United States
Environmental Protection
Agency
Office of
Drinking Water (WH-550)
Washington DC 20460
August 1983
EPA 570/9-83-002
Water
Trihalomethanes
in Drinking Water
Sampling, Analysis,
Monitoring and Compliance
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TRIHALOMETHANES IN DRINKING WATER
Sampling, Analysis, Monitoring and Compliance
AUGUST 1983
Science & Technology Branch
Criteria & Standards Division
United States Environmental Protection Agency
Washington, D.C.
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TABLE OF CONTENTS
Descri pti on Page
INTRODUCTION 1
EFFECTIVE DATES OF MCL, MONITORING AND REPORTING 2
REQUIREMENTS
MONITORING FOR THMS 3
Triha 1omethane Analysis 3
MTP (Maximum Trihalomethane Potential) 3
ReducedMonitoringRequirements 5
WhentoMonitor 9
SamplingLocations 11
Surveillance for Other Organic Compounds 12
DETERMINATION OF COMPLIANCE WITH MCL 13
CONSECUTIVE SYSTEMS 15
THE ROLE OF MSIS 16
MICROBIOLOGICAL CONCERNS AND SAFEGUARDS 17
Evaluation of System for Sanitary Defects 17
EvaluationofTreatmentOptions 20
Baseline Water Quality Survey 20
APPROACHES TO CONTROLLING TTHMS 27
LABORATORY CERTIFICATION CRITERIA FOR
TRIHALOMETHANES 34
APPENDIX 41
R-2A Media Preparation 42
Water Supply Guidance #72 43
Public Notification Requirements 44
Water Supply Guidance # 74 45
References 47
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INTRODUCTION
On November 29, 1979, the Environmental Protection Agency
(EPA) promulgated an amendment to the National Interim
Primary Drinking Water Regulations (NIPDWR) to control
trihalomethanes (THMs) in drinking water (see 44 F.R. 68624).
The amendment established a maximum contaminant level (MCL)
of 0.10 mg/1 and associated monitoring and reporting require-
ments for total trihalomethanes (TTHMs). Community water
systems which use a disinfectant and serve more than 75,000
persons were to begin monitoring and be in compliance with
the MCL, 1 and 2 years, respectively, following promulgation.
Community systems which use a disinfectant and serve 10,000
to 75,000 persons are to begin monitoring and be in compliance
with the MCL 3 and 4 years, respectively, following promul-
gation .
On February 28, 1983, EPA published an amendment to the TTHM
implementation regulations (see 48 F.R. 8406). This amendment
defines both those treatment techniques which the Administrator
has determined are generally available (taking costs into
consideration) for TTHM control and criteria by which individ-
ual states or other primacy agencies* may issue variances to
the TTHM rule. The available treatment methods are discussed
in a later section of this guidance.
The underlying objective of the regulation is to provide
public drinking water with fewer potential chemical health
hazards while ensuring continued protection against pathogenic
microorganisms. The purposes of this document are to provide
guidance to assist EPA Regional offices, individual states
and affected systems in their implementation of the TTHM
regulation, and to help ensure that actions taken toward
implementation will be consistent. This document is purely
advisory in nature and is meant to supplement the regulation.
Any discussion of definitive requirements, i.e., actions which
"must" be taken, should be evaluated in light of the applicable
promulgated regulations.
Hereinafter, the term "primacy agency" will be used to describe
the entity possessing primary enforcement authority under the
Safe Drinking Water Act, either individual state regulatory
agencies or (in those states which have not accepted primacy)
EPA.
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EFFECTIVE DATES OF THE MCL, MONITORING, REPORTING REQUIREMENTS
To facilitate coordination with other program requirements
of the NIPDWR, the first quarter of required THM monitoring
for systems serving over 75,000 ended on March 31, 1981,
and the effective MCL date for the first annual running
average ended on December 31, 1981. Similarly, for systems
serving between 10,000 and 75,000, the first quarter of
required THM monitoring will end on March 31, 1983 and
the effective date for the MCL will be December 31, 1983.
In the promulgated regulations the effective MCL dates
were November 29, 1981, and November 29, 1983, for the
respective system .sizes. This would require the running
annual average to be calculated from quarters ending February
28, May 31, August 31 and November 29. For purposes of
convenience to state programs, for consistency with all
previous regulations and for workability with the Model
State Information System (MSIS), and the Federal Reporting
Data System (FRDS) to be discussed later in this guidance,
the quarters will now end on March 31, June 30, September
30 and December 31.
In the promulgated regulation the quarterly averages were
required to be reported to the state within 30 days of
the system's receipt of such results. For consistency
with reporting requirements listed in Section 141.31 as
amended on August 27, 1980 in 45 F.R. 57343, TTHM quarterly
averages will be reported to the state within (a) the first
10 days of the month following the month in which the system
received its results or (b) if the required monitoring
period is stipulated otherwise by the primacy agency, within
the first ten days following the end of that period during
which the system received its results.
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MONITORING FOR TTHMS
Trihalomethanes Analysis (see 40 CFR 141.30(e))
Measurements must be made in accordance with EPA Method
501.1, "The Analysis of Trihalomethanes in Finished Waters by
the Purge and Trap Method", with Method 501.2, "The Analysis of
Trihalomethanes in Drinking Water by Liquid-Liquid Extraction",
with Method 501.3, "Measurement of Trihalomethanes in Drinking
Water with Gas Chromatography/Mass Spectrometry and Selected
Ion Monitoring" or with EPA Method 510.1, "The Determination
of the Maximum Total Trihalomethane Potential". (Methods
501.1, 501.2, 501.3, and 510.1 are available from the
Environmental Monitoring and Support Laboratory (EMSL) in
Cincinnati, Ohio). The Office of Drinking Water, Technical
Support Division in conduction with the American Water Works
Association has prepared a four part audio-visual program
detailing THM sampling and analysis consistent with these
methods. This program is available for loan on 3/4 inch
U-Matic and 1/2 inch VHS video tape, as well as 16 mm film.
For further information contact: Mr. Steven Merritt, Audio-
Visual Library, U.S. Environmental Protection Agency, 26 W.
St. Clair Street, Cincinnati, Ohio 45268.
MTP (Maximum Total Trihalomethane Potential)
The MTP determination attempts to maximize the formation
of THMs such that the test results might be indicative
of how high the TTHM concentration in the distribution
system might become under conditions favoring TTHM formation.
It may be used by systems employing ground water sources
to demonstrate the appropriateness of the reduced monitoring
requirements (discussed below) allowed under the TTHM regulations
The MTP determination has two parts: (1) a 7-day terminal THM
measurement under conditions of simple storage of a distribu-
tion sample at 25°C in the presence of a disinfectant residual,
and, (2) if the requirement for a disinfectant residual
is not met at the end of the storage period, EPA Method
510.1 is performed on a fresh sample.
Method 510.1 is designed to be a reasonable (but high)
estimate of a terminal THM value for ground water systems.
Because Method 510.1 is applied only when a disinfectant
residual is not present after performing the first part
of the MTP determination (simple sample storage and analysis),
its purpose is to measure precursors in those systems exhibiting
a disinfectant demand higher than the disinfectant dose
added at the treatment plant. Such systems have THM potentials
that may often be higher than demonstrated by instantaneous
THM monitoring in the distribution system, and thus are
those most likely to exceed the MCL with changes in
disinfection practice.
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The water sample used for this determination should be
taken from a point in the distribution system that reflects
maximum residence time. Procedures for sample collection
and handling are given in Methods 501.1 and 501.2. No
reducing agent is added at the time of sample collection
to stop the chemical reaction that produces THMs. The
intent is to promote higher THM formation than ever reasonably
would be expected in the distribution system. Four experimental
parameters affecting maximum THM production are: pH, temper-
ature, reaction time and the presence of a disinfectant
residual. These parameters are dealt with as follows:
Measure the concentration of the disinfectant
residual at the selected sampling point. Proceed
only if the disinfectant residual concentration
is greater than 0.2 mg/1. Collect triplicate
40 ml water samples at the pH prevailing at the
time of sampling, and prepare a method blank*
according to Methods 501.1 and 501.2. Seal and
store these samples together for 7 days at 25°C
or above. After this time period, open one of
the sample containers and check for disinfectant
residual. "Absence" of a disinfectant residual
invalidates the sample for further analysis.
Residual concentrations less than 0.2 mg/1 should
be considered "absent" to account for possible
analytical error. Once a disinfectant residual
has been demonstrated, open another of the sealed
samples and determine total THM concentrations
using either of the analytical methods.
In the case of sample invalidation because of disinfectant
residual depletion, additional samples should be taken
and the analysis should proceed according to method 510.1.
In this method chlorine is added to provide an initial
concentration of 5 mg/1 and the solution is buffered at
a pH of 9.D to 9.5 prior to incubation at 25°C or above
for 7 days. The high pH and temperature, and long incubation
time will produce a higher THM formation than is to be
expected in the distribution system, which is the main
objective of the test. Systems which can demonstrate an MTP
value of less than 0.10 mg/1 under experimental conditions
favoring TTHM formation are prime candidates for reduced
monitori ng.
