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Assessment of
On-Site Graywater and
Combined Wastewater
Treatment and
Recycling Systems
•ATIOMAI. AISOCIATIM Of
UATIII6 COOUUGCMIKACTOKS
National Association of
Plumblng-Heatlng-Coollng Contractors
180 S. Washington Street
P.O. Box 6808
Falls Church, VA 22046
1 (800) 533-7694, Fax: (703) 237-7442
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ASSESSMENT OF ON-SITE
GRAYWATER AND COMBINED WASTEWATER
TREATMENT AND RECYCLING SYSTEMS
Submitted to:
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, DC 20460
August 3, 1992
Submitted by:
National Association of Plumbing-Heating-Cooling Contractors
180 S. Washington Street
P.O. Box 6808
Falls Church, VA 22046
and
Enviro-Management & Research, Inc.
5415-B Backlick Road
Springfield, VA 22151
1992, National Association of Plumbing-Heating-Cooling Contractors
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ACKNOWLEDGEMENTS
We acknowledge with deep gratitude the sponsorship of the U.S. Environmental
Protection Agency and the National Association of Plumbing-Heating-Cooling
Contractors Association, and the direction provided by Robert Bastian and Joanne
Oxley. We also express our appreciation for the extremely valuable information and
insights provided by Kenneth Krauska, John Irwin, Dr. Bahman Sheik, Allison
Whitney, Art Ludwig and Larry Farwell.
Special thanks also are due to Martin Karpiscak of Office of Arid Land Studies,
University of Arizona: Scott Chaplin of Rocky Mountain Institute: and the many
manufacturers, distributors and plumbing contractors for their generosity in sharing
information and data with us.
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TABLE OF CONTENTS
Page
SUMMARY AND CONCLUSIONS iv
I. INTRODUCTION
Objective {":
Research Methodology , /„
II. CHARACTERISTICS OF WASTEWATER TT-,
Household Wastewater Generation TT~,
Chemical Quality }}":
Biological Quality n"3
in. GRAYWATER RECYCLING SYSTEMS TTT.!
Graywater Uses In_1
Basic System Concepts jjj"2
Currently Available Technologies ffl-11
Current and Potential Applications m-11
Application Considerations m-14
Installation Considerations m-19
Operation and Maintenance Considerations in-19
Potential Impact of Graywater Use on the
Sewer System m-20
IV. COMBINED WASTEWATER TREATMENT AND
RECYCLING SYSTEMS w ,
Combined Wastewater Uses jy] 1
Basic System Concepts jY^j
Currently Available Technologies jy'o
Current and Potential Applications jV^
Application Considerations j^o
Installation Considerations jyI4
Operation and Maintenance Considerations IV_4
V. BARRIERS AND CONSTRAINTS y.j
Lack of Statutory Regulations y.j
Restrictive and Ambiguous Plumbing Codes V-1
Lack of a National Standard for On-Site
Recycled Water Quality v_4
Lack of Confidence in Standard Practice
for Controlling Cross Connections V-4
Preference for Reclaiming Water from Municipal
Wastewater Treatment Plant Rather Than On-Site
Wastewater Treatment and Recycling V-5
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VI. ECONOMICS OF ON-SFTE WASTEWATER TREATMENT AND RECYCLING
SYSTEMS
Economic Factors
Economics of On-Site Wastewater Treatment and
Recycling Systems Versus Reclaimed Water
Ffoma Central Plant
VII. GLOSSARY
VIE. REFERENCES
APPENDIX A:
APPENDIX B:
APPENDIX C:
Workplan for the Evaluation of the
Distribution of Graywater through
Subsurface Irrigation
Proposed Code Change to the Uniform
Plumbing Code
NAPHCC Graywater Survey
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SUMMARY AND CONCLUSIONS
America is facing a critical water supply shortage because of population and economic
growth, persistent drought conditions, and a lack of adequate planning for future
water needs. This isjevidenced by current efforts in many states, as well as semi-arid
and arid areas, to adopt stricter standards for water conservation. In addition an
increasing number of communities are imposing sewer moratoriums or sewer canacitv
restrictions. * y
Historically, public policy, and health codes have mandated centralized collection and
treatment of all wastewater. On-site wastewater treatment and recycling systems have
been allowed onty in very few instances. Some of these systems involve segregation of
individual waste sources into dual piping systems - graywater and blackwater
Gray water generally is denned as used water generated by clothes washing machines
showers, bathtubs, and sinks. Blackwater is water that is flushed down toilets and
urinals.
Many states and counties currently are reexamining their policies and codes regarding
on-site wastewater treatment and recycling due to a variety of factors: persistent
drought and water shortages, lack of adequate wastewater treatment and disposal
facilities, and growing emphasis on demand-side management strategies. Finding
additional water supplies and expanding existing wastewater treatment plant capacity
is expensive, sometimes impractical and. at best, involves long range planning.
Fortunately, solutions are available which can reduce water consumption and peak
demand in an environmentally acceptable manner. A number of devices can help
water users reduce consumption and demand without any appreciable impact on
lifestyles. Typical of these are low-flow toilets, low-flow shower heads, and faucet flow
restrictors. Generally speaking, these have been well received and have become
steadily more popular as the cost of municipal water has risen.
Further reductions can be achieved through the use of on-site wastewater treatment
and recycling systems that permit reuse of graywater or combined wastewater for
landscape irrigation and toilet and urinal flushing. As an example, in the typical
household, approximately 34 percent of the water consumed is used in flushing of
toilets. The remaining 66 percent of the water for the most part is available for on-site
recovery and reuse. On-site wastewater treatment and recycling systems can be used
in all types of residential and commercial buildings and in most types of institutional
and industrial buildings.
To develop a better understanding of on-site wastewater treatment and recycling
technology (including associated costs), regulatory and institutional constraints, and
health and safety issues, information was obtained from a variety of sources,
including the members of National Association of Plumbing-Heating-Cooling'
Contractors (NAPHCC). manufacturers, suppliers, and various state and local
government agencies.
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FINDINGS
Graywater recycling systems currently are being used primarily for sub-surface
landscape irrigation (employing the mini-leachneld design) or toilet flushing. They
currently are available from less than 20 manufacturers or suppliers. They range from
simple systems for residential applications to complex fully automated systems for
commercial and industrial applications.
Regardless of their complexity, all graywater systems consist of most or all of the
following major elements.
Storage tank(s) (typically made of fiberglass or industrial-strength plastic)
Piping (color-coded PVC)
Filters (polyester, cloth, etc.)
Pump (fractional horsepower)
Valves (three-way and check)
Controls (manual or automatic)
When properly installed, operated, and maintained, graywater systems can "recycle"
some of the less contaminated household water that usually flows into a sewage or
septic system for treatment. This is accomplished through use of various methods and
techniques for collection, treatment and disinfection.
The collection system employs dual wastewater piping ~ one for graywater and one for
blackwater. While the graywater from bathroom sinks, showers, bathtubs, clothes
washing machines and laundry sinks Is directed to the storage tank, the blackwater
piping remains plumbed to the sewer line or septic tank disposal system.
The treatment methods employed depend upon the application Involved. They include
media filtration, collection and settling, biological treatment reverse osmosis,
sedimentation/filtration, and other physical treatment The most common treatment
method currently employed involves the use of media nitration.
Four different disinfection techniques are typically used to treat graywater, as well as
combined wastewater, for reuse within or outside a building. These techniques involve
the use of ultraviolet irradiation, ozone, chlorine, and iodine crystals.
Combined wastewater treatment and recycling systems are different from graywater
recycling systems in that they collect and treat the total wastewater (graywater and
blackwater) for reuse and/or disposal. Of the less than 100 on-site combined
wastewater treatment and recycling systems in use, most recycle combined
wastewater for toilet and urinal flushing.
