu-
nities. The loans are ottered at low Interest
rates and with long repayment schedules. The
Safe Drinking Water Act also authorizes a
loan guarantee program for email systems.
These programs will reduce community costs,
but they will not completely = mitigate the
possibility of bigh cost Impacts on house-
holds In small systems.
It 13 not certain how systems will finance
the costs associated with these regulations—
either through higher taxes or higher water
rates—but it is certain that 'the Interim
Drinking Water Regulations will have the
gratest Impact on those served by smaller
water systems. Further study Is underway to
determine if financing will be a serious prob-
lem for large or small systems.
At the present time EPA believes that the
economic impact of the construction require-
ments win be spread over at least a four-year
period from the promulgation of the regu-
lations because the regulations wUl not re-
sult in Immediate compliance. The effective
date of the, regulations will be IB months
after promulgation, Non-compliance may not
be discovered until initial sampling has been
completed. For community water supplies
the deadlines for Initial sampling range from
1 day for turbidity to 2 years for Inorganic
samples of ground water systems after the
effective date. Therefore, In some Cases,
more than 3 years from promulgation could
elapse before Inorganic violations would be
detected and corrective actions initiated. In
addition the use of the exemption or' vari-
ance provisions of the regulations could
further prolong compliance for public water
systems unable to comply for economic or
technical reasons.
It is estimated that the investor-owned
warmer systems .will pay approximately one-* .fl'ti'se total treatment costs, while the
publlcly'-ownt'd companies would pay the re-
mainder. However, since many of .the In-
vestor-owned syste ma serve very small popu-
lations, the capital.! lemands on these systems
. could be 'g^ra.'tfc.
111 '1974, the water supply Industry spent
approximately 81-8 billlpn for capital Im-
provements. The average yearly total annual
capital costs mandated bry the Interim Pri-
mary Regulations are estimated to be about
13 to 24 percent of thia figure. It Is antici-
pated that the Industry as a whole would be
able to raise the additional necessary capital.
Small systems could encounter difficulty in
financing new treatment faculties, particu-
larly when clarification, a relatively expen-
sive treatment process, Is required. The im-
plementation of these Regulations may fores
many communities to allocate funds, which
may be needed to provide other services to
the community, for the treatment of their
drinking water.
Data on non-community systems is sparse.
However, it is not anticipated that these
regulations will have a serious economic Im-
pact on them.
The macroeconomlc effects of the Interim
Primary Drinking Water Regulations are ex-
pected to be minimal. On the average, the
regulations will cause an increase » water
rates of 6.6 percent spread over several years.
If this Increase occurred in one year, the
resulting Increase in the Consumer Price In-
dex (CPI) would be less than 0.001 percent.
Since the costs of these regulations will be
Incurred over several years, the averige an-
nual increase in the CFI will be even lees.
The Chase Econometric model was used to
examine the impact of all existing pollution
aba lament regulations.' The analysis showed
that there will be an average annual Increase
in the DPI for JB74 to 1980 of less than 0.1
percent due to these pollution abatement
1.6 Constraints to implementation of the
interim primary drinking water regulations.
The Implementation of the National Zhterlm
Primary Drinking Water Regulations within
a reasonable time frame would greatly de-
pend on the availability of key chemicals
and supplies needed in the treatment of
drinking water; availability of manpower to
operate treatment facilities; adequate labora-
tory capability to conduct sample analyses;
and sufficient supply of engineering and con-
struction services to build or improve treat-
ment facilities.
In particular, the Interim Regulations will
Increase demand for coagulants and disin-
fecting agents as the needed treatment facu-
lties are completed. A11 Increased demand
could cause some temporary dislocations to
chemical markets, but In the long-run, In-
creased demand will result In an expansion
of supplies. It Is projected that the 1880
demand for ferric chloride may reach 115 to
120 percent of the present production, while
alum demand will be approximately 116 per-
cent of current production. There is a general
consensus of opinion that organic polyelee-
trolytes will become the dominant flocculat-
ing agents In the future. However, there
are no reliable estimates of which polyelec-
trolyte(s) will be dominant and when 'the
shift in chemical usage will occur.	. •
At the present time there are approxi-
mately 190,000 people employed in the water
supply industry. With the implementation
of the Interim Primary Drinking Water Regu-
lations between 13,000 and 27,000 additional
personnel would be needed nationwide. These
personnel would be required to perform such
tasks as monitoring and enforcing the Regu-
lations, operating the required treatment
faculties, performing laboratory analysis of
water samples, program assistance and pro-
gram administration. It Is anticipated that
water systems may have difficulty hiring
qualified personnel.
The third potential constraint is In the
availability of adequate laboratories to per-
form the required chemical and hlological,
analyses. Conform monitoring is now being
performed at State, local and private labora-
tories, In meeting the coliform monitoring
requirements, water suppliers should not
have diOculty finding laboratory facilities.
At the present time there is little routine
monitoring being done for heavy metals and
organic compounds of concern in the Regu-
lations. However, there are adequate num-
bers of public and private laboratories capa-
ble of performing these analyses although
State certification of laboratories, required
by the regxdations, could constrain available
laboratory faculties.
The final area where constraints could
occur is in the design and construction of the
required treatment faculties, Although.the
annual cost of required new construction
represents less than 0.4 percent of the present
total annual new construction in the United
States, design and construction of new water
treatment plants Is highly specialized. Some
communities, especially those in rural areas,
may have difficulty obtaining these services
due to their expense or unavailability.
1 Chase Econometric Associates, Inc. "The
Macroeconomlc Impacts of Federal Pollution
Control Programs," prepared for the Council
of Environmental Quality and the Environ-
mental Protection Agency, January 1976.

1.8 units o/ the anotysit, In developing
the coat estimates used in this Mud?, It was
necessary to uia several simplifying assump-
tions, ThU section explores these assumptions
nnd what their overall impact might be.
The first assumption 1b that ttoere are
40,000 community w»ter supply systems la
the nation and tl»»t they are represented
accurately by the current EPA inventory of
community water supply eyetenu. There la
soma evidence that when the inventory fa
fiompleted there will be a total of 60,000 com- ,
muiiity systems rather than th# estimated
40,000. This Increase In systems would cause
an increase in monitoring costs of about 12
percent and a similar increase In treatment
• cost®.
All costs for public non-community sys-
tems were baaed on th* assuoip,uon that
there are 200,000 oi these aystema nationwide.
At the present time there Is no accurate in-
ventory of these systems, thus, this number
ia solely an estimate. It is anticipated that
the EPA will he performing on Inventory ot
these systems in the next few years bo that
these estimates can be updated.
A major consideration not used in de-
veloping treatment costs la that many sys-
tems may use alternative water management
practices rather than install more costly
treatment processes when they exceed an
MCL requirement. For example, ground water
¦systems might blend water from a "clean"
well with that from a "dirty" well ao that the
resultant water will not exceed the MOL.
Similarly, no estimate is-possible to deter-
mine the possible ben«ftts which might re-,
suit from cascading treatment processes. An
example o£ this is that clarification units
might remove enough heavy metals bo that
the MCL might not be exceeded. These treat-
ment alternatives would vary from cite to
site so that It Is Impossible to quantify the
benefits which would bo derived.
1.7 Energy use. It Is estimated that ap-
proximately 21,200 billion BTD's per year
will be required to operate plants and pro-
duce chemicals for the various treatment
systems necessary for the 10,000 community
systems to meet the regulations. This is
'.about 0,028 percent of the 1973 national
energy consumption, based on the 1914 Sta-
tistical Abstract. The increase In energy use
.will depend'on a number of factors, includ-
ing whether pollution in surface sources
of waters la successfully controlled There
will be no direct energy savings from the
recommended action.
[FR Doc,75-38838 Filed 12-23-75; 8:45 am]
Subpart E—Special Monitoring Regulations
for Organic Chemicals
Pursuant to Sections 1445(a) and
1450(a) (1) ol the Public Health Service
Act, as amended by the Safe Drinking
Water Act, Pub. L. 93-623, the Admin-
istrator of the Environmental Protec-
tion Agency hereby Issues a new 40 CFR
141, Subpart E, to become effective Im-
mediately. This subpart establishes
sampling, monitoring, testing and other
requirements applicable to designated
public water systems for the purpose of
providing data for the establishment of
maximum contaminant levels of organic
contaminants In drinking water.
Concurrently with this publication,
EPA is promulgating National. Interim
Primary Drinking Water Regulations
under the authority of the Safe Drink-
ing Water Act ("SDWA"), Those regu-
lations eoxitaln maximum contaminant
Jevtls, monitoring frequencies and ana-
lytical procedures for microbiological
contaminants, turbidity, and selected
Inorganic «ud organic chemicals. 'The
Interim Primary Milling Water Regu-
lations are to become effective 18 months
after promulgation.
EPA Is embarking on an intensive re-
search progTora to find answers to the
following questions:
1.	What are the effects of commonly
occurring organic compounds on human
2.	What analytical procedures should
be used to monitor finished drinking
water to assure that any Primary Drink-
ing Water Regulations dealing with or-
ganlcs are met?
3.	Because some ¦ of these organic
compounds are. formed during water
treatment, what changes in treatment
practices are required to minimize the
formation of these compounds In treated
4.'	What treatment technology must
be applied to reduce contaminant levels
to concentrations that may be specified
in the Primary Drinking Water Regula-
This research will Involve health-ef-
fects and epidemiological studies, in-
vestigations of analytical methodology,
and pilot plant and field studies of or-
ganic removal unit processes. Some
phases of the research are to be com-
pleted by the end of this year, while
much of the remainder are to be com-
pleted within the next calendar year.
Subpart E Is intended to provide a
rapid means of obtaining data in sup-
port of the possible establishment of
additional maximum contaminant levels
for organic chemical contaminants of
drinking water, either as individual
compounds or groups of compounds.
These regulations will fonn the basis of
a wide-ranging monitoring and analyti-
cal study to be performed by. EPA to
conjunction with the States and desig-
nated participating public water sys-
tems. These regulations will also gen-
erate Information on the occurrence of
potentially hazardous organic chemicals
in a cross-section of public water sys-
tems covering a substantial portion of
the population of the United States and
representing various types of drinking
water sources anc treatment processes.