For greater discussion of a method blank, see Section 6.4.9
of Method 501.1 or Section 6.4.10 of Method 501.2
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Reduced Monitoring Requirements (see 40 CFR 141.30(b)-(c))
(1) Surface Water Systems
Systems with any portion of their source being surface waters
are required to monitor a minimum of four samples per quarter
per plant. After one year of compliance-data monitoring, a
system may request that the primacy agency allow a reduced
monitoring frequency of no less than one TTHM sample per
quarter, taken at a point in the distribution system that
reflects the maximum residence time of the water served.*
If the system has only one source water, but more than one
treatment plant, the composite system may be allowed to reduce
its monitoring after one year to a minimum of one sample per
quarter per plant at the point reflecting maximum residence time,
If treatment plants within a system receive their water from
different surface sources the system should not reduce its
monitoring to less than one TTHM analysis per plant per
quarter at the point reflecting maximum residence time- If
one of the sources to the system is ground water, the primacy
agency may find it appropriate to reduce the required samples
for the treatment plant receiving the ground water (not the
entire system) to one MTP sample per year. In multiple source
systems it may not be possible to determine maximum residence
time sampling points for the different source waters. In such
cases it is appropriate to measure one quarterly terminal TTHM
value for the finished water from each treatment plant receiving
a different source water to fulfill the minimum monitoring
requirements. Terminal TTHM is defined according to the
conditions of the system, i.e., the TTHM determined after
incubation for a period and temperature equivalent to those at
the maximum residence time of the distribution system. (8)
The decision to reduce monitoring frequency must be made by
the primacy agency on a case-by-case basis and should take
into account monitoring data, quality and stability of the
source water, and the type of treatment. The following are
recommended guidelines for reducing monitoring requirements
for surface water systems:
If the state is conducting the THM analysis as a service
to the system there is no need for such a request. The
state that is doing the THM analysis can make the decision
on when reduced monitoring can be applied to the specific
system.
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(a) The instantaneous TTHM determination in
the distribution system should never be
greater than 0.10 mg/1. The system should
demonstrate that the instantaneous TTHM
concentration is less than 0.10 mg/1 when
maximum TTHM formation is likely to occur
(i.e., during periods of highest TOG, pH
and temperature).
(b) As a worst-case example, systems can make
MTP determinations during periods of highest
expected THM formation. Systems with less
than 0.10 mg/1 MTP under such conditions are
prime candidates for reduced monitoring frequency
while those with greater than 0.10 mg/1 MTP are
not necessarily excluded from reduced monitoring.
(c) The source water should be relatively stable
in regard to TOC, pH, turbidity and temperature.
If these parameters fluctuate greatly, the
system should demonstrate, at least with
quarterly monitoring, that this does not
significantly affect the variability of
the TTHM levels at different times of the
year. The significance of TTHM variability
depends on the annual TTHM running average;
i.e., as the value of the annual running
average decreases, the percent scatter
of TTHMs becomes less important since the
MCL will not be approached.
(d) The treatment process should remain relatively
constant throughout the year. If not, the
system should demonstrate, at least through
quarterly monitoring, that TTHM levels in
the distribution system will not vary signifi-
cantly as the treatment process changes, e.g.,
TTHMs must be monitored in the distribution system
before and after such changes are made.
(e) Systems using chloramines for residual disinfec-
tion will have minimized further formation
of THMs and will have less THM variation
in their distribution systems; therefore,
they should be considered prime candidates for
reduced monitoring.
(f) The systems should demonstrate that reduced
monitoring will take place during periods
and at locations reflecting maximum THMs
in the distribution system.
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The primacy agency should specify the reduced monitoring
permitted to the system. Should the system experience an
important change in either its source of water or its treat-
ment program, it must immediately reinstitute the four samples
per quarter monitoring initially required. The system must
continue on that program for at least one year and the sampling
frequency should not be reduced until the data baseline is
re-established and the primacy agency concurs with any reduction.
Treatment changes that could potentially increase THM
formation in the distribution system should be considered
important. Examples of this include increasing the pH for
corrosion control, adopting pre-chlorination, increasing the
disinfection dosage, changing the coagulant type and/or
decreasing its dosage for purposes other than THM control,
or changing from a chloramine or chlorine dioxide residual
to one of free chlorine. TTHM levels obtained under reduced
monitoring should reflect maximum rather than average concentra-
tions within the system. These data should be used to
demonstrate compliance but are not intended to demonstrate non-
compliance. Rather, such data should be used for determining
whether the required number of samples (as designated by the
primacy agency) have been taken and whether that system may
remain under the reduced monitoring program. If any result
obtained under a reduced monitoring program ever exceeds 0.10
mg/1, then that result should be used only as a trigger to
require that system to return to the standard frequency. The
original sampling requirements must be immediately reinstated
if any THM result (under a reduced monitoring protocol)
exceeds 0.10 mg.1 and is confirmed by at least one check
sample taken promptly after the results of the first analysis
are received. In such a case, the result which triggered the
return would not be used in any calculations for compliance
determination and would, in essence, be discarded. If the
value of the check sample is below 0.10 mg/1, prompt additional
sampling and a quality control check by the laboratory performing
the analysis should be conducted in order that the primacy
agency may determine if reduced monitoring is still appropriate.
A synopsis of the decision-making process for reduced monitoring
in surface water systems is shown in Figure 1.
(2) Ground Water Systems
Ground water systems generally have lower and mor^ consistent
precursor content than surface water systems. The regulation
thus allows monitoring requirements for systems exclusively
using ground water to be reduced to a minimum of one maximum
total trihalomethane potential (MTP) test per year, for each
aquifer contained in the system, taken at a point in the
distribution system reflecting maximum residence time. In
multiple aquifer systems it may not be possible to determine
the points of maximum residence time. In such cases it may be
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FIGURE 1
CONSIDERATIONS FOR REDUCED MONITORING REQUIREMENTS
SURFACE WATER SYSTEMS
The minimum monitoring requirement is four samples per quarter
per plant. Partially reduced monitoring requirements may be
appropriate in certain cases. Upon written request from the
public water system, primacy agencies may reduce the requirements
through consideration of appropriate data as follows:
SURFACE WATER SYSTEM
FOUR SAMPLES PER QUARTER
FOR THM
ONE YEAR OF DATA:
TTHMs CONSISTENTLY
BELOW 0.10 MG/L
CHANGE IN
TREATMENT
OR SOURCE
V
STATE JUDGEMENT ON
REDUCED MONITORING:
MINIMUM IS ONE SAMPLE
PER QUARTER FOR TTHM
TTHM > 0.10 MG/L
FACTORS FOR CONSIDERATION:
o Monitoring Data, MTP, TTHM, TOC
o Quality and Stability of Source Water
o Type of Treatment
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appropriate to sample for MTP at the finished water of
gj_cj^ £lant. Systems using multiple wells drawing water from
a single aquifer may, with primacy agency approval, be
considered as one treatment plant in regard to monitoring
requirements. In order to immediately reduce monitoring
requirements to the minimum, the system should provide a
data base substantiating that the MTP is less than 0.10 mg/1
during the period of maximum TTHM formation and/or when TOC
concentrations are highest.
If a system under the minimum monitoring requirements changes
its source water or treatment program (i.e., a treatment
change that could increase THM formation as previously
discussed) it must immediately sample to determine whether
continued reduced monitoring is appropriate. If the MTP
is ever greater than 0.10 mg/1 and such results are confirmed
by a check sample taken promptly after the results of the
original sample are received, the system must immediately
begin taking and analyzing four samples per quarter per
year for one full year. If the check sample is less than
0.10 mg/1, additional monitoring and laboratory quality
control checks should be conducted before the primacy agency
determines if reduced monitoring can be continued. As
previously discussed, TTHM levels obtained during reduced
monitoring will reflect maximum concentrations within the
system rather than average conditions and are intended
to demonstrate compliance, not demonstrate non-compliance.
Figure 2 is a synopsis of the deci si on process for reduced
monitoring in ground water systems.
When to Monitor
Quarterly monitoring periods will end on March 31, June
30, September 30 and December 31 (see discussion on effective
dates of the MCL, monitoring and reporting requirements).
Monitoring within each quarter should take place during the
same month (i.e., first, second or third) of each quarter
to ensure representation of seasonal effects.
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FIGURE 2
CONSIDERATIONS FOR REDUCED MONITORING REQUIREMENTS
GROUNDWATER SYSTEMS
The minimum monitoring requirement is four samples per
quarter per plant: systems using multiple wells drawing
raw water from a single aquifer may with primacy agency
approval be considered as one treatment plant. Reduced
monitoring requirements may be appropriate in certain
cases; upon written request from the public water system,
primacy agencies may reduce the requirements through
consideration of appropriate data as follows:
CHANGE IN
TREATMENT
OR SOURCE
CHANGE IN
TREATMENT
OR SOURCE
GROUNDWATER SYSTEM
SAMPIE FOR MTP
MTP>0.10 MG/L
MTP<0.10 MG/L
JUDGEMENT"
STATE JUDGEMENT ON
REDUCED MONITORING
MINIMUM : ONE SAMPIE
PER YEAR FOR MTP
FOUR SAMPLES PER QUARTER
FOR TTHM
ONE YEAR OF DATA:
TTHM CONSISTENTLY
BELOW 0.10 MG/L
CONTINUE
FOUR SAMPLES
PER QUARTER
STATE JUDGEMENT ON
REDUCED MONITORING
MINIMUM: ONE SAMPLE PER
QUARTER FOR TTHM
TTHM>0.10 MG/L
Factors for Consideration :
o Monitoring Data, MTP, TTHM, TOC
o Type of Treatment
o Quality and Stability of Source Water
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S a m p 1 ing Locations
1. Sampling locations from taps in the distribution
system should be approved by the primacy agency.
2. No more than seventy-five percent of the samples must
be collected from locations that represent the majority
of people served. The sampling sites should be separated
equally from each other in the distribution system to the
extent possible.
3. At least twenty-five percent of the samples must be
collected from a location(s) reflecting maximum residence
time. This must be from a remote point(s) in the dis-
tribution system through which there is active water
passage, i.e., not a dead end.
4. In cases of more than one water source and/or treatment
plant in a system, sampling points should be determined
so as to be quantitatively and qualitatively representa-
tive of each water source.
5. For each treatment plant in a system, there must be
at least four sampling locations. Upon primacy agency
approval, water from a single aquifer may be considered
a single treatment plant for determining the minimum
number of samples required.
6. In situations where a system has two separate plants,
both drawing water from the same source, via the same
intake, the primacy agency may elect to treat the plants
as one for the purpose of determining the number of TTHM
samples required to be taken, j_f the two plants:
a) have like treatment processes, and
b) serve the same distribution system or serve distribu-
tion networks with similar maximum residence times.