Combined wastewater treatment and recycling systems utilize more complex methods,
techniques and controls than graywater systems for wastewater collection and
treatment Many systems use combination treatment methods such as batch
processing using aerobic treatment collection, settling, and sand filtration, or biological
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treatment with filtration and disinfection. The disinfection methods typically employed
include ultraviolet irradiation or ozone.
Several studies have been performed in the past to document the chemical
characteristics of household graywater and combined wastewater. Results indicate
that the chemical characteristics of household graywater are as follows- biochemical
oxygen demand (BOD) (51% to 80% of combined sewage); phosphorus (58% to 86% of
combined sewage): nitrogen (1-33% of combined sewage); and total suspended solids
(23-64% of combined sewage). The pH of graywater varies from 5.7 to 7.8. In contrast
little research has been performed to document the bacteriologic characteristics of
household graywater or combined wastewater. The limited studies that been
performed have produced very diverse data.
On-site graywater and combined wastewater treatment and recycling systems are soil
not permitted by numerous states and localities. In fact, many states and localities do
not even recognize water conservation and on-site water recycling activities. Currently,
only 10 states have policies, recommendations, or regulations permitting the use of
on-site graywater recycling systems, and only 8 states permit the use of on-site
combined wastewater treatment and recycling systems as shown in Table 1. None of
the states permit surface discharge of graywater or treated wastewater. unless
discharge standards are met.
Several barriers and constraints currently prevent the widespread acceptance and use
of on-site wastewater treatment and recycling systems. These include: lack of
statutory regulations; restrictive and ambiguous plumbing codes; lack of standards for
on-site recycled water, lack of confidence in standard practice for controlling cross
connection: and preference for use of reclaimed wastewater from a central municipal
wastewater treatment plant rather than from an on-stie wastewater treatment and
recycling system.
The initial cost of a graywater recycling system installed in a single-family residential
or small commercial application typically ranges from $500, for a basic "no-frills"
system, to $5,000, for a fully automated system: the cost of a combined wastewater
treatment and recycling system for the same applications rainges from $4,500 to
$8,500. Initial cost for combined wastewater treatment and recycling systems in larger
commercial and industrial facilities typically are approximately $1.00 per gross square
foot. This includes the cost of equipment and installation of components. It also
includes the cost of standby sewer connection required by some systems to emergency
service and periodic residual solids disposal. Costs not included are building space for
equipment and return water plumbing.
Operating costs are related principally to energy and demand. Energy is consumed in
on-site graywater and combined wastewater treatment and recycling systems by
electric motors that operate pumps and aeration equipment and by disinfection
equipment (e.g., ultraviolet lamps). These costs vary widely depending upon the
system being considered and. thus, are difficult to document. One manufacturer
(Thetford Systems. Inc.) did provide estimates of annual energy consumption for its
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Table 1: States with Policies and Regulations on Graywater and
Combined Wastewater Treatment and Recycling Systems
States
Graywater
Combined
Wutewater
Systems
Contact
Alabama
Alaska
Arizona
Arkansas
California
Colorado
Connecticut
Delaware
Florida
Georgia
Hawaii
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Nebraska
Nevada
New Hampshire
New Jersey
New Mexico
New York
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington
West Virginia
Wisconsin
Wyoming
George Holcombe (305) 242-5007
Dick Famell (907) 465-2656
Robert Wilson (602) 257-2270
Patrick Harris (501) 661-2171
DaveQuinton (916)445-1248
Phil Hegeman (303) 331-4564
Arthur Castellawo (203) 566-1759
Ron Graeber (302) 736-4762
David York (904) 488-4525
Bill McGiboney (404) 894-6644
Felix Udasco (808) 543-8288
Rick Maltory (208) 334-5845
Dave Antonaccia (217) 782-4977
Allen Dunn (317) 633-0100
Darryi McAllister (515) 281-6682
Steve Page (913) 296-1343
Dave Nichols (502) 564-4856
George Robichaux (504) 568-5100
Ken Meyer (207) 289-5684
Jay Prager (410) 631-3652
Christos Dimisioris (617) 292-5912
Tom Hoogerhyde (517) 335-9214
Dave Morisette (612) 623-5517
Ralph Turhbow (601) 960-7696
Nix Anderson (314) 751-6090
Rick Duncan (406) 444-2544
Terry Philippi (402) 471-2541
Dale Ryan (702) 686-4750
Barry Lehneman (603) 271-3505
Bob Berg (609) 984-1429
Bob Kirkpatrick (505) 841-9450
Ralph Stewart (518) 661-2171
Tim Woody (919) 733-2895
Dave Bergsagel (701) 221-5210
Tom Grigsby (614) 466-1450
Dan Hodges (405) 271-7362
Sherman Olson (503) 229-6443
Milt Lauch (717) 787-8184
Mark Boucher (401) 227-2306
Leonard Gordon (803) 734-5096
Bill Baer (605) 773-3296
Steve Morse (615) 741-0690
Sherman Hart (512) 458-7375
Don Hanson (801) 538-6159
Ernie Christiansen (802) 879-6563
Alan Knapp (804) 786-1750
Don Alexander (804) 786-1750
Ron Forren (304) 348-2971
Dave Russell (608) 266-0056
John Harrison (307) 777-7431
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graywater systems for applications in hotels, motels, and recreational facilities These
range from 13.000 kWh (for 350 gpd system) to 95.000 kWh (for 8.500 gpd system).
Maintenance costs typically include the cost ofreplacement parts, replacement labor
filter cleaning labor.-equipment repair, and cost of maintaining control systems. For '
residential anrf'small commercial applications, the annual maintenance cost
associated with graywater systems is about $50 to $100. Including the cost of filter
replacement and labor for periodic maintenance and Hushing of the system. For
combined wastewater treatment and recycling systems in large commercial'and
industrial applications, the annual maintenance costs can range up to 15 percent of
initial equipment cost or approximately $0.15 per gross square foot.
CONCLUSIONS
Based on the research findings, the following conclusions can be reached.
1. On-site wastewater treatment and recycling systems! are a potentially important
demand-side management option that can result in significant metered potable
water savings (up to 50% reduction and about 75-90% in commercial
buildings). Their use also can reduce peak demand on central municipal
wastewater treatment plants.
2. Current applications of on-site wastewater treatment and recycling systems
generally are being driven by factors such as persistent drought conditions,
lack of available sanitary sewers, overloaded central sewage treatment plants,
poor site or soil conditions, and water conservation.
3. The initial cost of all on-site wastewater treatment and recycling technologies
remains high. This is because the current market remains restricted to those
states that face persistent drought conditions, and to those areas where sewer
systems are not available or soil conditions do not permit use of conventional
septic tank/leach field systems. The lack of national standards, guidelines,
and\or regulations is another impediment.
4. Each state and county currently must establish its own standard and develop
its own regulations with regards to the use of on-site graywater recycling and
combined wastewater treatment and recycling systems. This regulatory process
is generally slow and, thus, the market for on-site wastewater treatment and
recycling systems remains too small and fragmented.
5. Although there is a growing acceptance that wastewater recycling is an
important strategy for water conservation and peak reduction, public health
and building officials in many states prefer the use of reclaimed water from
central municipal plants rather than the use of recycled water from on-site
wastewater treatment and recycling systems. Reclaimed water is preferred
because it has superior water quality and offers lower health risks. In addition,
centralized operation permits better control over the operation and
viii
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maintenance of the system. Also, reclaimed water from central municipal plants
is a major revenue source for the localities that employ it. This mind set of
public health and building officials continues to limit the widespread use of on-
site wastewater treatment and recycling systems.
6. Health and"safety risks associated with use of on-site graywater and treated
blackwater still are relatively unknown. Further study of the risk involved with
various end-uses is required.
7. Although most model or state plumbing codes currently do not address the use
of on-site graywater systems or combined wastewater treatment and recycling
systems, they do not prohibit use of these systems. An exception to this is the
state of California where six counties - Santa Barbara. San Luis Obispo.