They will provide Information which is
currently lacking on the actual distri-
bution of a number of organic chemicals
and will make It possible for EPA to at-
tempt to correlate the presence of these
chemicals with the results of.several
general and chemical group analytical
procedures. This Information will aid In
the development of future primary
drinking water regulations.
The recently completed National Or-
ganlcs Reconnaissance Survey iNORS)
reported detection of six volatile organic
compounds In -a sampling of 80 cities.
Extensive additional gas chromato-
graphic/in ass ' spectrometry analyses,
were performed on 10 of these 80 water
systems. However, these were one-time
samples aijd therefore do not indicate
seasonal effects on drinking water qual-
ity nor any other temporary factors
such as intermittent discharge or the
long term effects of treatment appli-
cations In controlling finished water
quality. The special study covered by
these regulations was derived, in part,
from the preliminary results obtained is
the NOR$ Survey and is Intended to re-
spond to many of the questions which it
raised so that the appropriate regula-
tory actions may be determined. Many
of the systems from the previous survey
will be resampled' several times during
this period to provide an indication of
longer-term and seasonal variations In
the quality of drinking water.
This study will include analyse# for
approximately 20 specific organic com-
pounds deemed to be candidates for par-
ticular concern, and analyses of 6 surro-
gate group chemical parameters which
are Indicators of the total amount' of
organic contamination. Several of these
surrogate procedures show promise as
Indicators of specific families of com-
pounds such as chlorinated (halogen-
ated) organics or aromatic compounds.
They also show promise as practical
methods which could be developed and
widely applied for surveillance and qual-
ity control of drinking water In many
water systems, particularly those public
water systenuJ which are' not large
enough to be financially capable of pro-
viding highly sophisticated computerized
gas chromatographic/mass spectromet-
ry analyses.
In order .to assure a rapid and efficient
method of providing data of uniform and
assured quality, EPA wlE assume the
principal responsibility for analysis and
evaluation of the water samples taken by
the designated public water systems. The
water systems Involved may be required
to provide background information and
follow-up Investigation as necessary,
EPA feels that this monitoring study.
In conjunction with Its other substantial
research efforts, will provide the basis
for a coherent and rational approach to
the control of organic chemical contami-
nation of public water systems.
Good cause exists for promulgation of
these regulations without flrst asking for_
comment on them, in view of the wide-
spread public concern, the need to move
as quickly as possible to carry out the
Congressional mandate to deal with or-
ganic chemicals, and In view of the fact
that the burden imposed on designated
public water systems is limited.
Oroahic Chemicals To Be Surveyed
The basic monitoring study will, he
completed within one year and will .In-
volve multiple samplings from each des-
ignated system. Water samples and con-
centrates wOl he collected on site and
shipped to EPA laboratories for analysis.
The study will consist of analyses for
a number of organic compounds and 6.
surrogates In approximately 100 public'
water systems In the United States.
Many of the compounds to be selected
for Inclusion in this study will be halog-
enated and aromatic organic com-
pounds, Virtually no chlorinated organic
«• j

compounds are known to occur naturally
to fresh water. Many are considered to be
liver toxins and/or potential carcinogens
In some concentration. It would be ex-
pected that any chlorinated organic
compounds, found in drinking water
would have been generated either from
Industrial manufacturing operations, ag-
ricultural operations,'or during chlorina-
tion 01 water for the purpose of disinfec-
tion. Many aromatic compounds are also
.considered to be chronic toxicants and
some have been shown to be carcinogens
in test systems such as animal feeding.
Aromatic compounds might also reach
drinking water systems from Industrial
sources, urban surface runoff, or from
atmospheric fallout of materials gener-
ated during combustion processes. Other
possible candidates include aromatic
amines and nltrosamlnes.
The compounds to be studied are being
selected on the basis of available toxicity
data, information on possible occurrence
In public water systems with significant
frequency, and the availability of prac-
tical analytical methods for Identifica-
tion and quantification. They may in-
clude: benzene: carbon tetrachloride;
p-dichlorobenzene; vinyl chloride; 1, 2,
4-triehlorobenzene; bis-(2-chloroethyl)
ether; 1, 1, 2-triehteoettiylenr, 2, 4-dl-
chlcrophenol; fluoranthene; 11, 12-ben-
zofluoranthene; 3, 4-benzofluorar„thene;
1, 12-benzoperylene; 3, 4-bemopyrene;
lndeno (1, 2, 3~cd> pyrene; chloroform;
bromodichloromethane; bromoform; 1,
2-dlchloroe thane; poly chlorinated bi-
phenyls; and pentachlorophenol. Addi-
tional studies will be performed on
aromatic amines (e.g. benzidine) and
In addition to the analyses of specific
compounds, a number of analyses of gen-
eral organic indicators will be performed
In order to determine possible relation-
ships between the presence of th% spe-
cific chemicals and certain general surro-
gate analytic procedures which should
be more applicable for routine monitor-
ing in public water systems. The follow-
ing general indicators will be used;
(1)	Total Organic Carbon analysis
offers promise as a general organic
measurement parameter for -drinking
water and is already widely accepted in
the area of waste treatment organics
monitoring. The procedure indicates the
total amount of organically bound carbon
present in the sample and is not selective
among types of compounds. The tech-
nique essentially consists of oxidation of
the organic chemicals in a water sample
to carbon dioxide which is either quanti-
fied directly or converted to methane
which is then quantified. Sample collec-
tion is simple, analysis is rapid (10 min-
utes) and may be automated, cost per
sample is low, and Interference from in-
organic carbon can be avoided. Reliable
and accurate instrumentation is now be-
coming available for application of this
procedure to drinking water.
(2)	The Ultraviolet and Fluorescence
Spectroscopic methods, which primarily
indicate the presence of aromatic com-
pounds. The advantages of these methods
are sampling simplicity, the small sam-
ple size required, and the speed and low
cost per sample.
<3> Color analyses, which are rela-
tively simple and rapid methods which
may indicate the presence of certain
organic compound types, particularly
huraic substances. Some recent data in-
dicate that relatively , quantitative
relationship may exist between color in-
tensity and the quantity of humle sub-
stances which represent the largest por-
tion of dissolved organic chemicals in
some waters.
(4)	Total Organic Chlorine analyses,
which offer'promise for rapid, accurate
indication of the presence of all chlorine-
containing organic compounds. This pro-
cedure involves oxidation of the halo-
organics in a water sample followed by
mlcrocoulometric quantification, Th#
analysis Is rapid after sample concentra-
tion. The present apparatus has not gen-
erally been applied to drinking water, but
EPA is conducting a concurrent program
to develop the application so that this
potentially important method may be
utilized in this monitoring study.
(5)	The Carbon-Chloroform Extract
procedure (CCE), which consists of pas-
sage of 60 liters of water through a car-
bon column at a constant rate fox 48
hours. The carbon adsorbant is then ex-
tracted with refluxlng chloroform fol-
lowed by removal of most of the chloro-
form and evaporation of the residue to
constant weight. The entire analytical
process requires about 6 days for com-
pletion ana the concentrates represent
something less than 10% of the total
organics content of the sampled water.
Therefore, CCE is not amenable to on-
line process control monitoring. However,
in this study, this CCE data and histori-
cal CCE data will be interrelated with
specific compound analyses and the other
surrogate analyses, to designate the opti-
mum monitoring methodologies for field
use which are most indicative of the pres-
ence of those organic compounds which
potentially pose risks to human health.
Other methods of sample collection and
concentration which are being evaluated
for this and concurrent studies include
the use of macroreticular resins which
have shown promise for application to
drinking water analytical technology.
Within two weeks from the publication
of this subpart, in consultation with the
States, EPA will designate approximately
100 public water systems for inclusion in
the special monitoring program for or-
ganic chemicals. The systems will be se-
lected to represent each major type of
water supply (rivers, impoundments and
ground water), quality of water, treat-
ment, region and population size. Most of
the systems should serve large metropoli-
tan areas, but some may be small enough
to be representative of the water types
and problems associated with smaller
systems. The number of systems to be
selected will be sufficient to permit an
evaluation of the relationship of specific
contaminant concentrations to several
general organic parameters,
EPA in consultation with the State will
work closely with each system to assure
that proper sampling techniques are
used. In addition, when preliminary re-
sults Indicate that a potentially harmful
organic chemical is present in significant
amounts in a particular water system,
EPA and the State will consult with the
system and provide technical advice snd
assistance where appropriate. In some
cases, it may Be possible to-identify a
particular point source which (s caus-
ing serious contanjlnation of a public
water system, or to determine that ad-
ditional treatment should be installed
by a system without waiting for the na-
tionwide survey results.
For the reasons given above. Chapter
40 of the Code of Federal Regulations ts
hereby amended by adding Subpart E to
Part 141, as follows. The new regulations
take effect December 24,1975.
Dated: December 10, 1915.
Russell E, Train.
g 141.40 Special monitoring for organic
(a) The Administrator may designate,
by publication in the Federal Regisibh,
public water systems which are required
to take water samples, provide Informa-
tion, and in appropriate cases analyze
water samples for the purpose of provid-
ing Information on contamination of
drinking water sources and of treated
water by organic chemicals.

FRIDAY, JULY 9, 1976


Title 40—Protection of Environment
[FRL 682-3)
Promulgation of Regulations on
On August 14, 1978, the Environmental
Protection Agency (EPA) proposed na-
tional interim primary drinking water
regulations for radioactivity pursuant to
sections 1412, 1445, and 1450 of the Pub-
lic Health Service Act ("the Act"), as
amended by the Safe Drinking Water
Act, Pub, b. 83-523, 40 FR 34324, Numer-
ous written comments on the proposed
regulations were received, and a public
hearing was held in Washington on Sep-
tember 10, 1975.
The regulations for radioactivity are
hereby promulgated in final form. A
number of changes have been made in
the proposed regulations in response to
comments received. These changes repre-
sent efforts to clarify what are neces-
sarily technical and complex provisions
and to make monitoring requirements
more realistic. The proposed maximum
contaminant levels for radionuclides
have been retained as proposed,
The comments received on the pro-
posed regulations and EPA's response to
those comments are discussed in detail
in Appendix A. The promulgated radio-
nuclides regulations and Appendix A
should be read in the context of the na-
tional interim primary drinking water
regulations as a whole. The regulations
concerning microbiological, chemical
and physical maximum contaminant
levels, and related regulations dealing
with public notification of violations and
reports and record-keeping by public
water, systems, were promulgated on De-
cember 24, 1975, 40 PR 59566.