Primacy agencies should use extreme care in allowing this
sampling merger and should do so only after the two plants
demonstrate:
a) similar analytical results, and
b) separate compliance with the 0.10 mg/1 MCL.
7. The primacy agency should determine whether booster
chlorination stations should be considered separate
treatment plants within a system. If booster chlorina-
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tion stations are not considered a treatment plant,
then it is recommended that the number of sampling
locations beyond such chlorination points be based on
population density throughout the distribution system.
The sample(s) reflecting maximum residence time must be
taken in the extremity of the distribution system beyond
such chlorination points.
8. Sampling for trihalomethanes should be a continuing
program. Once sample locations have been established
for an individual water system, they should remain the
same unless there is a substantial reason for changing
(e.g., change in water source and/or in the entry
point to the distribution system). In such cases the
primacy agency must be notified. Sample collection
locations should therefore be selected carefully such
that year-round access is assured while inconvenience
to the customer is minimized.
9. Fire hydrants must not be used as sampling points.
Samples from a hydrant may not provide "representative"
water quality.
10. All samples must be representative of the water in
the water main and not "dead" water from the building
or water service piping. Sampling points at buildings
having large service lines and only periodic use (e.g.,
large churches and department stores) should be avoided.
11. Samples should not be collected at buildings having
their own water softener or purifier unless the faucet
used for sampling is not connected to the water conditioner,
Surveillance for Other Organic Compounds
It is recommended that systems ask the certified laboratories
conducting their THM analysis also to be alert for other
peaks on their chromatograms. The Office of Drinking Water
strongly encourages all systems to examine all of the data
available from their THM analysis. In addition to demonstrating
compliance with the MCL, a typical THM analysis can indicate
the presence of other potentially serious contaminants.
Chromatographic peaks which appear with significant amplitude
and consistency reflect other volatile organic compounds
which should be identified and reported so that the significance
of the contaminant(s) can be evaluated.
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DETERMINATION OF COMPLIANCE WITH THE MCL (see 40 CFR 141.30(d))
1. Sampling from two types of locations are required:
at least 25 percent from those reflecting
maximum residence time (type "A") and no
more than 75 percent from those reflecting
the quality of water consumed by the majority
of customers (type "B").
For purposes of compliance, the system must determine
its annual running average from quarterly averages
having the above distribution. If more than
four samples are taken in a quarter, and they
are not a multiple of four and are not in accord
with the above distribution, the following formula
must be used for determining the quarterly average:
(average of type "A" samples) X 0.25
+ (average of type "B" samples) X 0.75
= quarterly average.
2. For systems with more than one treatment plant,
the quarterly average, representative of each
treatment plant, should be determined separately.
The quarterly average for the entire system must
be calculated by weighting the averages from
each of the treatment plants (total number of
treatment plants = n) as follows:
(quarterly average for samples representing treatment plant 1)
X (fraction of flow* into system from plant 1)
+ (quarterly average for samples representing treatment plant 2)
X (fraction of flow* into system from plant 2) ...
+...(quarterly average for samples representing treatment plant n)
X (fraction of flow* into system from plant n)
= quarterly average for system.
For purposes of this determination only, flow is defined as
the average daily flow for the subject treatment plant during
the subject compliance period.
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Although not required by the regulation, the
annual running average representative of each
treatment plant within the system should also
be reported to the primacy agency. Systems are
encouraged to ensure that each treatment plant
within the system distributes water within the
limits of the MCL. Because of mixing, obtaining
samples from a common distribution system that
uniquely represents each of the different treatment
plants feeding into the system may not be possible.
In such cases terminal THM determinations from the
finished water of each treatment plant may be useful
for making judgements as to how best to achieve
compliance with the TTHM MCL (as discussed in the
section on evaluating treatment options). Terminal
THM is the measured trihalomethane concentration
after the reaction between precursors and free
chlorine has been allowed to continue in a sealed
container at the temperature and for the maximum
residence time of that water in the distribution
system (8).
For calculating the annual running average, each
quarterly average must be given equal weight
regardless of the number of samples taken per
quarter.
The annual running average must be computed to
two significant figures. If this is greater
than 0.10 mg/1 (i.e., 0.11 or above), the system
is out of compliance and must follow the public
notification procedures, a summary of which is
contained in the Appendix. Rounding-off numbers
shall be in accordance with Water Supply Guidance
No. 72 (see Appendix).
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CONSECUTIVE SYSTEMS
A system purchasing water in whole or in part from another
system is considered a "consecutive system". Such systems
having populations greater than 10,000 are required to
meet the MCL; however, it may not be reasonable to consider
each consecutive system as a separate system in regard
to monitoring requirements. If TTHM levels at the most
remote points of the combined systems are well below the
MCL, the primacy agency may determine it appropriate
to permit reduced monitoring in the preceeding systems
having shorter residence times.
If the preceeding system exceeds the MCL, the consecutive
system is also likely to do so and it is then in the mutual
best interest for the two or more systems to work together
so that all will be in compliance with the MCL. Without
such mutual co-operation, it would be possible for a treatment
change in the main system to reduce the parent's average TTHM
levels below 0.10 mg/1 while the consecutive system remained
out of compliance. The parent system should, at least, make
the appropriate modifications to reduce the THM concentration
below 0.10 mg/1 at the point where the consecutive system
receives the water. In cases where the preceding system
has average TTHMs just below 0.10 mg/1 within its distribu-
tion system and is reluctant to make treatment changes
in concern for the system receiving its water, several
treatment options for the consecutive system exist to stop
further THM formation. These include the addition of ammonia
to combine with any remaining free chlorine and provide
a chloramine residual, or, in lieu of additional chlorination
(if that residual has been exhausted), the addition of chlorine
dioxide or other alternate disinfectants. The use of chlor-
amines should be considered only after a careful analysis
of all aspects of the chlorami nation technology, including
the potential health risks associated with its use. Extensive
discussions of these issues are contained both later in this
document and in several references (4, 7, 16, 22-24).
A combination of parent and consecutive systems wherein the
total population served is above 10,000 while the individual
system populations are each below 10,000 is an anomalous
situation but one not to be easily dismissed. Although the
regulation does not requi re compliance by any of such affected
systems, the primacy agency may (after suitable study)
determine that compliance by one or more of those systems is
desirable. Such an extension should be pursued only after
the overriding concern for continual maintenance of suitable
microbiological quality at all points in the combined systems
has been satisfied.
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THE ROLE OF MSIS
The Model State Information System (MSIS) will implement
automatic determination of compliance with trihalomethane
(THM) sampling requirements for the compliance quarter
ending March, 1981. Each calendar quarter, violations will
be determined for failure to sample by public water systems
that serve at least 75,000 people and employ a disinfection
agent, or for which trihalomethane monitoring is required
under federal or state regulation. Within constraints
set forth in the regulation, the state may specify through
MSIS, the total number of TTHM samples required from a
specified system, annual reduced monitoring frequency for
a specified system, or the total number of treatment plants
from which a minimum of four samples per plant per quarter
will be required. Each sample must be identified as represen-
tative either of the distribution system or of the maximum
residence time of water in the system. MSIS will identify
failure to adhere to the sampling ratio of 25 percent to
75 percent of the number of required samples representing,
respectively, the maximum and average residence times of
water in the distribution system. For example, a system
would not be in violation if it conducts more than the
minimum number of sample analyses as long as it adheres to
the criterion of 25% of samples representing maximum residence
time.
In determination of trihalomethane contamination, MSIS will
appropriately apply factors of 0.25 and 0.75, respectively,
to single sample analysis results in calculating the sum of 4
equally weighted quarterly averages that will be used to
determine compliance with the MCL. Quarterly averages
calculated by MSIS do not necessarily reflect the percentage
of total flow from individual treatment plants. For each Public
Water Supply, MSIS will accept a previously calculated,
weighted average of all analysis results per quarter, for use
in annual contamination determination.
-16-
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MICROBIOLOGICAL CONCERNS AND SAFEGUARDS (see 40 CFR 141.30(f))
Systems should take specific precautionary measures to
ensure that the microbiological integrity of their water
is not compromised as a result of treatment modifications
to reduce THM levels. The THM regulations require that
before a water system makes a significant modification
to its existing treatment process, for the purposes of
achieving compliance with the THM MCL, the system must
submit to and receive approval from the primacy agency a
plan describing its projected course of action. This plan
must indicate both the proposed treatment modifications
and the safeguards intended to be taken to protect the
microbiological quality of the drinking water. Figure 3
illustrates a recommended course of action for providing
adequate safeguards while meeting the THM MCL.
Modifications that might be considered significant are
those whose effects on microbiological quality cannot be
predicted. For example:
o a change in the type, dosage, point of applica-
tion or contact time of the disinfectant;
o a change in or blending of the source water;
o the installation of an open finished water
reservoir; or,
o the addition of an adsorbent (e.g., activated
carbon) in the treatment chain.
If after consultation with the system, the primacy
agency determines that the proposed modifications are
significant (i.e., may pose an increased potential human
health risk), then the system must submit an action plan
which contains at least the specific provisions detailed
below:
Evaluation of System for Sanitary Defects
The system's action plan should include provision for a thorough
sanitary survey of the entire system (source, treatment
train and distribution system) before any treatment changes
for THM control are formally proposed. The purpose of the
survey is to collect information to determine the capability
of a system to continuously provide water that uoth meets the
NIPDWR and is adequately protective of public health. Any
sanitary defect or unsound treatment practice must be identified
and corrected before THM control practices are initiated.