Mariposa. Los Angeles, San Bernardino, and San Diego ~ have modified their
plumbing codes. As a result, code approvals are generally made on a case-by
case basis. Note, legislation (Assembly Bill No. 3518) recently has been passed
legalizing the use of on-site graywater systems in residential buildings on a
statewide basis. The Department of Water Resources has tillJuly 1, 1993 to
develop and adopt installation standards for on-site graywater systems.
RECOMMENDATIONS
It is evident that additional research is required. This research should include:
1. Develop guidelines for design and installation of graywater and combined
wastewater treatment and recycling technologies. The guidelines should
address, at a minimum, the following subjects.
Filtration processes for solids separation
Chlorination and other disinfection processes
Chemical treatment
Biological treatment
Use of defoaming agents for recharging of water
Pipe sizing and materials selection
Pipe identification
Cross connection controls
Pump sizing and design
Corrosion control
Effluent discharge facilities
2. Develop guidelines for operation and maintenance for alternative wastewater
treatment and recycling systems for use by appropriate facility personnel. The
guidelines should cover the following subjects.
• Control systems
• System operation
• Maintenance frequency and methods
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• Annual maintenance and parts Inventory
• Contracted services (e.g.. residual solids removal and wastewater
management services)
3. Demonstrate the validity of recommended systems, guidelines, and practices
through on-slte testing at representative sites. These sites should differ in
terms of location, type of system involved and type of application (residential
commercial, and industrial). Each site should be monitored for a period of one
year in order to determine if concepts, procedures, and recommendations
suggested are practical and cost-effective. Other information that should be
evaluated includes the following subjects.
Appropriateness and comprehensiveness of design guidelines
Inadequacy of design documentation (drawings and specification)
Problems encountered during installation
Corrective measures undertaken
Reliability of system operation
Adequacy of recommendations for maintenance
4. Develop and Implement stringent controls and standards for graywater
recycling systems. These controls and standards should include the following
subjects.
Set back requirements
Construction requirements
Minimum percolation rates and soil absorption characteristics
Minimum specifications pertaining to construction materials
Cross-connection control requirements
5. Develop a model regulatory program. This should include the following
elements.
Pennitting of uses
Licensing of graywater system on a local basis
Installation inspection and plan checking
Program funding through permit or user fees
Enforcement sanctions for violations of standards
6. Develop a modified model plumbing code which incorporates provisions for the
installation and use of on-site graywater and combined wastewater treatment
and recycling systems.
7. Develop end-user education materials. These materials should address the
following subjects.
.• Health, risks
• Operation and maintenance requirements
• Economics
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I. INTRODUCTION
Although fresh water is one of America's most precious resources, many Americans
consume far more water than they really need while drought conditions persist in
many areas of the-LLS. Compounding this problem, many of the aging sewage and
water treatment systems in the United States are incapable of meeting the demands
placed upon them due to increasing population and economic growth. In many urban
areas, water and wastewater treatment plants are overloaded and plagued by
operational problems due to years of neglect and deferred maintenance.
Finding additional water supplies and expanding existing wastewater treatment plant
capacity is expensive, sometimes impractical, and involves long-range planning.
Fortunately, America is beginning to recognize the limits of its natural resources and
the need to act in a more environmentally responsible manner to protect them.
Accordingly, the time has come to do more than simply attempt to keep up with
traditional water usage patterns. If significant change in water use patterns is to be
effected, it will be essential to modify the behavior of people-who consume water. As
significant a task as this may seem, .it already has been undertaken in other areas —
as when the electrical industry Initiated a demand-side management concept.
Through this approach, electrical, utilities around the nation developed a variety of
incentives which encouraged consumers to reduce their unnecessary use of electricity.
These conservation programs are working very well; as a result, numerous electrical
utilities have been able to defer construction of new generating facilities for decades.
A number of devices now are available to help water users conserve by reducing
consumption and demand without any appreciable impact on lifestyles. Typical of
these devices are low-flow toilets, low-flow shower heads, and faucet flow restrictors.
Generally speaking, these have been well received and have become steadily more
popular as the cost of municipal water has risen.
A significantly overlooked area of water conservation, however, has been the potential
for reuse of water on-site. As an example, in the typical household, approximately 34
percent of the water consumed is used in flushing of toilets. The remaining 66 percent
of the water, except that used in the kitchen, can be recovered for reuse by on-site
wastewater treatment and recycling systems for purposes such as landscape irrigation
and flushing of toilets and urinals.
On-site wastewater treatment and recycling systems potentially can be used In all
types of residential, commercial, institutional, and industrial buildings. However, their
application in these buildings has been limited to date due to a variety of factors,
including: restrictive regulations and plumbing codes; lack of standards for recycled
water quality; and perceived health and safety risks and impacts.
OBJECTIVE
The overall objective of this project was to assess graywater and combined wastewater
treatment and recycling technology currently available for residential, commercial.
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institutional, and industrial applications. Specific project objectives were to:
• Determine cost-effectiveness of available technologies.
• Evaluate regulatory and institutional (e.g., codes and standards) constraints
that hinder the widespread adoption of graywater and combined wastewater
treatmenTanS recycling technologies.
• Evaluate health and safety issues related to implementation of available
technologies.
RESEARCH MEETHODOLOGY
Information for this project was gathered through literature searches and contacts
with various associations, federal and state agencies, manufacturers, and research
institutes. A survey of state requirements was undertaken in order to develop
information on state regulations and applicable plumbing codes relative to graywater
and combined wastewater treatment and recycling systems. Furthermore, all
information collected was reviewed and analyzed to assure its comprehensiveness and
accuracy.
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II. CHARACTERISTICS OF WASTEWATER
Historically, public policy, and health codes have encouraged, if not mandated,
centralized collection and treatment of all household wastewater in urban areas
whenever possible. .Segregation of individual waste sources into graywater and
blackwater streams generally has not been permitted by local building officials and
health departments. However, this situation is changing, particularly in California
where several counties and cities now allow the use of graywater.
Graywater is used household water generated by clothes washing machines, showers.
bathtubs, and bathroom sinks. It usually does not contain water used in the kitchen.
The amount of oil, fat. and grease from dishwashing makes kitchen water smelly and
difficult to filter, likely to clog distribution pipes, and even more likely to attract pests.
However, an important exception to this general rule would be a double kitchen sink
with two separate drain pipes. One side can be hooked up to the sewer or septic tank
to receive all the greasy, oily, or cleanser-laden wastes, while the other side can be
connected directly to the graywater system and only receive dish-washing rinse water
and water used to clean vegetables.
Blackwater is water that is flushed down toilets and urinals. This water cannot be
directly reused. It must be: disposed to a sanitary sewer for treatment and disposal by
a central treatment plant: treated and disposed of on-site (e.g., by a septic tank and
leach field); or treated and recycled by an on-site wastewater and recycling system.
Due to the drought and water shortages in many parts of the country, and lack of
adequate wastewater treatment and disposal facilities, public policy and health codes
regarding graywater are being reexamine. Although graywater is difficult to
characterize because the number of household appliances and occupant use practices
vary greatly, several studies have been conducted in the past to study the
characteristics of typical household wastewater as well as how various pollutants are
distributed between the graywater and blackwater waste streams. A brief discussions
of finding Is as follows.
HOUSEHOLD WASTEWATER GENERATION
Table 2-1 presents data on the volumes of household wastewater typically generated
and average pollutant concentrations as reported by various investigations.
CHEMICAL QUALITY
The chemical parameters of concern in wastewater traditionally have included
biochemical oxygen demand (BOD. suspended solids, nitrogen, and phosphorous. For
reuse in irrigation, total dissolved salts and "trace" chemicals such as boron also are
important
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BOD of graywater varies greatly (from 51% to 80% of combined household sewage or
about 75 - 400 mg/1) as shown in Table 2-2. Kitchen sink water provides the heaviest
BOD loading of all graywater fixtures (40% to 70% depending on laundry use) as
shown in Table 2-3. The BOD loading, however, is much more soluble than combined
sewage. There is no toilet paper and no feces. As a result, the graywater BOD should
be more easily Elbdegraded than BOD in combined sewage.