The balance of this preamble discusses
briefly the Ave major issues highlighted
In the preamble to the proposed radio-
nuclides regulations, and lists In sum-
mary form the changes made In the pro-
posed regulations.
The preamble of the proposed regula-
tions listed five Issues on which com-
ment was particularly requested;
1.	The number and location of the
public water systems impacted by the
proposed maximum contaminant levels
fir radionuclides.
2.	The number and location of water
supplies requiring radium analysis at
the proposed 2 pCi/Iiter gross-alpha-
particle-activity screening level,
3.	The estimated preliminary assess-
ments of the costs and technology for
radium removal.
4.	The validity and appropriateness of
an aggregate dose method for setting
maximum contaminant levels,
5.	The acceptability of a maximum,
contaminant level for radium of 8 pCl/
liter as opposed to a higher or lower level
Public Water Systems Impacted: Lit-
tle significant Information was provided
with respect to the number of commu-
nity water systems that may exceed the
proposed maximum contaminant levels.
The State of Texas did report that 15
community water systems In that State
would exceed the 5 pCl limit for radium:
EPA estimated In Uic preamble to the
proposed regulations that ft total of ap-
proximately -500 of the Nation's commu-
nity water systems would exceed the pro-
posed radium limit. It Is likely that rela-
tively few community water systems cur-
rently exceed the proposed maximum
contaminant levels for either grow alpha
particle activity or man-made radio-
activity. Those levels are intended as
preventative limits rather than as cor-
rective limits.
Public Water St/stems Requiring Ra-
dium Analyst;: The monitoring re-
quirements for the radium maximum
contaminant level provide for an Initial
screening measurement of gross alpha
particle activity to determine if analy-
sis for radium-2 28 is needed. EPA re-
quested comment on the number and
location of community water systems
that would exceed the proposed screen-
ing level of 2 pci/l. A number of com-
ments were received on the possible Im-
pact of the proposed screening level. The
principal concern expressed was that a
2 pCi/Iiter screening level was -unneces-
sarily low and would force a large num-
ber of public water systems to conduct
expensive radium analyses in cases
where the radium limit was not being
A number of cemmentors were under
the impression that radium daughter
products were In equilibrium with radi-
um in drinking water so that their ac-
companying alpha particle activity would
be an indication of radium. Monitoring
data from many public water systems
indicates that because of differences in
solubility and geological processes, the
alpha particle activity is frequently
much lower than would be observed for
an equilibrium mixture of radium and
daughter products and sometimes may be
no greater than that due to radium-226
EPA agrees that in many cases ade-
quate protection can be obtained with
a screening level higher than 2 pCi/Iiter
provided that the precision of the meas-
urement is great enough to insure that
the gross alpha activity Is unlikely to
exceed 5 pCi/1, The regulations have been
amended accordingly. The effect of this
change Is that a screening test, In lieu
of radium analysis, is permitted for most
systems having gross alpha particle ac-
tivities as high as 4 pCl/1, However, as
noted in the Statement of Basis and Pur-
pose for the proposed radionuclide reg-
ulations, care should be taken in evalu-
ating the results of the screening test
because the alpha particle activity screen
does not measure radium-228. a beta
emitter. For this reason, EPA recom-
mends that, in localities where radium-
228 may be present in significant quan-
tities, the Slate establish a screening
level no greater than 2 pCi/liter.
Costs and Technology tor Radium Re-
moval: One comment on radium removal
costs stated that the EPA cost esti-
mates may be too high because new
technologies for radium removal are be-
ing developed. Another comment stated
that the EPA estimates appear "reason-
able at tpls time," and a third that the
estimates are "too general" In that sys-
tem size was not considered.
As discussed in the Statement of BasU
and Purpose for the proposed radionu-
clides regulations, costs for radium re-
moval were found to be essentially in-
dependent of system size for systems
treating less than three million gallons
per day. Since there are no data indi-
cating that the maximum contaminant
level for radium -is being exceeded in
systems larger than this, the EPA cost
estimates are valid.
Three commentors thought the cost
projections for radium removal might
be low because disposal of radium wastes
was not considered. The Agency is pres-
ently conducting a research study to in-
vestigate disposal costs. Compared to
industrial effluents containing radium,
the amount of radium.involved is quite
small. The only available data indicate
that a commercial waste disposal serv-
ice for radioactive materials would be
expected to cost about 50 cents annually
per person served for radium disposal.
However, costs will vary depending on
locality and the disposal method used.
It should also be noted that any radium
disposal problems generated by- the pro-
posed regulations will not be unlike those
already encountered by the many com-
munities already removing radium as
part of their water softening processing. ¦
Other comments suggested considera-
tion of occupational exposure to radium
in water treatment plants. The Agency
has made a limited examination of the
levels of radiation in the vicinity of ion
exchange units used to remove radium
in operating water treatment plants. Ex-
posure levels to operating personnel are
measurable and occupational exposures
could range up to 28-100 mrem/yr. These
doses are well below the Federal occu-
pational guides for radiation workers
of 5000 mrem/yr, Appropriate Federal
Radiation Guidance will be provided if
future studies indicate the problem of
occupational exposure to treatment plant
personnel Is serious.
One commentor questioned the effi-
ciency of radium removal by Ion ex-
change used In the cost analysis in Ap-
pendix V of the Statement of Basis and
Purpose. That analysis shows that treat-
ment cost is relatively Independent of
radium removal efficiency as long as re-
moval exceeds 90 percent. Operating
data from currently used municipal wa-
ter treatment systems indicate that av-
erage radium removal efficiency through-
out the exchange cycle ranges from 93
to 97 percent.
Aggregate Dose Level: As noted in.the
preamble to the proposed radionuclides
regulations, 40 PR 34325, EPA considered
but rejected the use of an aggregate dose
level in establishing maximum contami-
nant levels, This approach would con-
sider both the risk to individuals and the
tot"l risk to the population served, so
that the maximum contaminant level
would be inversely related, within 11m-

Its, to the size of the exposed population
group. Comments on the concept of ag-
gregate dose levels overwhelmingly en-
dorsed EPA'a decision not to use that
approach in the development of maxi-
mum levels under the Safe Drinking Wa-
ter Act.
Maximum Contaminant Level /or Ra-
dium: A number of States submitted
comments on EFA's proposal to establish
the maximum contaminant level for ra-
dium at 5 pd/liter. One State suggested
that a limit of 10'pCI/liter be established
for small public water systems. This sug-
gestion has not been accepted by EPA be-
cause the legislative history of the Safe
Drinking Water Act Indicates that, to
the extent possible, all persons served by
public water systems should be protected
by the same maximum contaminant lev-
els. A number of other States expressed
concurrence in the 5 pel/liter limit.
One commentor cited the results of a
U.S, Public Health Service study that In-
dicated that persons In communities with
water having a concentration of 4.? pCl/
liter had a higher mortality incidence
due to bone sarcoma than persons in
communities with water having less than
1 pCl/liter. The commentor contended
that the USPHS study did not show a
significant difference In cancer risk at
a 95 percent confidence level, and that In
any event the number of excess cancers
was significantly less than would be pre-
dlcted on the basis of the NAS-BEIR
EPA notes that the confidence level of
the USPHS study was 92 percent which
Is not significantly different from a 95
percent criterion considering the overall
precision of the USPHS study. Mortality
estimates on which the 5 pCi/llter limit
was based'included all cancers, not Just
bone sarcoma. Moreover, the EPA esti-
mates are for lifetime exposures, whereas
most of the participants In the USPHS
study were exposed for a substantially
shorter period of time Moreover, the in-
cidence of cancer observed In the USPHS
study is somewhat greater than would be
predicted by the linear dose response
mode] used by EPA. not less as suggested
by the commentor. Given these facts It
Is EPA's view that the USPHS study sup-
ports its use of risk estimates from in-
gested radium as a valid measure of the
Impact of various control levels. EPA
will, however, study new cancer incidence
data as they become available to deter-
mine whether the 5 pCl liter level pro-
vides appropriate protection. '
Changes Made in the Proposed Regu-
In response to comments received on
the proposed regulations, a number of
changes have been made. The comments
and changes are discussed in some detail
in Appendix A. The following list sum-
marizes changes which have been made:
1. Section 141,2 has been revised to
simplify the definitions of "gross alpha
particle activity" and "gross beta parti-
cle activity." As proposed these defini-
tions' were confusing because they sought
to make distinctions which were more
properly set forth In §§ 141,15 and 141.18.
3. Section 141.15 has been changed to
make clear that the maximum contami-
nant level for grnss alpha particle activ-
ity does' not apply to Isotopes of uranium
and radon,
3.	Section 141.16 has been redrafted
for clarity and provisions relating to the
means of determining compliance have
been moved to § 141.26. It should be noted
that the average annual concentration
of strontlum-90 yielding 4 mrem per year
to bone marrow Is 8 pCi/1 not 2 pCl/1 as
was stated In the Proposed Regulations.
Accordingly, Table A In Section 141.16
has been corrected and the detection
limit for strontlum-90 listed in Table B,
1141.25 has been changed to 2pCl/l.
4.	Section 141.25 has been revised to
Include newer analytical methods and to
delete some obsolescent-methods. The
definition of detection limit has been
changed to indicate clearly that it applies
only to uncertainty la the precision of
the measurement due to counting errors.
Also, a new detection limit of 4 pCi/llter
has been established for gross beta par-
ticle activity so that gross beta analysis
may be substituted for strontium-89 and
ceshnn-134 analyses In some cases. It
should be noted that under. 5 141.27 the
State, with the concurrence of the Ad-
ministrator, may authorize the use of al-
ternative analytical methods having the
same precision and accuracy as those
listed in 55 141.25 and 141.26.