-17-
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Figure 3
RECOMMENDED PROCEDURE FOR ENSURING
MICROBIOLOGICAL SAFETY OF DRINKING HATER
THM
SAMPLE
ANALYSIS
00
YES
ACTION PLAN/STATE APPROVAL
0 SANITARY SURVEY
0 TREATMENT OPTIONS
0 MICROBIAL MONITORING
BASELINE MONITORING
6 MONTHS BEFORE
TREATMENT CHANGE
TREATMENT CHANGE
MONITOR 1 YEAR
AFTER CHANGE
NO
W1
STATE/SYSTEM
NEW MODIFICATION
-------
There are many excellent sanitary survey protocols available
from e.g., the Conference of State Sanitary Engineers or the
American Water Works Association (AWWA). The survey protocol
should, as a minimum, include the following elements:
(a) an examination of the source water and the
potential for its pollution. For surface
water sources, attention should be directed
to the location of wastewater treatment
plants, storm water drains and sewer outfalls,
and characteristics of the watershed drainage
area. For ground water sources inspection
should include the drainage area and habitation,
local geology, nature of soil and rock strata,
slope of the water table and potential sources
of pollution.
(b) an examination of the complete treatment
and distribution system including the adequacy
of each unit process, the sanitary safety
of the storage and distribution facilities
(including all pump stations) and the potential
for cross-connection contamination.
(c) an evaluation of the previous 12 months
of microbiological records and chemical
analyses on water from the source, the treatment
plant and the distribution system.
(d) an evaluation of operating plans and records
for present capacity, demand and production.
(e) a review of the training, experience and
capabilities of the personnel.
(f) a review of the laboratory equipment and
procedures, including the qualifications
of the laboratory personnel.
(g) an examination of system compliance for
federal, state and local regulations and
plumbing codes.
(h) a summary and analysis of all facts
pertinent to potential or existent health
hazards within the system from the source
to the consumer's tap.
-19-
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The person making the survey should have education in basic
sanitary sciences and have experience in the concerns mentioned
above. A survey report, summarizing the above findings,
including maps and sketches where appropriate, should be
submitted with the system's action plan for THM control.
Evaluation of Treatment Options
Following the sanitary survey and correction of any sanitary
defects, the system should develop a plan for optimizing
existing unit processes for THM control; this should be
submitted to the primacy agency as part of the action plan.
The plan should provide a comprehensive evaluation of any
existing unit processes for such parameters as precursor
removal, disinfection efficiency and formation of THMs.
Appropriate THM control options can be assessed only with a
fundamental and thorough knowledge of the prevailing efficiency
of the entire treatment process. A THM profile through the
treatment plant and distribution system should be developed
to show where control can be exercised (2, 8).
Selection of the most appropriate treatment options will
be influenced by their apparent effectiveness for lowering
THM concentration, the microbiological quality of the raw
water, raw and finished water quality and costs. Several
treatment options may need to be considered before the
optimum can be selected.
Baseline Water Quality Survey
The system's action plan should also include a detailed
description of its baseline monitoring survey. The purpose
of this survey is to detect changes in the quality of the
water within the system, resulting from treatment modifi-
cations, that may lead to increased public health risk.
Total coliforms are the most commonly used indicators for the
microbiological quality of drinking water and are essential
to this baseline survey- This use, however, needs to be
supplemented with the use of other microbiological and
chemical parameters to ensure that subtle deteriorations in
water quality and attendant increased risk to public health
do not remain undetected. For example, the lack of coliform
recovery by itself does not guarantee an absence of pathogens
(9-11). Coliforms are less resistant to environmental stress
and disinfection than some pathogenic viruses and bacteria.
More of the pathogenic organisms either may survive the
altered treatment process, thereby directly increasing the
public health risk, or may multiply in finished waters leading
to slime deposits, tubercule formation and interference
with coliform determination (11).
-20-
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The water quality should be monitored before and after
the THM treatment modifications are implemented. Over
long periods of time changes in water quality can be masked
by normal seasonal variations. Therefore, the survey should
begin a minimum of 6 months before the treatment modification
(including at least the warmest water month) and continue
for 1 year after the treatment modification. Changes in
water quality due to normal seasonal variations, volume
of water storage or stream flow, and unusual weather conditions
can be important to the interpretation of data. The influence
of these effects should be evaluated before decisions are
reached concerning potentially detrimental changes in the
quality of the water.
(1) Water Quality Parameters
Parameters which may aid in evaluating both the impact of THM
controls upon and the continued optimum microbiological
quality of finished drinking water include:
0 total coliforms,
0 standard plate count incubated for two (2) days at
both 35° C and 20° C,
0 heterotrophic plate count incubated for at least five (5)
days at environmental temperature (e.g., 20° C), or
at 28° C using R-2A media with 7-day incubation (see
Appendix for media preparation),
0 disinfectant residual,
0 enteric viruses in systems with grossly polluted
source waters,
0 turbidity ,
0 total fecal coliforms,
0 fecal streptococci,
0 orthophosphate,
0 ammonia nitrogen,
0 total organic carbon,
0 pH, and
0 temperature.
-21-
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A primacy agency should decide which of the above (or additional)
parameters are appropriate for inclusion in the system's
baseline survey, given the local conditions at specific
supplies (see 40 CFR 141.30 (f)). The approved plan should
require the maintenance of an active disinfectant residual
throughout the distribution system at all times both during
and after any proposed treatment modifications. Required
monitoring should be sufficient to demonstrate the presence
of this active residual.
Analytical procedures appropriate to the microbiological
parameters listed above can be found in the 15th edition of
Standard Methods for the Examination of Water and Wastewater
(12), or Microbiological Methods for Monitoring the Environment
(13). Analytical procedures appropriate to the physical and
chemical parameters listed above can be found in Standard
Methods for the Examination of Water and Wastewater (12),
Methods for Chemical Analysis of Water and Wastes (14), and
the Annual Book of ASTM Standards, Part 31 Water (15).
Those methods which are recommended are shown in Table 1. A
discussion of certain water quality parameters follow:
o Bacteriological Quality
The presence of total coliforms in finished water indicates
potential penetration of the treatment barrier by pathogenic
bacteria. These organisms should not be present at any time
in the treatment plant effluent or in the distribution system.
If any such organisms are present, then this potential problem
should be identified and corrected.
The standard plate count at 35°C is an indicator for the
potential presence of opportunistic pathogens, such as certain
strains of Pseudomonas and Flavobacterium, and organisms
which can interfere in the total coliform test (23). The
standard plate count at the lower temperature accommodates
slower growing bacteria that are adapted to the aquatic
environment; this is particularly suited for indicating
bacterial growth within the distribution system. To obtain
maximum sensitivity, optimum temperatures and incubation
times should be determined. Standard plate counts taken
before and after alterations in the disinfection process
can be useful in detecting changes in bacteriocidal effective-
ness.
-22-
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Table 1 -- Recommended Chemical and Physical Methods
Parameter
Methodology
£PA(14)
SM(12)
ASTM(15)
Turbi dity
PH
Temperature
TOC
Ammonia
Nitrogen
Orthophos-
phate
Nephelometric
Potentiometric
Thermometer
Combustion or
Oxidation
Low Level TOC
For drinking water,
need not di still if
using nessleri zati on ,
the electrode
or automated phenate.
However, must concen-
trate by distilling
if using titration. **
180.1 214A
150.1 423
212
415.1 505*
(See appendix)
350.3
350.1
350.2
The ascorbic acid method
automated or 365.1
manual or 365.2
manual two- reagent 365.3
417B
417E
417F
417D
424G
424F
D1293-78 A
or B
D2579-78(A)"
D1426-79 (A)
01426-79 (D)
01426-79 (C)
D515-78 (A)
This method's sensitivity is approximately 1.0 mg/1. Therefore, it may
not be appropriate for use by all systems in all situations.
**
The titrimetric method is used primarily for measuring relatively high
NH3-N concentrations (i.e., above 5.0 mg/1) and this may not be appropriate
for use by all systems in all situations.
-23-
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A new medium, R-2A, has been developed by EPA which yields
a significantly greater number of bacterial colonies and
colony types than SPC agar. Consideration should be given
to using R-2A agar in lieu of SPC agar for lower temperature
incubation. The investigators suggest 28°C incubation for
7 days. R-2A agar is available as a commercial dehydrated
medium product or can be prepared from the formulation that
appears in the Appendix.
o Disinfectant Residual
A free chlorine residual, if used, should be greater than or
equal to 0.2 mg/1 at all times and places in the distribution
system. A chloramine residual, if used, should be kept
above 0.5 mg/1. These residuals should be maintained to
prevent microbial growth and to minimize the risk of potential
contamination from cross connection and back siphonage.
Experience indicates coliform regrowth in the distribution
system may occur during warm periods at free chlorine residuals
of 0.1 mg/1 or less (16).
If chlorine dioxide is used, the total oxidant (i.e.,
chlorine dioxide, chlorite and chlorate) residual should be
kept below 1.0 mg/1; this is because of concern for potential
hematological effects (from chlorine dioxide and chlorite).
Chlorine dioxide residuals alone should be kept above 0.2
mg/1 to provide adequate protection in the distribution
system. Further discussion of these issues is contained in
Water Supply Guidance # 74, located in the Appendix.
o Enteric Viruses
At the present, there are practical limitations with the
analytical methods used to determine enteric virus presence
in drinking water. Therefore, monitoring for viral breakthrough
should be considered optional provided a sanitary inspection
of water plant records indicates conventional water treatment
processes are functioning properly. Where source waters
are grossly polluted (excess of 20,000 total coliform or
2,000 fecal coliforms per 100 ml) virus monitoring of the
water treatment processes involved in modifications is
recommended as a part of the baseline study.
EPA is currently attempting to develop a low cost effective
method, using coliphage, for indicating treatment effective-
ness in reducing the number of enteric viruses. Method
develoment and testing is now underway. It is anticipated
that this method, when fully developed, will be a more
sensitive analytic tool than those presently available.
EPA will disseminate this information as soon as it becomes
available (31).
-24-
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o Turbidity, Temperature, pH
Increases in turbidity due to a treatment system modification
are not acceptable because of potential increases in competition
for available oxidant from other oxidizable materials, which
could reduce disinfection effectiveness (28). Optimum
precursor and turbidity removal should be attempted without
increasing the pH before the point of disinfection. If the
pH is significantly lowered either to reduce THM formation
or improve precursor removal in a clarification process,
this might, however, significantly increase the corrosivity
of the water. The potential of such trade-offs should
be considered before such treatment changes are made.