Between 58% and 86% of the phosphorus in combined sewage is found in graywater,
most originating from laundry water. Note, the phosphorus content of graywater
depends upon the formulation and composition of the detergents used, e.g., low
phosphate detergents produce less phosphorus in laundry water. Nitrogen comes
predominately from urine and feces (67% to 99%). Most of the nitrogen in graywater
comes from the laundry.
The.amount of suspended solids is an important consideration when reuse involves
hose nozzles or any other restrictions in the water delivery line. Graywater contains
about 39% of the total suspended solids of combined sewage.
A continuing study by Karpiscak et al. (8) conducted Casa del Agua in Tuscon.
Arizona has shown that pH of graywater varies from 5.7 to 7.8 with a mean of 7.1.
Additional parameters being studied include, but are not limited to: phosphate,
sulfates. ammonia, BOD. turbidity, alkalinity, and chlorides.
Depending on the home, graywater accounts for 53% to 81% of all water used in a
typical, residential home as shown in Table 2-2. Siegrist (7) estimates average of 65%
of household wastewater is graywater. It equals roughly to 29.4 gallons per capita per
day. An estimate of the proportion of graywater in a suburban home is shown in
Figure 2-1.
In some rural (versus suburban) situations, the proportion of graywater volumes may
be much less. When water is gravity-fed, hand-pump, or hand-carried, water
conservation practices often are followed, and a per capita flow of 10 gallons of
graywater each day can be expected.
BIOLOGICAL QUALITY
In addition to the chemical/physical contributions shown in Tables 2-1 and 2-2.
bacteriological characteristics also are of interest. Since very little research has been
performed on raw individual household wastewater, the bacteriological content
determined in household septic tank effluent are presented in Table 2-4. Although the
values presented are for septic tank effluents, rather than raw wastewater, they do
give an idea of the bacteriological character of typical individual household
wastewater. As shown in Table 2-4, effluents from septic tanks receiving combined
household wastewater were found to consistently contain significant concentrations of
indicator bacteria and pseudomonas aeruginosa. Staphylococcus aureus and
salmonellae also were isolated, but only infrequently and in much lower
concentrations (Table 2-5).
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Table 2-3: Mean Waste water Characteristics (mg/l)
BODs
TOC
TS
TVS
TSS
TVSS
TOT-N
NH3-N
NO3-N
TOT-P
PO-P2
Flow
Gallons
Garbage
Disposal
1030
690
2430
2270
1470
1270
60
0.9 .
0
12
8
3.8
Kitchen
Sink
1460
880
2410
1710
720
670
74
6
0.3
74
31
4.8
Automatic
Dishwasher
1040
600
1EJOO
870
440
370
40
4.5
0.3
68
32
12.0
Clothes
Washer
270
200
880
350
200
120
13.5
0.6
0.5
39
10
15.1
Bath/
Shower
170
100
250
190
120
85
17
2
0.4
2
1
13.0
Composite1
609
1135
376
719
389
316
30.5
2.5
0.36
37.6
14.9
48.7
Computed as a flow weighted value.
2The composition of graywater is dependent upon the formulation and composition of detergents used
Source: Reference #9
II-5
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Kitchen
12.0%
Toilet
34.1%
Bathroom
24.5%
Misc.
6.2%
Laundry
23.2%
Figure 2-1: Proportions of Graywater in a Typical Suburban Home
Intuitively, one might expect that the majority of these organisms in combined
household wastewater exist in toilet wastes, with only low levels in the graywater. To
evaluate this hypothesis concerning graywater, Seigrist (10) conducted field studies at
the University of Wisconsin. In-house samples of the wastewater produced by two
sources, bathing and clothes washing, were obtained from each of six households in
the experiment over a two-week period. Bacteriological analyses were performed for
total and fecal coliforms and fecal streptococci The summarized results of the study
are presented in Table 2-6. As shown, the results demonstrate that a wide range of
indicator organisms can be expected in the raw bath and laundry wastewaters, which
in turn indicates a. potential for pathogen contamination.
n-6
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Table 2-6: Selected Bacteriological Characteristics of Bath and Laundry Wastewaters (Seigrist)1
Event
Clothes Washing3
Bathing
Organism
Total Conforms
Fecal Colifonns
Fecal Streptococci
Total Colifonns
Fecal Colifonns
Fecal Streptococci
Samples
41
41
41
32
32
32
Mean3
#/lOOml
215
107
77
1810
1210
326
'The results shown are based on in-house event sampling at each of six households.
2Log-normalized.
3Samples were obtained from the middle of the wash cycle. Samples taken from
several rinse cycles also were consistently lower than the corresponding wash cycle
values.
Source: Reference #7
To gain a better understanding of the actual magnitude of this "potential," Seigrist (6)
also evaluated several of the samples for two common pathogens, pseudomonas
aeruginosa and staphylococcus aureus. He found a very low incidence of
pseudomonas aeruginosa and very low concentrations (below 20/100 ml) when
present. Staphylococcus aureus was not found. A comparison of selected
bacteriological characteristics in various household wastewater streams is shown in
Table 2-7. Based on these findings, Seigrist (7) concludes "...the low pathogenic
contamination of these [laundry and bath] waters would seem to indicate a low
potential pathogenic contamination in graywater as a whole. Thus, while the raw
graywater is not innocuous, its potential contamination appears to be substantially
lower than that of either the toilet wastes or combined household wastewater."
There have been other studies that have examined bacteriological characteristics of
graywater as well. These landings are very different from that reported above. They are
summarized in Table 2-8.
Brandes (11) found fecal colifonn bacteria concentrations in graywater samples in the
same range of magnitude as usually observed in septic tank effluent generated from
all domestic sources. Boyle et al (12) reported that residential graywater contained
substantial amounts of pollutants, including fecal coliform bacteria, BOD5, suspended
solids, nitrogen, and phosphorus. The State of California Department of Health
Services (13) reported that the average bacteria concentrations were roughly
8,000,000 most probable number (MEN) total coliform organisms/100 milliliters (ml)
and 400,000 MPN fecal colifonn organisms/100 ml in water from the bathtub or
II-9
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Table 2-7: Comparison of Selected Bacteriological Characteristics in
Various Household Wastewater Streams (#/100 mis)
Organism
Total Conforms
Fecal Conforms
Fecal Streptococci
Pseudomonas Aeruginosa
Staphylococcus Aureus
Combined
Septic Tank
Effluent1
3.400,000
420,000
3.800
8.600
10-1000
Black
Water3
6,300.000
5,000.000
-
-
-
Graywater3
1810
1210
326
0-20
0
lMean values
2Based on the values determined by Olsson etal. (1) as diluted in four toilet flushes of
five gallons each.
3Based on the highest mean value determined in the bath and clothes washing
sampling. Tables 2-5 and 2-6.
Source: Reference #7
Table 2-8: Bacteriological Characteristics of Graywater
Total Colifonn/
100ml
Fecal Colifonn/
100ml
Brandes (11)
60.000-
134,000.000
5,000-21.000.000
Boyle et al. (12)
7,943.282
1,905.461
Calif. D.H.S. (13)
8.000,000*
3.000-
50,000.000B
400.000*
2.000-
10.000.0008
'^Samples from bathtub or shower
BSamples from washing machines
Source: Reference #14
shower, and 3.000 to 50.000.000 MPN total coliform organisms/100 ml and 2,000 to
10,000,000 MPN fecal coliform organisms/100 ml in water from washing machines.
Rose et al. (15) observed reductions of up to 99.9% in standard plate count, total
coliform, and fecal coliform concentration of 7.08 x 108, 3.89 x. 107. and 1.07 x 106,
respectively, in graywater after passage through aquacells planted with water
hyacinths, sand filtration, and storage.