5.	Section 141.26 has been redrafted for
clarity and the alpha particle activity
screening level has been redefined to pro-
vide a higher gross alpha screening limit
as long as the precision of measurement
insures that the, gross alpha activity la
unlikely to exceed 5 pCi/1, Also, the re-
quirement for Quarterly sampling has
been revised to permit a yearly sample
where a one-year record based on quar-
terly sampling has indicated the average
annual gross alpha particle activity and
radlum-226 activity to be less than half
the applicable maximum contaminant
level. The period allowed for initial moni-
toring has been extended to three years
rather than two years after the 'effective
date of" these regulations. Also, rather
than reaulre that subsequent monitoring
be every three years for ground water
and every five years for surface water,
monitoring for both ground water and
surface water will be required every lour
6.=	Section 141.26 his been amended to
provide that, when ordered by the State,
a community water system will be re-
quired to participate In a watershed
monitoring program tor man-made ra-
dioactivity. EPA recommends that
States require such programs in each
principal watershed under their jurisdic-
tion. In -addition, the provision allowing
the use of discharge data from nuclear
facilities In lieu of special monitoring for
man-made radioactivity has been
amended to allow only the use of en-
vironmental surveillance data taken in
conjunction with, the State. Also In
1141.28 a screening level for gross beta
particle activity has been established to
reduce the cost of monitoring water sys-
tems affected by i.uclear facilities:
If any screening levels for gross beta
particle activity ore exceeded, Identifica-
tion of specific radionuclides Is manda-
tory prior to public notification and ini-
tiation of any enforcement action. In ad-
dition to the gross beta particle activity
measurement, It may be necessary, as new
energy technologies become available la
theTuture, to monitor for specific man-
made contaminants other than those cur-
rently identified. The Act provides-that
those regulations may be amended from
time to time,
Effective T>atb
Section 1412(a)(3) of the Act pro-
vides that "The interim primary regu-
lations first promulgated • • * shall take
effect eighteen months after the-date of
their promulgation." Hie Interim pri-
mary regulations first promulgated wera
those for microbiological, chemical and
physical contaminants. They were pro-
mulgated on December 24, 1975, and will
become effective June 24, 1977. Because
it Is desirable that all of the basic. In-
terim primary drinking water regulations
take effect on the same date, and In view
of the long lead time provided to public
water systems for compliance with-these
radionuclide regulations, the radio-
nuclide regulations also will become ef-
fective on June 24, 1977.
It Is hereby certified that the eco-
nomic and inflationary Impacts of theso
regulations have been carefully evalu-
ated In accordance with Executive Or-
der 11821, and It has been determined
that an Inflation Impact Statement Is
not required. (The estimated ten mil-
lion dollar annual cost Is less than tha
one-hundred million dollar annual cost
cut-off establlsljpd as the minimum for
which an Inflation Impact Statement to
For the reasons given above. Part 141,
Chapter 40 of the Code of Federal Reg-
ulations is hereby amended as follows:
Russell Trajh,
JtTNi 28, 1976.
1. By revising 1141.2 to Include tha
following new paragraphs (]) through
(o) :
| 141.2 DcfinSlioM.
• * * • •
(j) "Dose equivalent" means the prod-
uct of the absorbed dose from ionising
radiation and such factors as account for
differences in biological effectiveness due
to the type of radiation and Its distribu-
tion m the body as specified by the In-
ternational Commission on Radiological
Units and Measurements (ICRU).
(k> "Rem" means the unit of dose
equivalent from ionizing radiatfon to the
total body or any internal organ or or-
gan system. A "millirem (mrem)" Is
1/1000 of a rem.
(1) "Plcoeurle (pCl)" means that-quan-
tlty of radioactive material producing
2.22 nuclear transformations per min-
(ai) "Gross alpha particle activity"
means the total radioactivity due to

Riplia particle emission as Inferred from
measurements on a dry sample.
(n> "Man-made beta particle and pho-
ton emitters" means all radionuclides
emitting beta particles and/or photons
listed In Maximum Permissible Body
Burdens and Maximum Permissible Con-
centration of Radionuclides in Air or
Water for Occupational Exposure, NBS
Handbook 89, except the daughter prod-
ucts of thorium-232, uranium-235 and
 "Gross beta particle activity"
means the total radioactivity due to beta
particle emission as inferred from meas-
urements on a dry sample.
2. By adding IS 141.15, 141.16, 141.38
and 141.26 as follows:
| 141.IS Maximum contaminant level*
for radium-226, radium-228, and
gtott alpha particle radioactivity in
community water
The following are the maximum con-
taminant levels for radium-226, radium-
228, and gross alpha particle radio-
(a) Combined radium-226 and radJ-
um-228—5 pCi/1.

Ja) The methods specified in mtesiin
Radiochemical Methodology for Drink-
ing Water. Environmental Mar. I boring
and Support Laboratory, EPA-600/4-75-
008, tJSEPA, Cincinnati, Ohio 45268, or
those listed below, are to be used to de-
termine compliance with {5141.15 and
141,16 (radioactivity) except in cases
where alternative methods have been ap-
proved In accordance with { 141,27.
 Gross Alpha and Beta—Method
302 "Gross Alpha and Beta Radioactivity
In Water" Standard Methods for the Ex-
amination of Water and Wastewater,
13th Edition, American Public Health
Association, New York, N.Y., 1971.
(2)	Total Radium	-Method 304 "Ra-
dium In Water by Precipitation" Ibid.
(3)	RadIuni-226—Method 305 "Radi-
um-226 by Radon In Water" Ibid.
(4)	Strontlum-89,B0 — Method 303
"Total Strontium and Btrontium-90 in
Water" Ibid.
(5)	Tritium—Method 308 "Tritium tn
Water" Ibid.
(9! Cesium-134 — ASTM D-2459
"Gamma Spectrometry hi Water," J375
Annual Book of ASTM Standards, Water
and Atmospheric Analysis, Part 31,
American Society for Testing and Mate-
rials, Philadelphia, PA. (1976).
(7) Uranium—ASTM D-3907 "Micro-
quantltiea of Uranium In Water by
Fluorometry," Ibid.

centrations of radioactivity shall monitor
source water, in addition to water from
a free-flowing tap, when ordered by the
uv) Monitoring for compliance with
s 141.15 after the initial period need not
i "!c!'ide radium-228 except when required
by :l-.e State, Provided, That the average
annual concentration of ri»dium-228 has
been assayed at least once using the
quarterly sampling procedure required by
paragraph (a) (1).
¦ vi Suppliers of water shall conduct
annual monitoring of any community
water system in which the radium-226
concentration exceeds 3 pci/l, when or-
dered by the State.
(4i If the overage annual maximum
contaminant level for gross alpha parti-
cle activity or total radium as set forth
in I 141.15 is exceeded, the supplier of a
community water system shall give no-
tice to the State pursuant to § 141.31 and
notify the public as required by 5 141.32.
Monitoring at quarterly Intervals shall
be continued until the annual average
concentration no longer exceeds .the
maximum contaminant level or until a
monitoring schedule as a condition to a
variance, exemption or enforcement ac-
. tion shall become effective.
(,b) Monitoring requirements for man-
made radioactivity in community water
<1> Within two years o£ the effective
date of this part, systems using surface
water sources and serving more than
100,000 persons and such other com-
munity water systems as are designated
by the State shall be monitored for com-
pliance with I 141.16 by analysis of a
composite of four consecutive quarterly
samples -or analysis of four quarterly
samples. Compliance with I 141.16 may
be assumed without further analysis if
the average annual concentration of
gross beta particle activity is less than
~ 50 pCi 1 and if the average annual con-
; centrations of tritium and strontiujn-90
¦ '¦» are less than those listed in Table A. Pro-
vided, That if both radionuclides are
present the sum of their annual dose
equivalents to bone marrow shall not ex-
ceed 4 mllllrem/year.
 Suppliers of water shall conduct
additional monitoring, as ordered by the
State, to determine the concentration of
man-made radioactivity in principal wa-
tersheds designated by the State.
 At the discretion of the State,
suppliers of water utilizing only ground
waters may be required to monitor for
man-made radioactivity.
<2> For the initial analysis required
by paragraph  After the initial analysis required
by paragraph  fl) suppliers of water
shall monitor at least every four years
following the procedure given in para-
graph (b) Q>.
<4i Within two years of the effective
date of these regulations the supplier
of any community water system desig-
nated by the State as utilizing waters
contaminated by effluents from nuclear
facilities shall Initiate quarterly moni-
toring for gross beta particle and Iodine-
131 radioactivity and annual monitoring
for stror.tium-90 and tritium.
(it Quarterly monitoring for gross beta
particle activity shall be based on the
analysis of monthly samples or the ana-
lysis of a composite of three monthly
samples. The former Is recommended.
If the gross beta particle activity in a
sample exceeds 15 pCi/I, the same or an
equivalent sample shall be analyzed for
strontiuin-89 and ceslum-134 If the gross
beta particle activity exceeds 50 pCl/1,
an analysis of the sample must be per-
formed to identify the major radioactive
constituents present ana the appropriate
organ and total body doses shall be cal-
culated to determine compliance with
5 141.16.
iil> For iodine-131. a composite of
Ave consecutive daily samples shall be
analyzed once each quarter. As ordered
",iy the State, more frequent monitoring
shall be conducted when iodine-131 is
identified in the finished water.
fiiii Annual monitoring for stron-
tium-!)!) and tritium shall be conducted
by means of the analysis of a composite
of four consecutive quarterly samples or
analysis ol" four quarterly samples. The
latter procedure is recommended,

Sereral comitwntcrs had difficulty Inter-
preting thla section. It has been redrafted
and that portion of the proposed maximum
contaminant level for mrtn-made radioactiv-
ity dealing with compliance has been moved
to S 141.28 for purposes of clarity.
One commentor questioned the basis of
the selection of the proposed 4 mlllirem an-
imal limit. As stated In the preamble to the
proposed regulations, the four mllllrem per
year limit for man-made radioactivity was
chosen on the basis of avoiding undestrable
future contamination of public water sup-
plies as a result of controllable human ac-
tivities. Current levels of radioactivity In
public water svstems are below the proposed
limit. Appropriate data on this, point is pro-
Tided In the Statement of Basis and Purpose-
Reference was made by one commentor to
ibe Nuclear Regulatory Commission design
criteria for light water reactors which limits
the thyroid dose from a single nuclear re-
actor due to the liquid pathway to ten mll-
llrem per year. The commentor suggested
that this number 1s in conflict with the
proposed maximum contaminant level for
man-made radioactivity. However, because
the two levels are computed on different
bates, lodlne-lSl concentrations meeting
NRC design criteria would also meet maxi-
mum contaminant limits. Therefore, there
18 no conflict between 'these regulations and
NBC' design criteria It should be noted,
however, that'the NEC limits are design cri-
teria. not operational limits, and apply to
only a single nuclear reactor. The EPA max-
imum contaminant limits have a completely
different application, They apply to the fin-
ished waters served by a community water
system which, may use source waters con-
taminated by several reactors or other nu-
clear facilities.