Temperature and pH affect THM formation, disinfection effective-
ness and microbial activity. When the water is warmest,
microbial activity is potentially at a maximum. However,
disinfection effectivess is then also at a maximum (at
a minimum when water is coldest). Free chlorine and chloramines
are significantly more biocidal at lower pH values. Apparent
anomalies in the microbial data base might thus be explained
by irregularities in temperature and pH changes within
the system.
o Nutrients
Organic carbon, measured as TOC, ammonia nitrogen and ortho-
phosphate serve as nutrients for microorganisms, including
those that cause disease; they also represent the products
of microbial activity and cell decomposition. The presence
of these nutrients can stimulate as well as indicate microbial
activity.
Adequate disinfection would be suggested by the maintenance
of low bacterial counts in the distribution system during
periods of highest nutrient concentration (e.g., during
algal blooms or turnover in lakes and large reservoirs,
or from agricultural runoff or upstream discharge). In
cases where systems use either, or both, ammonia or phosphate
in their treatment processes, monitoring for nutrient concent-
rations is probably inappropriate.
(2) Monitoring Locations and Frequency
The purpose of monitoring for the above water quality parameters
is to develop a baseline by which possible changes in treated
water quality can be determined subsequent to the installation
of TTHM control practices. This monitoring should be in
addition to or in conjunction with that conducted to satisfy
minimum sampling requirements specified in the NIPDWR.
-25-
-------
Weekly analysis for total coliforms, standard plate counts
and disinfectant residuals should be conducted for periods
of 6 months before (including the warmest water month)
and 12 months after the treatment change. Samples should
be collected from the raw water, at a point in the treatment
plant just before final disinfection, from the treatment
plant effluent and from the ends of the distribution system.
During periods of abnormal increases in source water pollution
of other raw water quality discontinuities, daily monitoring
at the above sampling points may be appropriate.
Long term microbiological effects of treatment modifications
will be observed initially in the low-flow or dead-end sections
of the distribution network. These locations frequently have
accumulated sediments where waterborne organisms can become
established. Sampling of dead-end sections should be done
on a weekly basis, rotating site locations so as to include
all major dead-ends during the warm season.
Disinfectant residuals should be measured at the treatment
plant effluent and at all sample points in the distribution
system.
(3) Interpretation of Data
Information gathered during the pre- and post-treatment
phases is designed to detect subtle changes in water quality
that are related to microbial survival and activity within
the system. This information should be used in conjunction
with the sanitary survey and the analysis of the existing
treatment train to determine whether the public health
is at risk due to microbial penetration of some portion
of the treatment barrier. In comparing data obtained in
the pre- and post-treatment studies, any deterioration
of water quality from test sites within the treatment plant
and/or distribution system should be carefully evaluated.
-26-
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APPROACHES TO CONTROLLING TTHMs
The production of safe drinking water in the United States
traditionally has been based on the multi-barrier concept.
This concept requires that water be taken from the best
source available, treated by appropriate unit processes to
meet applicable drinking water quality standards, disinfected
and transported to the consumer through water distribution
systems free from sanitary defects. The goal of water treat-
ment always has been, and will continue to be, the production
of drinking water free from pathogenic contamination. The
underlying principle in control of THMs is that as THM control
practices are conceived and put into practice, the water
supplied to the consumer must continue to be of optimal
microbiological quality. Such a principle is consistent with
ODW's repeatedly stated concern over the possible human health
risks associated with exposure to any disinfecting agent or
other chemical additive. ODW's consistent position has been
that the generation of excessive amounts of disinfection
by-products is to be avoided, ideally through the optimization
of existing and/or conventional unit processes such that
excessive application of any chemical oxidant is avoided.
The appropriate approach for systems to follow in controlling
THMS is described in detail in Technologies and Costs for
the Removal of Trihalomethanes from Drinking Water (29)
and fn the amendment to the TTHM implementation Fe~g u 1 a t i o n s
(48 F.R. 8406).
Those documents define three general categories of technolog-
ies for controlling THMs:
0 Group I technologies are the "Best Generally
Available Treatment Methods for Reducing
TTHMS." These techniques are each widely
recognized, relatively low cost and relatively
highly effective for controlling TTHMS.
These frequently will be the methods of choice
for affected systems attempting to comply with
the TTHM MCL (see Table 2).
0 Group II technologies are not general1y
available (as defined by statute) but may
be both available and appropriate for certain
systems in meeting the TTHM MCL (see Table 2).
The amendment also discusses the criteria by which
variances may be granted to non-compliant systems
by primacy agencies. Compliance schedules associated
with variances from the MCL may include a requirement
that affected systems examine the availability,
feasibility, cost and effectiveness (for their
particular system) of the technologies in this
Group.
-27-
-------
TABLE 2
Included in the Group I technologies are;
0 Use of chloramines as an alternate or supplemental
disinfectant or oxidant.
° Use of chlorine dioxide as an alternate or supplemental
disinfectant or oxidant.
0 Improved existing clarification for THM precursor reduction,
0 Moving the point of chlorination to reduce TTHM
formation and, where necessary, substituting for the
use of chlorine as a pre-oxidant chloramines, chlorine
dioxide or potassium permanganate.
0 Use of powdered activated carbon for TTHM precursor or
TTHM reduction seasonally or intermittently at dosages
not to exceed 10 mg/1 on an annual average basis.
Included in the Group II technologies are;
0 Introduction of off-line water storage for TTHM
precursor reduction.
0 Aeration for TTHM reduction, where geographically and
environmentally appropriate.
0 Introduction of clarification where not currently
practiced.
0 Consideration of alternative sources of raw water.
0 Use of ozone as an alternate or supplemental disinfectant
or oxidant.
Included in the Group III technologies are;
0 Granular Activated Carbon (GAC)
0 Biologically Activated Carbon (BAC)
-28-
-------
0 Group III technologies are not required to
be considered as potential solutions to a
TTHM compliance problem but may be studied
by some systems for reducing TTHMS (see
Table 2).
More detailed descriptions of each of these options and
discussion of when each might or might not be applicable
are contained in Treatment Techniques for Controlling Tri-
halomethanes in Drinking Water (2). Each technique has
advantages and disadvantages; site-specific factors will
probably affect the final treatment choice. Some specific
microbiological concerns with certain of the technologies
which should be considered by the primacy agency are
discussed below.
Improved clarification (or introduction of clarification)
to remove additional THM precursors, assuming pH is not
increased, will improve the disinfection effectiveness
of the oxidant. Waters with minimum disinfectant demand
and turbidity will promote maximum contact between pathogens
and the disinfectant. Thus improved coagulation may also
improve disinfection effectiveness. For example, the presence
of organic material has been shown to decrease the amount
of virus removed by alum or ferric chloride coagulation (17).
Shifting chlorination to a point of minimum precursor
concentration will reduce disinfectant contact time and
microbial die-off in the early stages of treatment. Thus,
greater reliance is placed on pathogen removal by coagulation,
settling, filtration and post-disinfection. Also, chlorina-
tion (with adequate contact time) is most effective in the
post-treatment phase where suspended material and disinfectant
demand is at a minimum. Field studies indicate that the
microbiological integrity of finished water (i.e., following
post-disinfection) can be maintained after shifting the
chlorination point to later in the treatment train (16).
Problems such as slime growth in settling basins, which are
often controlled by pre-chlorination, may be controlled by
alternate treatment (e.g., potassium permanganate, or chlorine
dioxide).
Chloramines as an alternate disinfectant are generally recog-
nized to be a relatively less efficient disinfectant than
free chlorine, ozone and chlorine dioxide when relative lethality
coefficients are compared on a one-to-one basis in laboratory
studies. However, in actual practice the mechanisms for chloramine
-29-
-------
disinfection are markedly different from those for free
chlorine disinfection (4,7). These statements are based
on comparison of lethality coefficients from laboratory
experiments using "clean" water (i.e., containing only
seeded microorganisms and the disinfectants in distilled
water). How actual field conditions affect the relative
biocidal efficiency of different disinfectants is a subject
of continuing investigation. Under field conditions free
chlorine, chlorine dioxide or ozone are reduced at a greater
rate than chloramines. Based upon the product of residual
concentration and contact time, the disinfectant with the
lower lethality coefficient catches up quickly in performance
relative to the disinfectant with a high lethality coefficient
at the same initial dosage (19), i.e., under long contact
times chloramines can kill the same number of microorganisms
as other oxidants. One study found that in tertiary sewage
effluents combined chlorine residuals were nearly as effective
as ozone or free available chlorine for bacterial and viral
destruction (20). The use of chloramines (with long contact
times) as the primary disinfectant (in conjunction with
adequate physical/chemical treatment) has been shown to both
provide adequate disinfection (based on coliform and standard
plate counts) and restrain bacterial growth in the distribution
system (19, 22-24). If chloramines are used as a primary dis-
infectant, then it is critical that long contact times be
maintained at the optimum chlorine-to-ammonia nitrogen ratio.
Although certain conditions may allow it, chloramines generally
have not been recommended as a primary disinfectant, i.e., used
without a preceding stronger disinfectant such as free chlorine
or chlorine dioxide. The adequacy of viral inactivation by
chloramines, even with long contact times, has been questioned.
Chloramines are recognized and accepted as a secondary disin-
fectant to provide protection in the distribution system (4).
Post-chloramine application to stop THM formation should
generally follow disinfection with free chlorine, chlorine
dioxide or an equally effective disinfection period with
ozone. High energy mixing in the contact tank may allow
shorter free chlorine contact times. Treatment systems
should demonstrate that the use of chloramines, either as
as primary or secondary disinfectant, does not create a
potential reduction in disinfection efficiency.