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It is obvious from these limited studies that data on bacteriological characteristics is
quite variable. More study of health risks (dose, organisms, comparative risks, etc.)
from actual use of graywater is needed. The City of Los Angeles currently is
performing a comprehensive study of graywater systems. The primary objective of the
study is to obtain reliable quantitative data from actual use of graywater systems for
irrigation at eight residential sites located in the City of Los Angeles.
Because monitoring, testing, sampling, and analysis are the key to the success of the
Los Angeles project, guidelines for appropriate parameters of observation at the
optimum sampling frequency, along with controls to allow for statistical analysis and
comparison of the data, have been predetermined. At every site, composite soil and
stored water samples are being obtained for analysis at a laboratory under contract
with the Department of Water and Power (DWP). Additional control samples are being
obtained at half of the sampling events from areas not irrigated with graywater. Prior
to start of graywater irrigation, samples of soils have been obtained to establish
baseline conditions.
Anytime standing water is observed at irrigation sites, whether in dry weather or after
a rainfall, water, and soil samples are being conducted on a monthly basis, with
specific days of the month assigned to specific sites. Each sample is labeled
immediately after collection. Labels are attached, prior to sample collection in a
prescribed manner to prevent removal, confusion, or inadvertent switching. Samples
are immediately refrigerated at 4°C and transported to a certified laboratory for
analysis.
All samples are being analyzed for the following biological and chemical parameters.
within 24 hours after sample collection:
• Biological Parameters
Total colifonn
Fecal coliform
Enterococci
Salmonellae
Shigellae
• Chemical Parameters
pH
Total dissolved solids
Sodium
Calcium
Magnesium
Chloride
-f
At monthly intervals - but not necessarily coincidental with sampling - visual
observation notes are being taken at every site, supplemented with photography. The
following information is being recorded.
• Condition of connections, valves, fittings, appliances
• Condition of storage tank, if applicable
n-n
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Condition of filter, if applicable
Condition of irrigation system (clogging, slime, rupture, etc.)
Evidence of water on the soil surface
Evidence of runoff (including nature and extent)
Complaints, if any
Estimate~of volume of water saved in the preceding month
Adequacy of operation and maintenance
Evidence of excessive storage time in the storage tank
Evidence of mosquitoes in storage tank, application areas
Meter readings, including water meter and graywater meter
Although the study will not be completed until the end of 1992, the Office of Water
Reclamation has developed and issued a report (17) summarizing findings,
conclusions, and recommendations based on data collected during the first six
months. The report concludes that use of graywater at pilot sites, even with surface
application, does not pose a significant risk to the users or the community. It lists
certain generalizations in support of this conclusion.
• Indicator bacteria in the soil generally do not seem to increase with gravwater
application.
• Disease organisms, normally capable of surviving in the soil for a few days, are
not present in graywater irrigated areas. Neither have these organisms been
detected In the graywater sampled form storage tanks.
* Individuals assigned the task of cleaning graywater filters have not reported
any adverse effects.
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ill. GRAYWATER RECYCLING SYSTEMS
Traditionally, on-site septic tank/leach fields and centralized municipal sewage
treatment facilities have been the primary source of water disposal for single-and
multi-family residential buildings and complexes. But, as long-term water shortages
increase, and water conservation becomes more of a national issue, various on-site
water treatment and recycling technologies are being more actively explored. One
possible source that is receiving much public attention is graywater recycling.
This section presents a comprehensive overview of graywater. including: graywater
uses; basic system concepts; currently available technologies; current and potential
applications; application considerations; installation considerations; operation and
maintenance considerations; and potential impact of graywater use on the sewer
system
GRAYWATER USES
Graywater is being used in many areas of the U.S. Although it is being used primarily
for landscape irrigation and for toilet and urinaljlushing, it can be used for other
purposes as well. A brief description of these end-uses follows.
Landscape Irrigation
A significant amount of water is used in a typical home for landscape irrigation. In
some areas of the U.S.. particularly in semi-arid and arid areas of the Southwest it
can account for 50 percent of total household water use. Because an average of 20 to
40 gallons of graywater per person per day are produced in a typical home, graywater
could meet most, if not all, of the irrigation water needs of the trees, shrubs, and lawn
for many homes.
When graywater is used for landscape irrigation, it is further purified by the biological
activity in the topsoiL Soil microorganisms break down organic matter while plants
take up nutrients.
Toilet and Urinal Flushing
Treated graywater can be used as flush water for toilets and urinals. It's use in
residential applications of this type, however, has been limited.
Other Uses
Graywater also can be used as supply water for ornamental ponds and make-up water
for cooling towers used in many central air-conditioning systems.
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BASIC SYSTEM CONCEPTS
Graywater systems range from simple systems for residential applications (Figure 3-1)
to complex, fully automated systems for commercial and industrial applications
Regardless of their complexity, all graywater systems include most or all of the '
following majofelements.
Storage tank(s) (typically made of fiberglass or industrial-strength plastic)
Piping (color-coded FVC)
* Filters (polyester, cloth, etc.)
• Pump (fractional horsepower)
• Valves (three-way and check)
• Controls (manual or automatic)
Vent shall be within
trap arm distance of
running nap
Screened vents
3/32" or less
Graywater
source
IAT/FT
Union or equal (TYP)
Backwater Valve
with unions
Shut-off valve
Locking Cover (access)
VTR or 10' above grade
(support required)
Vented running trap.
if required
Approved water tight tank
Grade
IrrigaudnlSystem
Wye & 1/8 Bend
" Concrete Pad if
tank above ground
Backwater Valve
1/4-/FT
To building drain or sewer,
up-stream of sepoc tank, if any
Sewage Ejector
with Probes
To Irrigation system
Minimum of three irrigation
lines required for each system.
Abbreviations
C/O Cleanout
N.C. Normally Closed
VTR Vent Thru Roof
Figure 3-1: Graywater System for Landscape irrigation
Source: Reference #18
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When properly installed, operated, and maintained, graywater systems can'"recycle"
much of the household water that otherwise would flow into a sanitary sewer or septic
system for treatment. This is accomplished through use of various methods and
techniques for collection, treatment, disinfection, and irrigation. A brief description of
these methods and techniques follows.
Collection Methods
A graywater recycling system requires the use of a dual wastewater piping system in a
building -- one for graywater and one for blackwater. Separate graywater piping is
needed to collect wastewater from bathroom sinks, showers, bathtubs, clothes
washing machines, and laundry sinks and to direct it towards the storage tank. Any
alterations in the piping must be approved by the local building inspector. It is
necessary to consult with the local building, heath or water department to find out
what restrictions apply.
The blackwater piping from toilets and kitchen sink remains plumbed to the sewer
line or septic tank disposal system. In retrofit situations involving buildings with slab
foundations, the graywater that can be recovered may be limited to the clothes
washing machine. Most drain pipes are buried beneath the slab and. thus, are not
easily accessible without a significant additional expense. Those buildings with
perimeter foundations permit access to graywater piping from the crawl space and,
thus, most of the graywater is recoverable.
Treatment Methods
A variety of methods can be used for treating the graywater for reuse purposes. These
include the use of: mediajiltration; collection and settling; biological treatment units:
reverse osmosis; sedtmentCLtion/jatration; and physical/chemical treatment. Depending
on the graywater source, application, recycling scheme and economics, one method
may be more appropriate than the other.
Media Filtration
Several different types of media can be used in graywater filtration. These include:
nylon or cloth filters, sandJUters, and rack or grate filters. Each is described briefly
below.
Nylon or Cloth Filter: The nylon or cloth filter system typically consists of a filter bag
connected to the graywater inlet pipe in a tank. The graywater is passed through the
filter media (which collects lint and hair) and collected within the tank. Once filtered
graywater is collected, the treated graywater typically then is pumped to a mlni-
leachfield for irrigation purposes. This system currently is recommended by the City of
Santa Barbara and City of San Luis Obispo in California for use in recovering washing
machine water for irrigation purposes.
m-3
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Sand Filter: The sand filter system consists of a sand- and rock-filled tank with an
underdrain system (Figure 3-2). Graywater is poured onto splash plates. The
graywater then seeps through the filter media, receiving both physical and biological
treatment. Biological treatment occurs by bacterial growth on the sand which breaks
down organic matter and extracts nutrients from wastewater to support growth.