Another commentor staled that the stron-
tlum-SO maximum contaminant level would
produce a bone cancer dose of 4 willirem
per year only after several decades of In-
take. That Is correct—all of the maximum
contaminant levels are based on an assumed
lifetime Ingestion at the concentration
A lew commentors stated that because in
some localities the dose from strontlum-90
In milk exceeds 4 mrem per year, the maxi-
mum contaminant level for strontium-flO In
drinking water should be eliminated or made
greater. Tho Administrator does not agreo
that the radioactive contamination of milk
and milk products, which may occur .in soma
localities, Is a proper basis for relaxing max-
imum contaminant levels for drinking wa-
ter. The maximum contaminant level for
etrontlum-00 is not exceeded in community
water systems at present nor is it likely to
be exceeded In the foreseeable future. To
p«rmlt unnecessary contamination of public
water systems because of other environ-
mental pathways impacting on man would
¦fee Inappropriate.
A few commentors suggested that 2 liters
per day was not an appropriate ingestion
rate assumption for drinking water. The
Administrator notes that a 2 liter per day
Intake Is assumed for establishing maximum
contaminant levels for Ml contaminants, not
Just radioactivity, and that this question
has been discussed at length in the preamble
and Appendix-A to the National Interim
Primary Drinking Water Regulations, 40 FR
A few commentors asked why potassium -
40 was not considered as part of the maxi-
mum contaminant level for beta particle
radioactivity. The amount of potassium In
¦the body Is controlled Uoraostatlcally and la
-not proportional to water Intake levels,
Without the exception for potassIum-40,
some communities might be required to
perform more analytical examination than
necessary if waters exceeded the gross beta
activity screening level. If the Increased beta
activity Is due to potaeslum-40, there la no
Increased risk to users of the public water
systems and therefore such tests are unneces-
i—analytical mkthoSs roa
"Several commentors noted that the Pro-
posed Regulations on analytical methods did '
not allow for the substitution of equivalent
alternative techniques. JEFA agrees that this
Is an important consideration and 9 141,27
has been added to the regulations to allow
substitution of equivalent analytical meth-
od* with the approval of the State and the
Administrator. . Two commentors believed
that no analytical methods should be speci-
fied u part of the regulations, 40 FR 34324.
TUB Administrator believes, however, that
defined analytical methods must be a part
of the regulations so that compliance proce-
dures are uniform and subject to verifica-
Many commentors believed that alterna-
tive analytical methods were preferable to
those listed In the proposed regulations and
several made specific suggestions, EPA recog-
nizes that some of the proposed, analytical
methods were obsolescent and for this rea-
son a new handbook, Interim Radiochemical
Methodology for Drinking Wafer, has been
prepared by the Agency, i 141,25 has been
revised to Include these new methods and to
delete some of the analytical methods pro-
posed earlier. However, some Standard Meth-
ods have been retained because they are
equivalent to the newer procedures and are
currently being used by State laboratories.
Several comments concerned the need for
laboratory certification and quality assur-
ance. EPA will seek to certify at least one
State laboratory in each state. The State may
la turn certify additional laboratories. Pur-
suant to I 141.28, only monitoring results
from laboratories approved or certified by
the entity with primary enforcement respon-
sibility m'ill be acceptable.
.Several comments were received, concern-
ing application of the defined detection lim-
its, The detection limit requirements have
been changed to Indicate clearly that the
Urnlt applies only to uncertainty in the pre-
cision of the measurement due to counting
errors. Other sources of Imprecision and the
overall accuracy of the determination are
not a part of the detection limits given let
this section but rather their control la to
be implemented by means of the quality as-
surance program mentioned previously,
A few commentors believed that the pro-
posed detection limit for gross alpha particle
activity was too tow. Because svstems using
very hard water may be unable to detect
alpha particle activity at the 1 pCi/1 con-
centration, the detection limit for compli-
ance with the gross alpha particle activity
limit. S 141.15(b) has been Increased to 3
pCl/l. This higher detection limit is not
acceptable for gross alpha particle measure-
ments substituted for radium analysis under
I 141.26(a) (1) (1). If water hardness pre-
cludes use of this screening test, a radium
analysis must be made to demonstrate com-
pliance with 5 141 15(1) of these regulations.
Most commentors believed the detection
limits for man-made radioactivity were low
but practicable la laboratories where modern
testing facilities are available,
j H1.2S—MOKrroMuc bcqoiheme^ts fob
The major comments on S 141.28(a) were
that the requirements were not clearly writ-
ten and that the alpha particle activity
screening test for a mandatory radlum-236
measurement was too low thus necessitating
unnecessary expense without Increasing pro-
tection to the public health. Paragraph (ai
has been redrafted to clarify the Intent of
these regulations; and, as discussed ill the
preamble to these regulations, the gross
alpha particle screening level has been In-
Some commentors objected to the require-
ment that quartely monitoring be con-
tinued when maximum contaminant levels
are exceeded and others asked why quarterly
sampling Is needed. The reason why quar-
terly monitoring may provide additional
publLc health protection where maximum
contaminant levels are exceeded is discussed
In the statement of Basis and Purpose. The
Agency agrees that quarterly sampling may
be "unnecessary in some cases and has
amended the regulations to allow a single
yearly sample where a one year historical
record based oa quarterly sampling shows
the average annual gross alpha particle
activity and the radtum-228 activity to be
less than one-half the applicable maximum
contaminant ievelB.
Comments wera divided on sampling fre-
quency. Citizen groups tended to want more
frequent monitoring and the States less fre-
quent monitoring. Of particular public In-
terest was the possible contamination of
ground and surface water by mining opera-
tions, The revised regulations encourage the
State to require more frequent monitoring
for natural radioactivity in situations where
mining or other operations may Impact on
water quality, when new sources of supply
water are utilized or when water treatment
processing Is changed by the supplier of a
community water system.
Several commentors requested an exten-
sion of the Initial two-year period proposed
for mandatory compliance. EPA is aware that
these regulations call for a mora expanded
monitoring effort than is presently Being
carried out by most States. The regulations
have been revised to require that Initial
monitoring begin within two years and that
analysis be completed within three years of
the effective data. In addition, the Agency
has reconsidered, as suggested by several com-
mentors, the proposed requirement that
ground water be monitored every three years
and surface water every five years and be-
lieves monitoring every four years for each
Is appropriate. The regulation has been so"
A few Stales requested that the initial
monitoring of any community water system
for radioactivity be at the discretion of the
State and that the frequency of monitoring
be determined by each State on a ease by
case basis. This is essentially the system now
used, Congress has mandated improved con-
trol of drinking water quality, and these
regulations seek to carry out that mandate.
Two commentors objected to the Agency's
use of a gross alpha screening test to deter-'
mine the need for radium-226 measurements
because such a test is not applicable to
rndium-228. a beta emitter. Since radlum-
226 and radlum-228 are not part of the same
decay series, on® of the commentors believed
an evaluation which measures only gross
alpha particle activity was Inappropriate. It
1s true that radlum-228 and radium-226 am
In different decay series. However, the avail-
able monitoring data indicate that there is
no record of radlum-228 occurring In com-
munity water systems unless it is' accom-
panied by radlum-228. Am pointed out In
the Statement of Basis and Purpose, the
radlum-228 concentration In public water
supply systems is almost always greater than
the rndliim-22B concentration. Therefore, a
screening test based on gross alpha particle
activity is valuable for determining when fur-
ther testing for speclAc radionuclides la

necessary. However, States are encouraged to
require specific analyses for both radium-220
and radlum-228 where radium-228 may be
Several commentors raised questions con-
cerning .the points at which samples are to
be taken and the procedure to be followed
where multiple, or alternate, sources are
utilized As indicated in both the Statement
of Busts and Purpose, and § 141.2(c) of Che
Interim Primary Drinking water Regulations,
sampling is to be done at the "free-flowing
outlet of the ultimate user." Where multiple
sources are employed, the samples should
represent an unbiased estimate of the maxi-
mum, concentration of radionuclides ingested
by persons served by the system.
The Administrator recognizes that in some
communities several wells are used at differ-
ent periods throughout the year to supply
drinking water and that because of different
concentrations of radioactivity in these wells
the concentration In finished water may fluc-
tuate considerably. It Is recommended that
in such cases the States require augmented
sampling programs which include monitor-
ing of source waters. In the revised regula-
tions the State has been given authority to
order such monitoring.
§ 14i.2S
by the State, Other surface water systems
need not monitor for man-mnde radioactiv-
ity. However, it is recommended that all ays-
terns be monitored lor gross beta particle
A large number or respondents were con-
cerned with the number and adequacy of
exIKlng monitoring faculties and the costs
connected with establishing supplemental
facilities In some cases existing monitoring
fnclHtks may not be adequate. The situa-
tion will be more severe for those Jurisdic-
tions where the gross alpha particle eoneen-
trui-jn exceeds the screening level. However,
the higher screen level In the revised regu-
lation will reduce the number of mandatory
radium analyses by a factor of two or more.
Moreover, the phased monitoring require-
ments Imposed by these regulations should
provide adequate time for State and pri-
vate laboratories to add necessary facilities
and equipment. It is true that many small
systems will be required to monitor for
gross alpha activity and, in the aggregate,
bear the major cost impact of the monitoring
requirements However, it is precisely these
systems which are most likely to be con-%
laminated with natural radioactivity. There
is no question but that additional funds wilt
be required for such Increased monitoring.
It was the intent of Congress that these
costs be borne by the individual public water
systems and that corrective measures, such
as consolidation of smaller systems, he em-
ployed to ameliorate this effect,
A few commentors questioned whether-the
proposed limits were "cost effective" in terms
of .both treatment and monitoring costs. A%
stated in the preamble to the proposed reg-
ulations. selection of an appropriate maxi-
mum contaminant level was not based solely
on the estimated cost effectiveness of radium
removal. As explained in the Statement of
Basis and Purpose, the health risk estimates
are uncertain by at least a factor of four
However, the difference In cost-effectrvenew
between different control levels is independ-
ent of this uncertainty and therefore pro-
vides information on where cost-benefit
ratios become significantly poorer The State-
ment of Basis and Purpose also examines
why the cost-effectiveness of radium re-
moval by ion exchange Is low and suggesis
alternative approaches to obtaining maxi-
mum contaminant levels at lower costs. The
cost-effectiveness of the required monitoring
program will depend on the number of sup-
plies Identified as exceeding the maximum
contaminant limits, This cannot be forecast
until the initial monitoring is completed,
In any event, a strict cost-effectiveness ap-
proach is not the intent of the Safe Drinking
Water Act. Maximum contaminant levels are
to prevent adverse health effects to the ex-
tent feasible.