One recent study has raised questions on the merits of
using chloramine residual protection in the distribution
system (25). Field conditions simulated in the laboratory
suggested that a free chlorine residual was significantly
-30-
-------
more effective than a combined chlorine residual in protecting
a distribution system from contamination of sewage infiltration
In addition, free chlorine (because of its disappearance) was
shown to be a better indicator of possible sewage contamination
than chloramines.
Chlorine Dioxide as an Alternative Disinfectant - The use of
chlorine dioxide is not as widespread as that of chlorine.
As of 1977, chlorine dioxide was being used at 84 and 495
water treatment plants in the U.S. and Europe, respectively
(5). It has been used for pretreatment (taste and odor
control and removal of iron and manganese) in the U.S. and
for final disinfection in Europe. Lack of widespread application
in the U.S. was due to higher cost and more complex application
equipment and control. However, due to anticipated regulatory
action, several treatment plants have adopted chlorine dioxide
to reduce THM concentrations in their finished water (3).
Under some conditions, chlorine dioxide is a more effective
biocide than chlorine (7), and offers potentially better
protection than chlorimines against pathogen penetration of the
treatment barrier. Its usage, however, must be carefully
controlled. Chlorine dioxide breaks down in water to chlorite,
chlorate and ultimately chloride ions. Individuals having
certain enzyme deficiencies might be sensitive to these
agents; however, preliminary tests have not demonstrated
this effect. To provide a margin of safety from the possible
effect of ingested chlorine dioxide and chlorite, the concen-
tration of the total residual oxidants should be monitored
and kept below 1.0 mg/1 in the distribution system. The
previously recommended level of 0.5 mg/1 has been re-examined
and raised slightly as the result of studies reported in
1981 (30).
Daily samples for such analyses should be collected from
the effluent of the clearwell and the results should be
submitted to the primacy agency along with THM data. The
method for determining total residual oxidants (including
chlorate, which may also have a related health risk) is still
being developed. Until this is available, Methods 330.6 or
330.7 (available from the Environmental Monitoring and Support
Laboratory (EMSL) in Cincinnati, Ohio) or 411C (Standard
Methods, 15th edition) may be used for determining chlorine
dioxide and chlorite residuals; the sum of the residuals
should be less than 1.0 mg/1.
Although chlorine dioxide may not be reduced as much as
free chlorine because it does not react with ammonia, its use
as a residual disinfectant is likely to be limited because
of the recommended maximum residual level of total oxidants.
-31-
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However, optimizing the removal of reducing substances,
before the addition of chlorine dioxide as well as using
chlorine dioxide that is relatively free from traces of
chlorite and chlorate may permit Its use. Also, this will
minimize the potential formation of other disinfection by-
products having unknown health risks.
Where pre-disinfection cannot be eliminated, chlorine dioxide,
applied in low doses, may provide both adequate initial dis-
infection and good THM control (3). Subsequent addition
of chemicals to reduce residual chlorite (e.g., Fe++, sulfur
dioxide) may also be considered if chlorine dioxide is being
used for disinfection early in the treatment processes.
Free chlorine or chloramines, depending on the remaining THM
precursors, could then be used to provide the necessary
residual protection.
Ozone as an Alternate Disinfectant - As of 1977, there were
over 1,000 water treatment plants in the world using ozonation
as a unit process (5). Most of these plants are in Europe
where people tend to be extremely critical of the taste and
odor often created by chlorination. Ozone is the most powerful
oxidant that is commonly used but its residual is short
lived (7). Residual protection in the distribution system by
another disinfectant is thus essential. Because of potential
formation of undesirable by-products, application of ozone,
like the other disinfectants, should be delayed until the
maximum amount of THM precursors are removed by other unit
processes. Application of ozone in the early stages of the
treatment process could be practiced when such application
creates significant improvements in the efficiency of THM
precursor removal by other unit processes such as coagula-
tion, sedimentation, filtration or adsorption. Pilot testing
is essential for predicting performance and should precede
full-scale application, A summary on the application of
ozone for enhancing THM precursor removal, and an explanation
of the controversy over existing data is given by Rice (27).
An additional consideration is that ozonation of waters
having high TOC levels has been known, in the absence of
adequate residuals, to result in biological growth that
causes problems in distribution systems (6). In such cases,
chloramines may not be a suitable residual disinfectant.
Monitoring in the distribution system as previously discussed
is essential to determine the presence of this effect.
-32-
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Granular Activated Carbon (GAG) can serve as a valuable
adjunct to existing processes for THM precursor removal but
its performance is limited depending upon its application.
Fresh GAG can remove a high percentage of THM precursors.
However, a typical mode of operation for a GAG installation
(i.e., replacement of the sand in an existing sand filter)
may not provide adequate contact time to effect adequate
removal of THM precursors. Further, relatively frequent
regeneration or replacement of the carbon may be necessary
to sustain a high removal rate. Long-term steady state
precursor removal (15-30%), attributed to microbial activity,
is possible in bed depths of three feet (2), and this, in
conjunction with other preceeding unit processes, might lead
to its adoption by a system seeking protection from a broad
spectrum of organic contaminants. Free chlorine residuals
in water entering a GAG bed are likely to impair microbial
degradation of THM precursors and reduce GAG effectiveness.
If pre-filter disinfection cannot be eliminated, alternate
oxidants such as potassium permanganate should be considered.
The effectiveness of GAG largely depends on the quality of
the water; thus, pilot testing is essential for predicting
its performance. Standard bacterial plate counts have been
shown to increase several orders of magnitude in water passing
through GAG. This increase has been attributed to the greater
availability of organic compounds and nutrients which collect
on the carbon. Greater reliance must be placed on post-disin-
fection as a continuously effective, final treatment barrier
to GAG effluent bacterial populations prior to finished
water release into the distribution system (16).
It should be emphasized that as THM control practices are
implemented, an effective treatment barrier that provides
a safe water must be maintained. Requiring that levels
of THMs be controlled does not imply that EPA wishes the
use of free chlorine as a disinfectant be abandoned. For
example, available technologies such as changing the point
of chlorination and/or maximizing the efficiency of THM
precursor removal in an existing coagulation process, can
significantly reduce TTHM levels while maintaining the
use of free chlorine. Whatever process or processes are
chosen to comply with the TTHM MCL does not detract from
the fact that the integrity of the biological quality of
the drinking water must not be compromised.
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LABORATORY CERTIFICATION CRITERIA FOR TRIHALOMETHANES
EPA Regional offices should use the following criteria
for certifying laboratories for total trihalomethane (TTHM)
analysis until the revised laboratory certification manual
becomes available. Most of the items below constitute
minimum recommended requirements. Laboratories should
be encouraged to exceed these minimum criteria.
I. PERSONNEL
No minimum recommended requirements.
Some optional requirements are specified in,"Manual for the
Interim Certification of Laboratories Involved in Analyzing
Public Drinking Water Supplies". In addition, if the laboratory
performs gas chromatography-mass spectrometry (GC-MS) analyses,
the following are recommended minimum qualifications for the
GC/MS operator.
1. Training: Satisfactory completion of a minimum one
week course in GC/MS offered by equipment manufacturer,
professional organization, university or other qualified
operator.
2. Experience: Minimum of one year experience in the
operation of a GC/MS instrument.
II. LABORATORY FACILITIES
Minimum Recommended Requirements:
1. The laboratory must maintain a proper source of reagent
water which contains less than 0.4 ug/1 of each trihalo-
methane compound.
It is recommended that the laboratory facilities be clean,
air conditioned and with adequate lighting at the bench
top. It is also recommended that 150 to 200 square feet/person
be available. The laboratory should contain at least 15
linear feet of usable bench space per analyst. The laboratory
should have provisions for the disposal of chemical wastes.
III. LABORATORY EQUIPMENT
Minimum Recommended Requirements:
1. Analytical balance: This should provide sensitivity
of at least 0.1 mg.
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2. Gas chromatograph: A commercial or custom-designed
gas chromatograph (GC) with a column oven capable
of operating to temperatures up to 200°C. Additional
recommended requirements are listed below by methodology,
2.1 TTHM purge and trap: The instrument must be
temperature programmable from 45° to 220° at
about 8° C/min and equipped with either a
microcoulometric titration or electrolytic
conductivity detector.
2.2 TTHM by liquid/liquid extraction: The instrument
must be equipped with a linearized (frequency
modulated) electron capture detector.
2.3 TTHM by gas chromatography/mass spectrometry:
The gas chromatograph, which must be temperature
programmable, should be interfaced to the mass
spectrometer with an all-glass enrichment device
and an all-glass transfer line. Mass spectral
data are to be obtained with electron-impact
ionization at a nominal electron energy of 70
eV. The mass spectrometer must produce a spectrum
that meets all criteria in Table 3 when 50 mg.
or less of p-bromofluorobenzene is introduced
into the gas chromatograph. An interfaced data
system is required to acquire, store, reduce
and output mass spectral data. The data system
must be equipped with software to acquire and
manipulate data for only a few ions that were
selected as characteristic of trihalomethanes
and the internal standard (or surrogate compound).
3. Purge and trap system: A commercial or custom-designed
system containing three separate elements.
3.1 Purging device: Must be designed for a 5 ml.
sample volume. Gas inlet must disperse finely
divided gas bubbles through the sample.
3.2 Trapping device: Must be capable of retaining
purged trihalomethanes at room temperatures.
3.3 Desorber assembly: Must be capable of heating
the trapping device to 180°C in one minute with
less than 40°C overshoot.
4. Drying oven: Temperature set at 105°C for drying
of cleaned sample bottles.
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TABLE 3. £-BROMOFLUOROBENZENE KEY IONS AND ION ABUNDANCE CRITERIA
Mass Ion Abundance Criteria
50 15 to 40% of mass 95
75 30 to 60% of mass 95
95 base peak, 100% relative abundance
96 5 to 9% of mass 95
173 less than 2% of mass 174
174 greater than 50% of mass 95
175 5 to 9% of mass 174
176 96 to 100% of mass 174
177 5 to 9% of mass 176
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5. Chlorine analysis: If a laboratory measures total
trihalomethane potential (MTP), it must have test
kits, apparatus or instruments capable of detecting
free residual chlorine.