Physical filteririfremoves solids and results in clarification of the wastewater. The
filtered graywater then is collected and transported via an underdrain system for
reuse. A pea gravel filter is similar to a sand filter except that it uses pea-sized stone
instead of sand for filtration.
Greywater Inlet
Sand—3 ft.
Peag ravel
Medium
Gravel
arge ,
Gravel •
Greywater
Inlet—^
Splash Plates
Sand
Gravel p"3ravei
Filtered Water
Rltered Water
Figure 3-2: Sand Filters
Source: Reference #9
The University of Wisconsin (9, 22) evaluated sand filters for treating graywater septic
tank effluent and obtained 98 percent removal of biological oxygen demand (BOD) and
greater than 75 percent removal of chemical oxygen demand (COD), total suspended
solids (TSS). and volatile suspended solids (VSS). The study concluded that
intermittent sand filtration of graywater septic tank effluent resulted in almost
complete nitrification. Effluent phosphorus levels largely remained unchanged.
Diatomaceous Earth Filter: Diatomaceous earth filters have been commonly used to filter
water for swimming pools and spas. They also can be used for treating graywater.
Cohen and Wesner (19) evaluated the use of a diatomaceous filter system with a
recycle line to treat graywater and concluded that turbidity and suspended solids were
reduced to 13 to 30 mg/1 and 15 to 25 mg/1, respectively. Hypes. Batten, and Wilktas
(20) modified Cohen and Wesner*s filter in the recycle line and reported reductions of
turbidity to 29 mg/1, TOC by 19 percent, and coliforms by 100 percent.
Rack or Grate Filter: The primary function of the rack or grate filter is to remove
particulate matter from the graywater. The graywater system typically consists of a
rack or grate filter, piping, and a tank. Graywater is passed through the filter media
into the tank. The graywater then is either further treated or reused.
m-4
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Collection and Settling
Collection and settling systems employ techniques commonly used for treatment of
combined graywater and blackwater. One example of this system involves the use of a
septic tank. Septic tanks provide for the retention of the solids portion of graywater
and anaerobic treatment of the liquid generally for three to five days. The septic tank
allows solids from incoming graywater to settle to the bottom of the tank, forming a
sludge layer. Certain materials, such as grease and hair, float to the top of the liquid
in the tank and form a floating scum layer. This scum layer is held in the tank by
baffles. The liquid effluent flows through an outlet pipe for further treatment or reuse.
The University of Wisconsin (21) evaluated the performance of different sized septic
tanks (500- and 1.000-gallon) and found that the larger tank achieved an additional
17 percent reduction in BOD and 15 percent reduction in COD. with little further
reduction of solids or nutrients.
Brandes (11) and Olsone et al (22) evaluated graywater septic tank effluent
characteristics based upon extensive data collection programs. Brandes (11)
concluded that time intervals that could be allowed between graywater septic tank
cleanouts were about eight to ten times longer than for normal household septic tanks
treating combined wastewaters.
Biological Treatment Units
Biological treatment of graywater is a means of reducing both soluble and insoluble
organic contaminants. These units usually consist of three chambers: pre-settling,
aeration, and final settling (with sludge return). Graywater first flows into the pre-
settling chamber where gross solids settle out. The effluent from the pre-settling
chamber then flows into the aeration chamber where biological action reduces soluble
organics. The effluent then flows into the final settling chamber where biologically
active solids settle out. Biological treatment units usually are used in large
commercial applications.
Reverse Osmosis
Reverse osmosis (RO) units have been tested for graywater treatment. The RO system
consists of storage tanks, pumps, filtration units, and a reverse osmosis module.
Graywater is collected and stored in a storage tank (Figure 3-3). The graywater then is
pumped through filtration unit(s). The filtered graywater them flows to a second tank,
and is pumped to the reverse osmosis unit The filtered graywater which passes
through the reverse osmosis unit is stored for reuse/disposal.
Hypes, Batten, and Wilkins (23) examined the performance of a sedimentation/reverse
osmosis unit to treat laundry and shower wastewater and reported reductions in total
solids (TS) and total organic carbon (TOG) of 88 percent and 93 percent, respectively.
The study concluded that the effluent water met all Public Health Service drinking
water requirements except for carbon chloroform extract (CCE), methylene blue -
active substances (MBAS), and phenols.
m-5
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Greywater Influent
Storage
TanK
•>.
Filtration
Unit
>
Storage
Tank
Readable Fraction
Sludge Removal
Reuse
Figure 3-3: Reverse Osmosis
Source: Reference #9
Sedimentation/Filtration
A variety of different designs of sedimentation/filtration treatment schemes exist.
These systems are basically the same with minor variations in sedimentation basin
design, filter media, and recycling rates. The basic design consists of a conically
shaped storage/settling tank and a filter. The shape of this tank, along with a bottom
drain, simplifies sludge removal. The storage tank also should be equipped with an
overflow fitting and low-level control to assure adequate water supply at all times. A
variety of filters can be used. Cartridge filters are very convenient because they are
discarded when spent. Diatomaceous earth filters also have been used. Activated
charcoal filters have been used in conjunction with diatomaceous earth filters. The
treated graywater is disinfected and then reused/disposed (Figure 3-4).
5'iywur mftmtx
imirmtonn Stongf)
CARTRIDGE FILTER
Oiwrtitan 0,-BiBf BKVCT
Griywiw lnlhmn_^ ,1 J, ""
coHMMfl Iliw
H| ChaaiM* H»r).4 Knit (Or intirninnji,
1 T ' Sloragt)
BiOwun roSnm
OIATOMACEOUS EARTH FILTER
StrraMr influtnl-
-ijtto^^K""' 'CSS"""1"
Siud«t Rtmov* ACTIVATED CHARCOAL FILTER 9«»«"» Oisooui
Figure 3-4: Sedimentation/Filtration Systems
Source: Reference #9
IH-6
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Physical/Chemical Treatment
In this process, graywater flows through a rapid mix tank where polymer and
activated carbon are added. The mixture of graywater, polymer, and"carbon flows to a
clarifier where a sludge conditioner is added. After settling, the supernatant then is
disinfected and-passed through a diatomaceous earth filter. The treated graywater
then is ready for reuse for toilet flushing or lawn watering.
Lent (24) used a chemical coagulation with polymer and activated charcoal system to
treat graywater. He reported an effluent with BOD, suspended solids, and turbidity
removal exceeding 90 percent.
Disinfection Techniques
Four different techniques have been used to treat graywater for reuse within or
outside buildings. These techniques involve: ultraviolet irradiation, ozone, chlorine, and
iodine. A brief description of each disinfection technique follows.
Ultraviolet Irradiation
Ultraviolet irradiation (UV) disinfection involves passing graywater under a lamp
which emits light within the ultraviolet range that effectively kills any microorganisms.
For effective disinfection by UV, the graywater must be free of particulate matter
which could prevent the UV radiation from reaching and destroying the
microorganisms.
Research performed at the University of Wisconsin (25) and by Hoover, McNalfy, and
Goldsmith (26) investigated the performance of disinfecting sand filter effluent and
aerobic unit effluent with UV. Their findings revealed that fecal coliform, total
coliform, fecal streptococci, total, bacteria, pseudomonas aeruginosa. and poliovirus I
populations were reduced by at least 97 percent in all cases.
Ozone
Ozone is a highly reactive form of oxygen. It is formed naturally by the short wave
ultraviolet light of the sun reacting with oxygen in the upper atmosphere. The ozone
layer protects us from receiving the harmful shortwave radiation from the sun by
absorbing it.