One commentor interpreted a statement In
the Preamble concerning future review of
these reflations, to indicate that the pur-
pose of the Proposed Regulations was to con-
duct R national field survey for radioactivity
in drinking water at State expense A second
comment expressed a similar opinion regard-
ing monitoring requirements for man-made
The rroposM Regulations Arc based on the
Administrator's determination that they pro-
tect health to the extent feasible after tak-
ing treatment costs Into con,«=ideration. He Is
aware that the Agency's estimates of na-
tional cost are dependent on the number of
community water systems impacted and that
an adequate estimate of their number is not
available now. By Congressional manege
these are interim regulations subject to revi-
sion in 1978. Hie Administrator would be re-
mits If be were to ignore new data on the
impact of these regulations as it becomes
available aa an outgrowth of the reporting
Another commentor asked why the Agency
had not set the limit for man-made radio-
activity using n cost-beueflt-approach. The
Agency d>es not believe such an approach Is
either practicable or needed, at this time.
Present levels of man-made radioactivity in
community v&fr systems are quite low—a
statement supported in Appendix III of the
Statement of Basis and Purpose and there la
no evidence that allowing higher concentra-
tions in drinking water would confer signifi-
cant reductions in compliance costs. Effluent
control costs are not likely to be changed by
the proposed regulations for man-made ra-
dioactivity. Effluent control practices of the
nuclear industry as currently regulated ap-
pear to be adequate In terms of the proposed
maximum contaminant limits. The Agency
does not believe it was the intention of
Congress that the cost of removing man-
made radioactivity from public water sys-
tems should be balanced against the cost of
effluent controls required by regulations es-
tablished under other legislation.
Ctilculafionol model* used
One commentor objected to the state-
ment in the preamble concerning the esti-
mated dose due to drinking water contami-
nated by currently operating nuclear fuel
cycle components. The objection was bawd
on two points.
O) That these estimate? were based on
calculations! models, which may not accu-
rately reflect reality.
Thar, the estimates do not consider
aerial depositions from radioactive materials
which are initially deposited Into air and
then fall out onto .the ground and are
washed into waterways.
The Administrator believes the best calcu-
lations! models currently available were
used for these estimates. Measurement of the
actual doses is, of course, impossible at these
low levels. As stated in the Statement of
Basis and Purpose, the Administrator will
consider new models as they are proposed by
appropriate organizations and modify the
proposed regulations as necessary to reflect
new information as it becomes available. By
basing compliance with "maximum contami-
nant levels en measured concentrations of
radioactivity Jn finished drii.kin^j water the
Administrator believes aerial deposition as a
source of water contamination is adequately
Pubtic water systems impacted
One commentor stated that the monitor-
ing data Included in the Statement of Basis
and Purpose for community water systems
were not representative of the radium or
alpha 'particle radioactivity in sections of
the country having abn »rmai!y high concen-
trations of natural radioactivity and there-
fore EPA's estimates of the impact of the
proposed regulations were unrealistic. Tiie
Agency believe? that the-data given in the
Appendix to' the Statement of Fcsls and
rurpose were representative of the country
as a whole, but agrees there are sections of
the country which routinely have" higher
amounts of radium In' their community
water systems. However, as stated in the
Statement of Basis and Purpose, these na-
tional data were not used aa a basis for the
EPA estimate of the number of public water
Fystems impacted by the proposed maximum
contaminant limit for radium. Rather, that
estimate Is based on other monitoring data
obtained mostly in regions where significant
amounts of radium are commonly found In
community water systems, as referenced in
the Statement.
Linear nonthreshold response functions
On© commentor stated the Agency was too
conservative in the estimation of possible
health effects because a linear nonthreshold
dose response function was assumed. Another
commentor stated a linear nonthreshold re-
lationship is not conservative enough since
an increased radioearclnogchic response has
been associated with low dose rates from
alpha pari irlo irradiation. Converse!}", one
commentor stated that there is a threshold
for radiation injury from ingested radium and
that the maximum contaminant level for
radium should be based on bis value for a
threshold dose. Reasons for using a linear
nonthreshold dose response were given In
full in Ihe Statement of Basis and Purpose
and are reproduced here as Part III of this
Appendix, The Agency is aware that one study
on the results of clinical treatments with
radium-224 indicates that protraction of the
alpha exposure is more carcinogenic and that
it has been hypothesised that lung cancer
may be" associated with very low dose rates
from alpha particle emitters. Also, analyses
of the radium dial painter data'have been
interpreted as Indicating that bone cancers
from lower radium doses occur later In life
than, from large doses and this has been in-
terpreted as an argument for an effective
threshold. However, the United States Public
Health Service has studied this question in
some detail, BRH/OTE 70-5, and EPA agrees
with the XTSPHB finding that the data are
Insufficient to specify an unequivocal dose
response made! and their conclusion Uiat,
"* * ¦ in the low dose region expected to
be experienced by the general public, the
assumption of a linear nonthreshold model
continues to be a prudent public health
philosophy for standards setting."
Two Slates requested a definition of "nu-
clear facility." As explained la the Statement
of Basis end Purpose, -the term "nuclear fa-
cility" Is flexible &o that the States may de-
termine which community water systems re-
quir& additional monitoring. The term "nu-
clear facility" should not be construed as
applying only to nuclear electric-generating
plants and other components in the uranium
fuel cycle but may also Include, at the op-
tion of the State, waste storage areas, experi-
mental facilities, and medical centers as out--
lined in the Statement of Basis and Purpose.
Pour commentors believed that the pro-
posed regulations would be difficult for per-
sons working in community water systems
to understand—that they were too technical.
EPA agrees this is a Highly technical subject
not amenable to Jay -terms. However, the
Agency has attempted to clarify the regula-
tions and believes that all States have radio-
logical health personnel who are willing to
assist a supplier of water if particular prob-
lems of interpretation arise.
Several commentors expressed the opinion
that data collected prior do Implementation
of the proposed regulations should be ad-
missible as evidence of compliance. EPA
Rgreea arid the regulations have been modi-
fied so that analytical data acquired one year
"prior to the effective date of these regula-
tions may be substituted for monitoring re-
quired during the initial period at the dis-
cretion of the State. This should reduce ini-
tial monitoring costs.
Two commentors expressed concern about
adverse health effects that mlgbt occur as a
result of sodium addition to water during
the zeolite softening process. Possible health
effects from sodium were considered In de-
tail by the Agency In the development of the
proposed regulations for Inorganic chemi-
cals, as well as for radium, and: are discussed
in the Statement of Basis and Purpose. The
federal iegistir, vol. 41, no. 133—fsioay, juiy 9, w*

Agency believes It not appropriate to Bet a
maximum contaminant level for bodium.
Tlte consensus of opinion among medical
personnel in this field la that, while the
sodium added is not negligible, patients on a
restricted, but noncrltical, sodium diet would
not be adversely affected at the Increased
levels contemplated. Patients for whom the
Increased levels might be critical are not
normally permitted to um regular drinking
water supplies but are restricted to specially
processed water. The statement of Bosls and
Purpose recommends that community physi-
cians having patients In areas where the
concentration of sodium is Increased due to
radium removal be so informed by the sup-
One commentor took exception to the sug-
gestion in the preamble that, taken as a
whole, releases from hospitals and other In-
dustrial facilities would result In doses com-
parable to those released from nuclear fa-
. cliltles such as light water reactors. The
statement In the preamble was not based on
a full scale technical evaluation. The Agency
' Is studying releases of radioactive materials
from Hospitals and other complexes through
contractor research and will amend this
estimate as necessary based on theue and
other findings.	•
Several respondents were in doubt as to
the responsibilities of the water supplier In
terms of actual performance of the required
analyses. Allied questions were directed to
whether the supplier of water or the State la
responsible for the cost of analyses,
"It is the intent of the regulations that the
Individual water supplier, while responsible
for compliance with the regulations, may
reasonably be expected to collect and trans-
mit water samples to approved laboratories
for actual performance of the radloanalyals.
It U the Intent of both Congress and these
regulations that the principal costs associ-
ated with compliance with the Safe Drinking
Water Act be borne by the individual public
water systems, However, a State Is not
barred from analyzing samples for public
water systems without charge.
One commentor wanted to Know if the
proposed maximum contaminant levels for
radioactivity in drinking water replaced
¦ Federal Radiation council Outdance on
Radiation Protection Ouldes for the general
population. These regulations do not replace
PRO recoroendations on the transient Intake
of radioactive materials, which included both
'the food and water pathways, and which
contemplated, except in the case of radium,
exposures of less than a lifetime duration.
EPA believes that the PRC Range XI limit for
large population groups cannot be applied
to a single pathway, such as drinking water,
since FRC Guides include exposure from
external radiation. Inhaled radioactivity and
radioactivity In food as well as drinking
Three commentora questioned basing the
maximum contaminant limits on the same
dose limit whether applied to any internal
organ or to the whole body. EPA haa consid-
ered this question with care in developing
these regulations, Recognizing that th# con-
servatism of the maximum contaminant
limits was increased by this decision. Th®
decision not to consider critical organs for
the ingestion of radioactivity la drinking
water Is based on the National Committee
on Radiation Protection (NCRP) recom-
mendations contained In NCRP Report No,
39. In that report, the NCRP recommended
that organ dose limits for the general popu-
lation be baaed on whole body does and not
at a fraction of the corresponding occupa-
tional dose limit for critical organs. The
NCRP decision was in part based on the lack
of data available at that time to consider
appropriately the risk from a radiation Insult
to various organs. Such data are becoming
available now and the International Com-
mission on Radiation Protection (ICRF) Is
considering basing dosi limits on the risk to
various organ systems. When the ICRP rec-
ommendations are developed In final form
they will be considered by EPA-
r*»T in
OMP Policy Statement on the Relationship
Betwcrn RaHatton Dose and Effect; March
3, 197S
The actions taken by the Environmental
Protection Agency to 'protect public health
and the environment require that the Im-
pacts of contaminants in the environment or
released into the environment be prudently
examined. When these contaminants are ra-
dioactive materials and Ionizing radiation,
the siut Important impacts are those ulti-
mately affecting human health. Thereto™,
the Agency believes that the public Interest
Is best served by the Agency providing its
best scientific estimates of such Impacts in
terms or potential 111 health.