IV. GENERAL LABORATORY PRACTICES
No minimum recommended requirements.
Some optional requirements are specified in "Manual for the
Interim Certification of Laboratories Involved in Analyzing
Public Drinking Water Supplies".
V. METHODOLOGY
Minimum Recommended Requirements:
The laboratory must use one of the methods specified below.
Purge and Trap GC - "The Analysis of Trihalomethanes in
Finished Waters by the Purge and Trap Method," Method 501.1,
EMSL, EPA, Cincinnati, Ohio 45268.
Solvent Extraction, GC - "The Analysis of Trihalomethanes
in Drinking Water by Liquid/Liquid Extraction," Method
501.2, EMSL, EPA, Cincinnati, Ohio 45268.
GC/MS - "Measurement of Trihalomethanes in Drinking Water
by Gas Chromatography/Mass Spectrometry and Selected Ion
Monitoring," Method 501.3, EMSL, EPA, Cincinnati, Ohio
45268.
All other methods are considered alternative analytical
techniques and procedures described under Section 141.27
of the NIPDWR are to be followed if a laboratory wishes
approval for their use.
VI. SAMPLE COLLECTING, HANDLING AND PRESERVATION
When the laboratory has been delegated responsibility for
sample collecting, handling and preservation, there must
be strict adherence to correct sampling procedures, complete
identification of the sample and prompt transfer of the
sample to the laboratory.
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Minimum Recommended Requirements:
1. The collector must be trained in sampling procedures.
2. Sampling locations: As specified in 40 CFR 141.30(b)
(1).
3. Sampling procedures: Follow procedures described
in Sections 6.4.5 and 6.4.6 of Appendix C, Part I,
40 CFR 141.
4. Sample bottles: Narrow mouth, 25 ml. or greater capacity,
screw cap, glass bottles are to be used. Bottle caps
should utilize TFE fluorocarbon face silicon septa
cap liners.
5. Sample stabilization: For the sample collection of
total trihalomethanes, sodium thiosulfate or sodium
sulfite must be added to each empty sample bottle
just prior to shipping to the sample site.
6. Maximum holding time: All samples must be analyzed
within 28 days after collection.
While laboratories should exercise discretion in all aspects of
sample collection and handling, where a laboratory has no
control over these factors, appropriate documentation should
be required from collector(s) to ascertain if minimum require-
ments are being met. For example, the laboratory can visually
check the samples to determine the use of appropriate containers,
the presence of air bubbles and proper labeling. If the minimum
criteria are not met, then the laboratory director should reject
the samples and so notify the authority requesting the analysis.
VII. QUALITY CONTROL
Minimum Recommended Requirements:
1. All quality control data must be available for inspection.
2. A copy of the analytical method used must be available
to the analyst(s).
3. A laboratory must demonstrate acceptable performance
on USEPA Performance Evaluation samples at least once
per year.
4. A laboratory should analyze known reference samples
(USEPA Quality Contol Sample or equivalent) once per
quarter. If errors greater than 20% occur, appropriate
corrective action must be taken and documented.
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5. For each day on which analyses are initiated, a laboratory
method blank must be analyzed with the same procedures
used to analyze samples.
6. The laboratory must analyze a known TTHM laboratory control
standard each day. If errors exceed 20 percent of the
true value, then all trihalomethane results since the
previous successful test are to be considered suspect.
7. A minimum of three calibration standards must be analyzed
each day to calibrate the gas chromatographic system.
If the laboratory can thereby demonstrate that the
instrument response is linear through the origin,
this requirement can be reduced to one standard within
the linear range of the instrument; providing the
response of the standard is within + 15 percent of
previous calibrations.
8. It is essential that the laboratory analyze a field
blank for trihalomethanes with each sample set. If
reportable levels for trihalomethanes are demonstrated
to have contaminated the field blank, then resampling
is essential.
9. The laboratory must analyze 10 percent of all samples
for TTHM in duplicate. A continuing record of all
calibration checks (accuracy) and duplicates (precision)
must be maintained.
10. Each time that the TTHM analytical system undergoes a
major modification or prolonged period of inactivity,
the precision of the system must be demonstrated by the
analysis of replicate laboratory standards.
11. It is critical that laboratories which analyze for TTHMs
by liquid-liquid extraction demonstrate that source waters
bei'ng analyzed do not contain interferences under the
chromatographic conditions selected.
12. If a mass spectrometer detector is used for TTHM analysis,
the mass spectrometer performance tests described
under equipment specifications using BFB must be conducted
once during each 8-hour work shift, and records of
satisfactory performance and corrective action must
be maintained.
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VIII. DATA HANDLING
Minimum Recommended Requirements:
1. If a laboratory is responsible for sample collection,
it must document the information required by 40 CFR
141.33 (1) and (2) and return this information to
a water supply with the results for each trihalomethane
sample. Information required by 40 CFR 141.33(3),
(4), and (5) must be transmitted with analytical results
along with the detection limits determined for the
appropriate set of trihalomethane analyses.
2. Records of chemical analyses must be kept by the laboratory
for not less than 3 years. This includes all raw
data, calculations and quality control data.
IX. MAXIMUM TOTAL TRIHALOMETHANE POTENTIAL
Laboratories that are engaged in the determination of maximum
total trihalomethane potential (MTP) must meet the following
requirements for that test.
1. Method: Gas chromatography. "Method for the Determination
of Maximum Total Trihalomethane Potential - Method
510.1." EMSL, EPA, Cincinnnati, Ohio 45268.
2. Sample container: TTHM sample bottle.
3. Supplemental equipment: Constant temperature storage
container, water bath or incubator, 25°C or above.
4. The laboratory must be certified for TTHM analysis.
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APPENDIX
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R-2A Media Preparation
Ingredient Concentration g/1
Yeast Extract 0.5
Proteose Peptone No. 3 0.5
Casamino Acids 0.5
Glucose 0.5
Soluble Starch 0.5
Sodium Pyruvate 0.3
K2HPO4 0.3
MgS04.7H2O 0.05
Agar 15.0
Dissolve all ingredients except for agar. Adjust pH to
7.2 with K2HP04 or KH2P04 before adding agar. Add agar.
Heat medium to boiling to dissolve agar and autoclave for
15 minutes at 121°C, 15 psi.
Note: For further information, see "Abstracts of the
Annual Meeting of the American Society for
Microbiology" (1979); Reasoner, Donald J.,
Entry N-7, Page 180.
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Water Supply Guidance # 72
All Maximum Contaminant Levels (MCLs) contained in the
National Interim Primary Drinking Water Regulations are
expressed in the number of significant digits permitted
by the precision and accuracy of the specified analytical
procedure(s). Data reported to the State or EPA should be
in a form containing the same number of significant digits
as the MCL. In calculating data for compliance purposes
it is necessary to round-off by dropping the digits that
are not significant. The last significant digit should be
increased by one unit if the digit dropped is 5,6,7, 8 or 9.
If the digit is 0, 1, 2, 3 or 4. do not alter the preceeding
number.
For example, if the monthly mean for coliform bacteria is
1.4999, the reported result should be 1 (one). A result
of 3.50 should be rounded to 4 (four).
Chemical and radiological data may be treated in like manner
Analytical results for mercury of 0.0016 would round-off
to 0.002 while 5.4 pCi/1 of combined radium-226 and radium-
228 would round down to 5 pCi/1.
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Public Notification Requirements
If a community water system fails to comply with an applicable
maximum contaminant level, fails to comply with an applicable
testing procedure or fails to perform any monitoring require-
ment, then the supplier of water shall report to the state within
48 hours and notify persons served by the system of the failure
within three months. Within ten (10) days of completion of
each required public notification, the supplier shall submit
to the state a representative copy of each type of notice
distributed, published or posted.
Determination of MCL compliance with THM is based on the
running annual average of quarterly samples collected by the
system. If the average of samples covering any twelve (12)
month period exceeds the MCL, then the supplier shall report to
the state within 48 hours and notify the public within three
months. For example: Assume that System A has the following
analytical results for the latest four (4) quarters - 0.123 mg/1 ;
0.095 mg/1; 0.122 mg/1; and 0.098 mg/1 respectively. The
running annual average = (0.123 + 0.095 + 0.122 + 0.098)/4 =
0.11 mg/1. System A is required to issue a public notice
because the annual average of the four quarters exceeds the
MCL, even though the fourth quarter's result is less than
0.10 mg/1. This computation of the running annual average
is performed quarterly as the new quarterly average is available.
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WATER SUPPLY GUIDANCE # 74
Background
For years, many public water systems have added chloramines
(chlorine plus ammonia) to drinking water as a primary or
secondary disinfectant. Also, when breakpoint chlorination
is not practiced, both inorganic and organic chloramines may
be present in finished drinking water. Because of concern
regarding the formation of trihalomethanes (THMs) from chlorine
and organic matter, and in some cases because of requirements
for compliance with drinking water regulations limiting THM
concentrations (40 CFR 141.30), a number of water supply
systems have switched, or are contemplating switching, from
chlorine to chloramine or chlorine dioxide as their primary
disinfectant. Any water supply which plans to change dis-
infectants should be made aware of the potential problems
created by such a change and should notify consumers,
particularly those most likely to be affected, in advance of
the change. Care should also be taken to avoid unnecessarily
high levels of combined residuals.
A potentially serious problem arises when tap water containing
chloramines is used in hemodialysis (artificial kidney machines).