As shown in Table 3-1. ozone is a powerful oxidant that can be used safely for
disinfection of graywater. When combined with ultraviolet light, ozone forms hydroxyl
radicals, which have even a higher oxidation power. For graywater treatment, it has
the ability to destroy algae, bacteria, and viruses and to oxidize most organic and
inorganic contaminants.
m-7
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Table 3-1: Relative Oxidation Power of Oxidizing Species
Species
Fluorine
Hydroxyl Radical
Atomic Oxygen
OZONE
Hydrogen Peroxide
Perhydroxyl Radicals
Hypochlorous
Chlorine
Oxidation Potential
(Volts)
3.06
2.80
2.42
2.07
1.77
1.70
1.49
1.36
Relative Oxidation
Power
2.25
2.05
1.78
1.52
1.30
1.25
1.10
1.00
'Based on Chlorine as reference (=1.00)
Source: Reference #27
Large doses of ozone can be harmful to humans. The U.S. Department of Labor,
Occupational Safety and Health Administration (OSHA) has set a limit of 0.1 ppm in
air as the maximum average exposure for a single 8-hour shift in a 40-hour work
week. A person does not become irritated from ozone until the concentration reaches
over 100 ppm for one minute. The toxic level Is over 1000 ppm for one minute. A well
designed ozone system for graywater disinfection, however, does not produce ozone
concentrations that are harmful or irritating to humans.
Chlorine
Chlorine in the form of tablets is the most commonly used method of graywater
disinfection currently in residential applications. Chlorine tablets are dissolved In the
effluent storage tank. Adequate time (about 30 minutes) must be given for bacterial
reductions to occur.
Saver (28) at the University of Wisconsin used a dry feed chlorine unit to disinfect
sand filter effluent and reported greater than 90 percent reductions in fecal coliform.
total coliform. fecal streptococci, total bacteria, and pseudomonas aeruginosa
populations.
Iodine
Iodine crystal units operate in the same manner as chlorine tablets. Due to the limited
solubility of iodine, a dosing pump is required to assure adequate pressure and flow of
wastewater for iodine crystal dissolution.
IH-8
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Budde, Nehm. and Boyle (29) Investigated iodine crystal units to disinfect treatment
plant effluent and reported that greater than 98 percent reductions in coliform
bacteria occurred when using a 5 mg/1 or greater iodine dose.
Irrigation Methods -
Graywater use for landscape irrigation has been approved in several states. However.
approved use in all cases is limited to the use of sub-surface irrigation system only.
Two types of sub-surface irrigation systems have been used: a mini-leachfleld or a
drip^irrigation system. Each system is described briefly below.
Mlni-Leachfleld
A mini-leachfield typically is created by digging trench along the dripline (the outer
edge of the foliage) and filled with gravel 1 within 4 inches of the surface, as shown in
Figures 3-5 and 3-6. The gravel is covered with building paper or weed-stop matting
before filling the trench with soil. If the soil is able to infiltrate down into the gravel,
the mini-leachfield will quickly clog and the water will be forced to the surface,
causing pooling.
Line From Surge Tank
To Next Tree
#2
#3
#4
#5
#6
#7
#8
1/2" polyethylene irrigation hose
T coupler
drip irrigation ball valve
right angle coupler
clay (or plastic) pot
straight coupler (used inside pot)
mini-leachfield (1" round gravel)
weed-stop matting or building paper
Figure 3-5: Mini-Leachfield Design
Source: Reference #30
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Drip irrigation
Although the mlni-leachfield design is the currently approved method in states and
counties where on-site graywater recycling is approved for landscape irrigation, the
subsurface drip irrigation method also is used. However, compatibility of graywater
and subsurface-drip technology is unknown. Recognizing this, the Ad-Hoc Graywater
Committee in California is undertaking a multi-year study of their technology under
real world conditions. A work plan for this study is included in Appendix A.
A typical drip irrigation system is shown in Figure 3-7. The treated effluent pumped
from the tank passes through a mesh screen filter, control valve, and a pressure
regulator. The header line has a flush valve/vacuum breaker and feeds the driplines.
The driplines employ wide passage turbulent flow path/emitters of various types:
inline or in-pipe emitters pre-inserted at regular spacings in the pipe for median
strips, narrow hedges or lawns; mini-line or button emitters to wrap around trees,
plants or individual bushes: and pressure compensating button emitters for
pronounced slopes. Driplines typically are buried below ground 4 to 12 inches deep,
below cultivation depth. The ends of the driplines can be connected together at the
end to facilitate flushing. An automatic flushing valve/vacuum breaker is placed at
the end of the lines. The vacuum breaker/flush valves are placed in a gravel-filled
valve box below ground. To control several irrigation sectors, an irrigation timer or an
alternating valve is sometimes used.
A major concern and problem with drip irrigation has always been the risk of clogging
of emitters, even when using fresh water. Roots seeking moisture and nutrients have
been known to enter drip irrigation lines and block them in the same manner as they
enter sewer pipes.
To minimize this problem, emitters are currently available that use turbulent flow long
path design. These emitters operate at a flow rate of 1 to 2 GPH with 0.06 to 0.07 inch
orifices. The emitters usually are made out of polypropylene and are resistent to most
acids and substances likely to be found in domestic wastewater.
CURRENTLY AVAILABLE TECHNOLOGIES
Many types of graywater systems currently are available in the marketplace. A brief
discussion of each known system, including system description, application, testing
status, cost, and maintenance, is provided at the end of this section.
CURRENT AND POTENTIAL APPLICATIONS
Graywater recycling is an important demand-side management strategy. It can result
in significant water savings in all types of buildings. In a typical residence, it can
displace 50 percent of the current use of potable water. Although the issue of water
conservation is pertinent world-wide, it is receiving increasing attention in the United
States in areas where the prospect of water shortages is most imminent.
m-11
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Flusn line ,
Compresion aaapter
Dnpimes -.-^^
a
Moisture .
sensor ^
(optional) M
Emitters
Treated
effluent
Screen y
Finer water meter
(optional)
V
Pressure
regulator
Timer
- Valve
Box
Figure 3-7: Sub-surface Drip Irrigation System
Source: Reference #32
Graywater recycling applications currently can be found in several states, including
California. Arizona, and South Dakota. Most of these applications have been in
residences In both, urban and rural communities experiencing persistent drought
conditions. Hie potential market for graywater recycling is. however, not limited to the
above mentioned states. In addition to these states, on-site graywater recycling -
systems represent a water conservation and peak reduction strategy in other states or
regions having arid or semi-arid climates (e.g., Nevada. New Mexico, and portions of
Colorado. Washington. Oregon. Texas. Kansas. Idaho. Montana. Nebraska, North
Dakota. Utah, and Wyoming). Coastal areas in other states experiencing water
shortages (e.g.. North Carolina, Massachusetts. South Carolina, and Florida) are also
potential markets for graywater systems, as are all of the other major urban areas in
the country where sewage treatment plants are already overloaded and expansion
possibilities are constrained due to limited availability of funds.
Because graywater recycling can help reduce peak demand, conserve municipal water
supplies and delay capital expenditures for expansion of municipal potable water
treatment and distribution systems, they could be an element of wastewater plans in
every state, city, and municipality. Even though there currently are only a few
in-12
-------
CASE IN POINT
HOTEL ESTIMATES $10,000/YEAR SAVINGS
WITH GRAYWATER RECYCLING SYSTEM
The Apple Fanrrtnrr & Restaurant in San Luis Obispo, California expects to lower its
water bill and sewer bill by about $5.000 per year each with the installation of a
graywater recycling system. Payback is expected in 1.5 to 2 years. The 7-room luxury
hotel has two 50-pound commercial laundry washers. Each washer is cycled about 14
times per day. Each cycle generates approximately 150 gallons of discharged water. A
total of 4,200 gallons of discharged water is generated by both washers. Since all
laundry is bleached by the automatic injection of 100 PPM of chlorine, the resulting
discharged water is totally free of bacteria. The water is quite clear, but lint and suds
are suspended on the surface. The hotel's adjacent free standing, 250-seat restaurant
has six pressure-flush toilets in the public restrooms and two tank-type toilets in the
employee restrooms.