To provide such estimates. It la.necessary
that judgments be mode which related th*
presence of Ionizing radiation or radioactive
materials in th© environment, l.e„ potential
exposure, to the intake of radioactive mate-
rials in the body, to the absorption of en-
ergy from the Ionizing radiation of different
qualities, and Anally to the potential erecta
on human heaJth. In many "situations the
levels ol Ionizing radiation or radioactive
materials in the environment may be meas-
ured directly, but the determination"of re-
sultant radiation doses to humans and their
susceptible tissues Is generally derived from
pathway und metabolic models and calcula-
tions of energy absorbed. It Is also necessary
to formulate the relationship between ra-
diation dose and effects; relationships de-
rived primarily from human epidemiological
studies but also reflective of extensive re-
search utilizing animals and other biologi-
cal systems.
Although much la known about'radiation
dose-effect relationships at high levels of
dose, a great deal of uncertainty exists when
high, level dose-effect relationships are ex-
trapolated" to lower levels ol dose, particular-
ly when given at low dose rates. These un-
certainties la the relationships between dose
received and effect produced are recognized
to relate, among many factors, to differences
in quality and type of radiation, total dose,
dose distribution, doee rate, and radloeensl-
tivlty. Including repair mechanisms, sex, vari-
ations In age, organ, and state Df health.
These fatcors Involve complex mechanisms
of interaction among biological chemical, and
physical systems, the study of which is part
of the continuing endeavor to acquire new
scientific knowledge.
Because of these many uncertainties, It
is necessary to rely upon the considered
Judgments of experts on the biological effects
of Ionizing radiation, These findings are well-
documented la publications by the United
Nations Scientific Committee on the Effects
of Atomlo Radiation fOTTSOEASj, the Na-
tional Academy of sciences (NAS), and the
National Council on Radiation Protection
and Measurement* (NCRP), and have been
used by the Agency In formulating a policy
on relationship between radiation dose and
effect, .
It is the present policy of the Environ-
mental Protection Agency to assume a linear,
nonthreshoid relationship between the mag-
nitude of the relation dose received at en-
vironmental levels of exposure and 111 health
produced.aa a means t-o estimate the poten-
tial health Impact of actions It takes in de-
veloping radiation protection as expressed In
criteria, guides, or standards. This policy la
adopted in conformity with the generally ac-
cepted assumption that there is some poten-
tial ill health attributable to any exposure
to Ionizing radiation and that the magnitude
of this potential 111 health directly propor-
tional to the magnitude of the dost received.
In adopting this general policy, the Agency
recognizes the inherent uncertainties that
exist in estimating health Impact at the low
levels of exposure and exposure rates expected
to "be present In the environment due to
human activities, and that at these levels
the actual health Impact will not be dis-
tinguishable from natural occurrences of 111
health, either statistically or In the forma
of 111 health present. Also, at these very low
levels, meaningful epidemiological studies
to prove or disprove this relationship are
difficult, if not practically impossible to COB-
duct. However, whenever new Information la
Jar incoming, this policy will be reviewed and
updated as necessary.
It la to be emphasized that thU policy hu
been established for the purpose of estimat-
ing the potential human health Impact of
Agency- actions regarding radiation protec-
tion, and that such estimates do not neces-
sarily constitute Identifiable health conse-
quences. Further, the Agency implementation
of this policy to estimate potential human
health effects presupposes the premise that,
for the same dose, potential radiation effects
in other constituents of the biosphere will
b« no greater. It Is generally accepted that
such constituents are not more radiosensi-
tive than humans. The Agency believes th#
policy to be-a prudent one.
In estimating potential health effects It la
Important' to recognize tbat the exposures
to be usually experienced by the public will
be annual dosee that? are small fractions of
natural background radiation to at most a
few times this level. Within the OS. the
natural background radiation dose equiva-
lent varies geographically between 40 to 300
mrem per year. Over such a relatively small
range of dose, any deviations from dose-eSect
linearity would not be expected to signifi-
cantly affect .actions taken by the Agency,
unless a doae-eifect threshold exists.
While the utilization of a linear, non-
threshold relationship Is useful as • gen-
erally applicable policy for assessment of
radiation effects. It la alao EPA's policy in spe-
cific situations to utilize the best available
detailed sclent Lac knowledge In estimating
healtB Impact when such information la
available for speciflc types of radiation, con-
ditions of exposure, and recipients of the ex-
posure. In such situations, estimates may or
may not be based on the assumptions of lin-
earity and a nonthreshoid dose. In any case,
the assumptions will be stated explicitly to
any EPA radiation protection actions.
The linear hypothesis by Itself preclude!
the development of acceptable levels of risk
based solely on health considerations. There-
fore, In establishing radiation protection
positions, the Agency will weigh not only Um
health impact, but also social, economic and
other considerations associated with the ac-
tivities addressed.
[Hi DOC.78-IB30S Filed 7-6-78; 8:M am)
FEDERAL KGISTfll, VOL 41, NO. 133—filOAT, JUIY 9, IW


Proposed Regulations
[ 40 CFR Part 143 ]
Proposed Regulations
Notice is hereby given that pursuant
to section 1412 of the Public Health Serv-
Volume 42 ¦ Number 62

ice Act, as amended by the Safe Drinking
Water Act ("the Act," Pub. L. 83-523).
the Administrator of the Environmental
Protection Agency (EPA) proposes to
issue a new 40 CFR Part 143 setting forth
Secondary Drinking Water Regulations.
The Act was signed by the President
on December 16, 1974. It Is the first Fed-
eral Act dealing In depth with providing
safe drinking water for public use. Na-
tional Interim Primary Drinking Water
Regulations were proposed on March 14,
1875, and promulgated on December 24,
1975. Regulations covering radionuclides
were added on July 0, 1978. The regu-
lations proposed today, the secondary
regulations, follow and complement the
primary regulations. While primary reg-
ulations are devoted to constituents and
regulations affecting the health of con-
sumers, secondary regulations are those
which deal with the esthetic qualities of
drinking water. The contaminants for
which Secondary Maximum Contami-
nant Levels are set In these regulations
may not have a significant direct Impact
on the health of consumers, but their
presence In excessive quantities may dis-
courage the utilization of a drinking
water supply by the public.
Primary drinking water regulations
are applicable to all public water systems
and are enforceable by EPA or the States
which have accepted primacy; secondary
regulations are not Federally enforceable
and are Intended as guidelines for the
States, EPA expects the States to give
priority attention to implementation of
the mandatory primary regulations
which provide health requirements. .
Section 1414 of the Act provides:
(dS Whenever, on the basis of information
available to .Urn, the Administrator flnds
that within a reasonable time after National
Secondary Drinking Water Regulations have
been promulgated, one or more public water
systems in a State do not comply with such
secondary regulations, and that «ueh non-
compliance appears to result from a failure
of such State to take reasonable action to
assure that public water systems throughout
such State meet such secondary regulations, •
he shall so notify the State.
EPA does not propose to use its re-
sources, on a routine basis, to indepen-
dently determine compliance or noncom-
pliance with the secondary regulations.
It will, however, review"data which may
be reported by the States on a discre-
tionary basis or which is received inci-
dental to other studies. On the basis of
such review, the agency will consult with
the States to determine the action taken
by them to assure compliance and where
appropriate, notify States of noncompli-
ance which has not been acted on.
Secondary Maximum Contaminant
The Secondary Drinking Water Regu-
lations contain maximum contaminant
levels for chloride, color, copper, cor-
rosivlty, foaming accnts, hydrogen sul-
fide, iron, manganese, odor, pH, sulfate,
total dissolved solids and zinc. Brief
statements on the effects of these on wa-
ter quality are listed, and more detailed
comments are available in the Statement
of Basis and Purpose, available as de-
scribed in the last section of the
Chloride in reasonable concentrations
is not harmful to hunions, but in concent
trations above 250 ma/1 chloride causes
a salty taste In water which la objection-
able to many people. Chloride can be re-
moved from di'lnking water by distilla-
tion, reverse. osmosis or electrodlalysts,
but in some cases the entry of chloride
Into a drinking water source can be
minimized by proper aquifer selection
and well construction,
Color may be indicative of dissolved
organic material which may lead to gen-
eration of trlhalomethanea and other or-
ganohalogen compounds during chlorl-
nation. Color can also be caused by inor-
ganic species such as manganese or iron.
Color becomes objectionable and an-
esthetic to most people at levels over 15
C.U. (Color Units). In some cases, color
can be objectionable at the 5 C,U. level,
and States, therefore, should also con-
sider the regulation of color at levels be-
low 15 C.U. Depending on the nature of
the substances causing color, conven-
tional water treatment < flocculatlon and
filtering), oxidation or carbon adsorption
are processes used for removing color.
Copper Is an essential and beneficial
element in human metabolism, but cop-
per imparts an undesirable taste to
dniiking water. Small amounts of copper
are generally regarded as nontoxic'. Cop-
per can be removed from water by ion
exchange, and by proper control of pH,
where the source of copper is the cor-
rosion of copper pipes,
Corrosivity is a complex characteristic
of water related to pH, alkalinity, dis-
solved oxygen and total dissolved solids
plus other factors. A corrosive water, in
addition to dissolving metals with which
It comes in contact, also produces objec-
tionable stains on plumbing fixtures. Cor-
rosivlty ts controlled by pH adjustment,
the use of chemical stabilizers, or other
means which arc dependent upon the
specific conditions of the water system.