Chloramines pass through the dialysis membrane and their toxicity
to patients under dialysis conditions is undisputed (Eaton, et
al. 1973). Chlorine dioxide and its by-products may have
similiar effects. Operators of dialysis centers know that
tap water must be treated before use in dialysis, but again
there have been a number of cases of illness reported due to
chloramine or some other chemical in tap water. The Association
for the Advancement of Medical Instrumentation has proposed a
limit of 0.1 mg/1 for chloramine in hemodialysis water. It is
imperative that dialysis centers and users of home dialysis
systems be informed that chloramines or chlorine dioxide are
to be used in the public water system and that treatment to
remove them is essential. Other substances in tap water besides
chloramines are also known to interfere with dialysis. These
include copper, fluoride, sulfate, nitrate, zinc and aluminum.
The types of controls available to users include carbon filtraton
and reverse osmosis or chemical reduction.
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The toxicity of chloramine to fish is well-known. Most breeders
and owners of tropical or other aquarium fish know that tap water
should not be used in aquaria without proper treatment and aging.
Yet, a number of cases of aquarium fish being killed by chloramine
in tap water have been reported, particularly when conversion
between disinfection methods has occurred at the treatment plant.
Since chloramine is more persistent than free chlorine (which is
also toxic to fish), treatment and aging of water to be used in
aquaria is more critical when chloramine is present. Suggested
action for fish fanciers, breeders or pet shop owners includes
the use of activated carbon filters. Care needs to be taken to
replace filter cartridges before breakthrough can occur.
References
Eaton,J.W., Koplin,C.F., Swofford,H.S., Kjellstrand,C.M. and
Jacob,H.S.,"Chlorinated Urban Water: A Cause of Dialysis-Induced
Hemolytic Anemia", Science 181:463-4, 1973.
Proposed Standard for Hemodialysis Systems, Association for the
Advancement of Medical Instrumentation. AAMI RD5-1981. June, 1981.
National Interim Primary Drinking Water Regulations: Control of
Trihalomethanes in Drinking Water. Federal Register, November 29,
1979, p. 68624.
Guidance
Section 141.30(f) directs systems which make any significant modifications
to existing treatment processes for the purposes of achieving compliance
with Section 141.12(c) to submit and obtain state approval of a detailed
plan setting forth proposed modifications. The Office of Drinking Water
recommends that utilities changing disinfectants notify the public of
the change and that this notification, the text and announcement
schedule be included in the plan. In particular the notification should
include hospitals, kidney dialysis facilities and fish breeders.
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References
1. National Interim Primary Drinking Water Regulations,
Control of Trihalomethanes in Drinking Water, Final
Rule; U.S. EPA, Federal Register, Vol. 44, No. 231.
November 29, 1979-
2. Symons, J.M., Stevens, A.A., Love, O.T. DeMarco,
J., Clark, R.M., Geldreich, E.E., Treatment Techniques
for Control of Trihalomethanes in Drinking Water.
EPA-600/2-81-156. U.S. EPA, Cincinnati, Ohio, 1981.
3. Vogt, C., Regli, S. "Controlling Trihalomethanes While
Attaining Disinfection." In: Proceedings of AWWA Seminar on
Water Disinfection with Ozone, Choramines, or Chlorine
Dioxide. Atlanta, Georgia, June 15, 1980.
4. The Disinfection of Drinking Water, National Academy
of Sciences, EPA 68-01-3169, U.S. EPA, Washington,
D.C., 1979.
5. Miller, G.C., Rice, R.G., Robson, C.M., Kuhn, W.,
and Wolf, H. An Assessment of Ozone and Chlorine
Dioxide Technologies for Treatment of Municipal Water
Supplies, EPA 600/2-78-147, U.S. EPA, Cincinnati, Ohio, 1978.
6. Symons, J.M., et al. Ozone, Chlorine Dioxide and Chloramines
as Alternatives to Chlorine for Disinfection of Drinking
Water - State-of-Art, ORD,U.S.EPA,Cincinnati,Ohio,
November, 1977.
7. Hoff, J.C., Geldreich, E.E., "Comparison of the Biocidal
Efficiency of Alternative Disinfectants." In: Proceedings
of AAWA Seminar on Water Disinfection with Ozone, Chloramines
or Chlorine Dioxide. Atlanta, Georgia, June 15, 1980.
8. Stevens, A.A. , Symons J.M. "Measurement of Trihalomethanes
and Precusor Concentration Changes Occuring During Water
Treatment and Distribution." Jour. AWWA 69:10:546,
October, 1977.
9. "Committee Report on Disinfection." Jour. AWWA 70:4:219,
April, 1978.
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10. Allen, M.J., Geldreich, E.E., "Evaluating the Microbial
Quality of Potable Waters", In: Evaluation of the
Microbiology Standards for Drinking Water. Ed. Hendricks,
C.W., EPA 570/9-78-OOC, U.S. EPA, Washington, B.C.,
September, 1978.
11. Geldreich, E.E., Allen, M.J., Taylor, R.H., "Interferences
to Coliform Detection in Potable Water Supplies". In:
Evaluation of the Microbiology Standards for Drinking
Water. Ed. Hendricks, C.W., EPA 570/9-78-OOC, U.S. EPA,
Washington, D.C., September, 1978.
12. Standard Methods for the Examination of Water and
Wastewater, 15th Edition, American Public Health Associ-
ation, American Water Works Association, Water Pollution
Control Federation. Washington, D.C.
13. Microbiological Methods for Monitoring the Environment,
EPA-600/8-78-017, Environmental Monitoring and Support
Laboratory, Office of Research and Development, U.S. EPA,
Cincinnati, Ohio, December, 1978.
14. Methods for Chemical Analysis of Water and Wastes,
EPA-600/4-79-020, Environmental Monitoring and Support
Laboratory, Office of Research and Development, U.S. EPA,
Cincinnati, Ohio, April, 1979.
15. Annual Book of ASTM Standards, Part 31 Water, American
Society for Testing Materials, Philadelphia, Pennsylvania.
16. Geldreich, E.E., "Maintaining Microbiological Quality", In:
Handbook of Treatment Techniques for the Control of
Trihalomethanes in Drinking Water. Symons, et al.,
EPA-600/2-81-156. U.S. EPA, Cincinnati, Ohio7T981.
17. Gulp, G.L., "Disinfection", in New Concepts in Water
Purification. Von Nostrand Reinhold Company, New York,
New York, 1974.
18. Personal communication with C. Johnson (University of
North Carolina), December, 1980.
19. Letter from G.C. White to Office of Drinking Water,
EPA, Washington, D.C., April, 1978.
20. Selna, M.W., Miele, R.P., "Disinfection for Water Reuse".
In: AWWA Disinfection Seminar Proceedings, Anaheim,
California, May 8, 1977.
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21. Personal communication with G.C. White, December, 1980-
22. Tuepker, J.L., "Practices and Experience in Disinfection
of Potable Water at St. Louis County Water Company",
In: Proceedings AWWA Disinfection Seminar, Anaheim,
California, May, 1977.
23. Harms, L.L., Looyenga, R.W., Preventing Haloform Formation
in Drinking Water, EPA 600/2-80-094, U.S. EPA, Cincinnati,
Ohio, August, 1980.
24. Brodtman, N.U., Koffsky, W.E. and DeMarco, J., "Studies
of the Use of Combined Chlorine (Monochloramine) as a
Primary Disinfectant of Drinking Water", Presented
at Third Annual Conference of Water Chlorination:
Environmental Impact and Health Effects; Colorado Springs,
Colorado, Nov. 2, 1979.
25. Snead, M.C., Oliveri, V.P-, Kruse, C.W., Kawata, K.,
Benefits of Maintaining A Chlorine Residual in Water
Supply Systems^EPA 600/2-80-010.U.S. EPA, Cincinnati,
Ohio, June, 1980.
26. Bull, R.J., "Health Effects of Alternate Disinfectants
and Their Reaction Products", JAWWA 72:5:299. May, 1980.
27. Rice, R.G., "The Use of Ozone to Control Trihalomenthanes
in Drinking Water Treatment", Presented at International
Ozone Association World Congress on Ozone Technology,
Houston, Texas, September, 1979.
28. Statement of Basis and Purpose for Amendments to the
National Interim Primary Drinking Water Regulations;
Criteria and Standards Division, Office of Drinking
Water, U.S. Environmental Protection Agency; June,
1980.
29. Technologies and Cost for the Removal of Trihalomethanes
from Drinking Water; Science and Technology Branch,
Criteria and Standards Division, Office of Drinking
Water, U.S. Environmental Protection Agency; February,
1982.
30. Proceedings of Symposium on, "Health Effects of Drinking
Water Disinfectants and Disinfectant By-Products",
Environmental Health Perspectives, December, 1982.
31. Wentsel, R.S., O'Neill, P.E. and Kitchens, J.F.,
"Evaluation of Coliphage Detection as a Rapid Indicator of
Water Quality", Applied and Environmental Microbiology, Vol
43, Page 430-434.
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
. REPORT NO.
1PA 570/9-83-002
2.
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
5. REPORT DATE
Trihalomethanes in Drinking Water -
Sampling, Analysis, Monitoring and
Compliance
6. PERFORMING ORGANIZATION CODE
. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Science & Technology Branch
Criteria & Standards Division
U.S. EPA
Washington, DC 20460
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency
Office of Drinking Water
401 M Street SW
Washington, D.C. 20460
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This document summarizes the issues involved in the
implementation of Federal regulations which limit the levels of
trihalomethanes in community water supplies. The underlying
objective of the regulations is to provide public drinking
water with fewer potential chemical health hazards while ensuring
continued protection agains pathogenic micro-organisms. This
document is purely advisory in nature and is meant to supplement
those regulations. The purposes of this document are to assist
EPA Regional Offices, individual States and affected systems in
their implementation of the trihalomethane regulations and to help
ensure that actions taken toward implementation will be consistent,
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COS AT I Field/Group
drinking water
trihalomethanes
community water systems
federal regulations
18. DISTRIBUTION STATEMENT
Ooen
19. SECURITY CLASS (Tins Report/
Non-Sensitive
21. NO. OF PAGES
20. SECURITY CLASS (This page)
22. PRICE
EPA Form 2220-1 (R«v. 4-77) PREVIOUS
EDITION IS OBSOLETE
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