The corrosivity of drinking water is a
parameter which has not only esthetic
significance, but health and economic
significance as well. The products of cor-
rosion having the greatest health signif-
icance, cadmium and lead, are addressed
in primary regulations, but there is also
a sufficient basis to Include corrosivity in
secondary regulations. The problem lies
in the lack of a simple, generally accep-
table means for measuring the corrosiv-
ity of water and thus the lack of a gen-
erally acceptable numerical index for as-
sessing and limiting corrosivity. There
are a number of indices in use. but no
agreement on a single one which would,
in all cases, definitively say whether or
not a iiven water was corrosive. An at-
tempt to circumvent the problem can be
made by specifying, in lieu of an Index,
practical tests of corrosivity using pipe
sections, metal coupons or water analyses
for the determination of the corrosive
properties of a water. Unfortunately,
most of these tests, as well as most in-
dices, are not universally applicable and
require long periods of time to carry out
or develop. For a corrosivity test or index
to be widely used and applied, the testing
procedure must be rapid, simple and gen-
erally applicable. Comments are solicited
from the public on a practical means for
assessing corrosivity, as well as an as-
sociated number to be used as a Second-
ary Maximum contaminant Level.
Foaming is a characteristic of water
caused principally by the presence of de-
tergents and similar substances. Water
which foams is definitely unesthetic and
considered unfit for consumption. The
foamabillty of water Is measured by the
quantity of methylene blue active sub-
stances (MBAS) present. Foaming sub-
stances can be removed from drinking
water by carbon adsorption, but it is
preferable to prevent contamination of
water by these substances.
Hydrogen sulfide is an odorous gas. Its
presence in drinking water Is often at.
trlbuted to microbial action on organic
matter or the reduction of sulfate ions
to sulfide. In addition to its obnoxious
odor, hydrogen sulfide in association with
soluble iron produces black stains on
laundered items and black deposits on
piping and' fixtures. Hydrogen sulfide is
removed from drinking water by aera-
tion or chemical oxidation.
Iron is a highly objectionable constit-
uent of water supplies for either do-
mestic or industrial use. Iron may im-
part brownish discoloratlons to laund-
ered goods. The taste that it imparts to
water may be described as bitter or
astringent, and iron may adversely affect
the taste of other beverages made from
water. The amount of iron causing ob-
jectionable taste or laundry staining con-
stitutes only a small fraction of the
amount normally consumed in the daily
diet and thus does not have toxicologic
significance. Iron can be removed from
water by conventional water treatment
processes or Ion exchange and also by
oxidation processes followed by filtering.
If the iron comes from the corrosion of
iron or steel piping the problem can
often be eliminated by practicing corro-
sion control,
Manganese, like Iron, produces dis-
coloration in" laundered goods and Im-
pairs the taste in drinking water and
beverages, including tea and coffee. At
concentrations In excess of 0.05 milli-
grams per liter, manganese can occasion-
ally cause buildup of coatings in distri-
bution. piping which can slough off and
cause brown spots in laundry items and
unethetlc black precipitates, Managa-
nese can usually be removed from water
by the same process used for iron re-
Odor is an Important esthetic quality
of water for domestic consumers and
process industries such as food, beverage
and pharmaceutical manufacturers,
which require water essentially free of
taste and ordor, It is usually Impractical
and often Impossible to isolate and iden-
tify the odor-producing chemical. Eva-
luation of odors and tastes is thus de-
pendent on the Individual senses of smell
and taste. In many cases, sensations as-
cribed to the sense of taste are actually
odors. Odors are usually removed by car-
bon adsorption or aeration.
The range of pH in public water sys-
tems may have a variety of esthetic and
- 108

health effects. Corrosion effects are com-
monly associated with pH levels below
6.S. A3 pH levels are Increased to above
I S mineral incrustations and bitter taste
can occur, the germicidal activity of
chlorine Is substantially reduced and the
rate of formation or trihalomethanes Is
significantly Increased, However, the Im-
pact of pH In any one water system will
vary defending on the overall chemistry
and composition of the water so that a
more or less restrictive range may be ap-
propriate under specific circumstances.
Sulfate may cause detectable tastes at
concentrations of 350-400 milligrams per
liter; at concentrations above 600 milli-
grams per liter It may have a laxative ef-
fect. High, concentrations of sulfate also
contribute to the formation of scale In
boilers and heat exchangers. Sulfate can
be removed from drinking water by dis-
tillation, reverse osmosis or electrodialy-
sis. The laxative effect noted above
seldom affects regular users of the water
but transient-? are particularly suscep-
tible, For this reason it is recommended
that States institute monitoring pro-
grams for sulfate, and that transients be
notified If the sulfate content of the
water Is high. Such notification should
include an assessment of the possible
physiological effects of consumption of
the water.
Total Dissolved Solids  may
have an Influence on the acceptability
of water in general, and in addition a
high TDS value may be an Indication
of the presence of an excessive concen-
tration of some specific substance that
would be esthetically objectionable to
the consumer. Excessive hardness, taste,
mineral deposition or corrosion are com-
mon properties of highly mineralized
water. Dissolved solids can be removed
by chemical precipitation In some cases,
but distillation, reverse osmosis, electro-
dialysis and ion exchange are more gen-
erally applicable.
Zinc, like copper, is an essential and
beneficial element In human metabolism,
fZinc can also Impart an undesirable
taste to water. At higher concentrations,
zinc salts impart a milky appearance to
water. Zinc can be removed from water
by conventional water treatment proc-
esses or ion exchange, but since the
source of zinc is often the coating of gal-
vanized iron, corrosion control will mini-
mize the introduction of zinc into drink-
ing water. At the same time, corrosion
control will minimize the introduction
of lead and cadmium into the drinking
water, since lead and cadmium are often
contaminants of the zinc used in gal-
Contaminants Constbemb But Noi
Included In The Regulations
In addition to the above contaminants,
several other drinking water parameters
were considered for inclusion In these
regulations. Among these are hardness,
alkalinity, phenols, sodium and standard
plate count,
Since high levels of hardness have
significant esthetic and economic effects,
.'the removal of hardness (softening)
can be considered beneficial from a non-
health Ikidpoim. However, correlation*
between the softness of water .and the
incidence of Cardiovascular disease have
been shown. In some studies', so the prac-
tice of softening drinking water Is being
discouraged by some scientists ¦ and
physicians. Available information is not
sufficient at this time , to balance the
esthetic desirablty of settng a limit;for.
hardness against the potential health
risk of water sof tenlng.
Phenols, particularly the chloro-
phenols, are esthetically objectionable
because of the taste and ordor they
produce, Some of the chlorophenols
produce a detectable taste or odor at
concentrations as low as 1 ppfc. While
analysis for phenols in this concentra-
tion area might present some difficulties,
the odor test can easily detect the
presence of these compounds and thus
makes the inclusion of a limit for phenols
The principal concern-with respect to
sodium relates to its potential health
significance rather than to esthetic ef-
fects. However, existing data did not
support the establishment of a Maxi-
mum Contaminant Level for sodium in
the Interim Primary Drinking Water
Regulations. It is recommended that
the States institute programs for regu-
lar monitoring of the sodium content of
drinking water served to the public, and
for informing physicians and consumers
of the sodium concentration in drinking
water. By this means, those affected by
high sodium concentrations can make
adjustments to their diets, or seek alter-
native sources of water to be used for
drinking and food preparation.
It has been suggested that standard
plate count, a measure of bacterial con-
centration, be included as an esthetic
parameter in these regulations but it
causes no observable esthetic effect and
consequently Is not appropriate for
inclusion. Microbiological MCL's are
contained in the National Interim Pri-
mary Regulations,
Since these regulations are not Fed-
erally enforceable, there are no asso-
ciated monitoring requirements. As a
practical minimum, however, it is recom-
mended that the contaminants listed in
these regulations be monitored along
with the inorganic chemicals monitored
to determine compliance with the pri-
mary regulations. Obviously, some pa-
rameters are subject to frequent varia-
tions and, therefore, may need to be
monitored more frequently. The States
may wish to supplement these Yegula-
tions with more specific monitoring re-
quirements in their own laws and
Economic Impact
As noted above, the Secondary Drink-
ing Water Regulations are not Federally
enforceable, so the extent of their Im-
plementation and thus the associated
economic impact Is Impossible to Judge.
However, since there are data available
on the prevalence of some of the con-
taminants listed in these regulations
and since treatment costs "are also avaiM
able, a limited economic evaluation has
been prepared. Actual compliance will
depend on the level of State implementa-
tion, and customer dissatisfaction and
willingness to pay for improvements. ¦
Hie limited evaluation considers cost
Impacts on consumers In different alee
systems for treatment to remove, iron
and manganese and to adjust pH levels
for corrosion control, It demonstrates
that, esthetic.parameters are exceeded
most often In small water systems with
only'a low rata of exceeders in the larger
systems. For example, in the National
Community Water Supply Study. 25 per-
cent of the systems failed at least one
esthetic limit but this represented only
12 percent of the study population; con-
versely 86 percent of the study popula-
tion had esthetically satisfactory water.
The per-customer costs of providing
Iron and manganese control and pH ad-
justment for corrosion control were sub-
stantially greater for small water sys-
tems than for the large systems. The
monthly cost per household was esti-
mated at $3 60 (25-99 persons served)
as against f 1.10 for systems serving over
100,000 and recent field data indicate
that the small system costs may be much
higher under some circumstances, These
data may provide the reason for the
probable existence of more frequent
esthetic quality problems in small sys-
tems vOhere the customer may be willing
to accept a lower esthetic quality water
rather than to pay higher treatment
costs. These cost data can be used by
States and communities as indicators
of approximate cost of compliance.
Further information regarding the eco-
nomic evaluation may be obtained from
the Office of Water Supply.
Comments and Ptrstic Heaxino
Interested persons may participate in
this rulemaking process by submitting
written comments in triplicate to the
Office of Water Supply (WH-550),
Criteria and Standards Division. En-
vironmental Protection Agency, Wash-
ington. D C. 20«0.
During the development of these pro-
posed regulations, additional suggestions
were received, Including a recommenda-
tion that, for Total Dissolved Solids,
chloride and sulfate, three different
levels be set (1) a Recommended Level,
(2) an Upper Limit and <3> a Short-
Term Limit. The Recommended Level
would represent the desirable concentra-
tion for a high degree of consumer ac-
ceptance; the Upper Limit would be ac-
ceptable when it is not reasonably feasi-
ble to provide more suitable water; and
the Short-Term Limit would be con-
sidered acceptable only for existing sys-
tems pending construction of treatment
facilities or development of new water
sources. Other suggestions were that
more frequent. monitoring be recom-
mended for constituents, such as color
and odor, whose concentrations vary
from day to day. Sodium has also been
suggested for Inclusion in the secondary