The graywater recycling system collects and treats the discharged laundry water for
reuse for toilet flushing in the public and employee restrooms. It consists of PVC
piping, surge tank, pump, two filter media, and chlorinator. The hotel's laundry
machines are connected to a 75-gallon surge tank on the floor adjacent to the
machines by 3" gravity-fed drains. The discharged water is filtered immediately
through two pair of panty hose which are attached to the drain line. A transfer pump
is mounted on top of the tank and is controlled by a float switch. This pump transfers
the water through a 2 1/2" PVC line approximately 300 feet to a 1,250-gallon plastic
storage tank where another panty hose filter is attached. A siphon connects the first
1,250-gallon tank to a second tank. A 100 micron filter bag is attached to the outflow
side of the siphon. A multi-stage Jacuzzi well pump is located in the second tank
which pressurizes 2 85 gallon bladder tanks located on the roof above the restrooms.
A standard tablet-type spa chlorinator is attached to the top of the first storage tank
with a supply incoming from the pressurized side of the system. The flow can be
adjusted to result in the 1 PPM residual chlorine required by the County Health
Department in the final supply line to the toilets. A test valve was required for
convenient periodic testing. The second tank has a potable water supply connected to
the top of the tank with a double diameter air cap. This supply is controlled by a float
valve to add water when demand exceeds supply.
The water in the toilet bowls is indistinguishable from potable water. When flushed,
residual detergent causes mild foaming, but the foam dissipates shortly after
completion of the cycle. Warning signs required by the local health department were
placed over each fixture. They also included a brief explanation of the system and the
amount of water being saved.
This system has been well-received at the hotel. Management has received some
extremely positive comments about the system and no complaints to date. The system
requires very little maintenance. This includes a periodic backwashing of the system,
replacement of the filter media, and replacement of the chlorine tablets.
IH-13
-------
applications of graywater recycling systems nationwide, this could change in the
future, due to persistent potable water shortages, overloaded sewage treatment
facilities, and strict environmental regulations for water use and disposal.
APPLlCATIOr^CONSIDERATIONS FOR IRRIGATION
t
Because of the nature of graywater, the unsafe, indiscriminate application of
graywater can be hazardous. Graywater should not be placed on anything eaten or
allowed to collect on the surface of the ground or run off the property. Several factors
must be considered In applying a graywater recycling system for Irrigation purposes.
These factors include: graywater irrigation needs and. production capacity, soil
absorption capacity and criteria, graywater salinity and make-up water use, system
location, wastewater heat recovery, and dual wastewater piping requirements Each
factor Is described briefly below.
Gravwater Irrigation Needs and Production Capacity
For Irrigation purposes, it is important to determine which trees, shrubs, and plants
are to be irrigated with graywater. While many plants are suitable for subsurface
Irrigation using graywater. certain shade-loving, acid-loving plants are not. Table 3-2
lists the plants suitable and not suitable for graywater irrigation.
Table 3-2: Plants Suitable and Not Suitable for Graywater Irrigation
Not SulUbto
Ornamental trees and shrubs
Mott flowtre and other
ornamental ground cover
Lawns
Fruit trees
Rhododendrons
Bleeding Hearts (Dicentra)
Oxals (Wood Sorrel)
Primroses
PhBodendrons
Azeteas
Violets
Impatiens
Hydrangeas
Camellias
Ferns
Foxgloves
Gardenias
Begonias
Source: Reference #24 and #25
The total weekly water requirements typically are estimated using the following rules
of thumb:
• Mature fruit tree = 75 gallons/week
• Shade trees (pines, etc.) = 50 gallons/week
• Large shrubs = 10 gallons/week
General criteria used for estimating the weekly graywater production in a residence is
as follows:
• Determine gallons per minute by showerhead flow and multiply by the
showering time per person.
m-14
-------
• • Add 20 gallons for each bath taken in place of a shower.
• Add 14 gallons to the weekly total for each sink in the system.
• Add 20 gallons per load clothes washing machines times number of loads per
week.
The total amount of graywater production (in gallons) then can be figured.
For graywater production in commercial buildings, estimates can be developed using
data provided for fixture flows in the standard plumbing code.
Soil Absorption Capacity and Criteria
To avoid water surfacing in difficult soils, the effluent loading rate should be set
according to the type of soil. Some localities require that the soil in which the
irrigation distribution system is to be placed in must meet certain criteria. For
example. Table 3-3 lists design criteria for six typical soils as required by the Water
Conservation Office of the California Department of Water Resources.
Table 3-3: Design Criteria of Six Typical Soil
Minimum ft, of leaching/irrigation area Maximum absorption capacity gals, par
perl 00 gallons of estimated graywater ft1 of teaching/irrigation area for a 24-
Typa of Soil discharge par day hour period
Coarse sand or gravel 20 5
Find sand 25 4
Sandy loam 40 2.5
Sandy day 60 1.66
Clay with considerable sand or gravel 90 1.10
Clay with small amount of sand or gravel 120 0.83
Source: Reference #18
Gravwater Salinity and Make-up Water Use
One of the limitations in the use of graywater for irrigation is the high salinity content
usually present in graywater. In particular, water that has been softened and the use
of detergents tends to raise the sodium content of the water and consequently makes
it less desirable for irrigation. A high sodium content also tends to "seal" the soil.
It is important to check the types of plants that are being irrigated to see if any are
more or less tolerant to irrigation with higher salinity water when designing the
system. If there is a deficit in the amount of graywater produced or higher salinity
levels are a problem, fresh make-up water can be added to dilute the salinity prior to
irrigation.
IH-15
-------
System Location
Some cities and counties which allow graywater systems for irrigation purposes
require that certain minimum distances be kept between certain graywater system
components and_buildings. streams, etc. Table 3-4 indicates recommended minimum
distances for graywater system components locations as required by San Luis Obisno
County in California. H
Table 3-4: Recommended Minimum Distance for Graywater System Location1
Minimum Horizontal Distance (ft) In Clear Required From:
Buildings or structures2
Property line adjoining private property
Water (supply watts9
Streams and lakes3
Seepaoe pits and cesspools
Disposal field & 100% expansion area
Septic tank
On-site domestic water service line
Pressure public water main
Surge Tank
Oft1
5
50
50
5
5
0
S
10
1 wln*4fm>« Cl^IaJ
iim ganon rloid
2ft4
5
100
SO*
5
47
5
5
10*
'When irrigation fields are installed in sloping ground, the minimum horizontal
distance between any part of the distribution system and ground surfece shall be 15
feet.
2Including porches and steps, whether covered or uncovered, breezeways, roofed
patios, car ports, covered walks, covered driveways, and similar structures
Underground tanks shall be 5 feet from structures.
4Assume 45 degree angle.
sWhere special hazards are involved, the distance also shall be increased as mav be
directed by the Administrative Authority.
6There minimum clear horizontal distances also shall apply between irrigation field
and the ocean mean higher tide line.
7Plus two feet for each additional foot of depth in excess of one foot below the bottom
of the drain line.
BFor parallel construction/for crossings, approval by the Administrative Authority
shall be required.
Source: Reference #18
Wastewater Heat Recovery
Because a graywater recycling system collects used wastewater in a separate piping
system, it is possible to extract waste heat from the graywater. For example, graywater
IH-16
-------
from clothes washing machines is very warm. Heat exchange elements can be
installed in the graywater system piping to recover the heat that otherwise would be
lost. Plate-type heat exchangers have good heat transfer characteristics, but foul
quickly. Steel and tube heat exchangers may have a problem with clogging when dirty
water is in the tubes. Roll-away shell-type heat exchangers are specifically designed
for this type of ^service and can be easily cleaned. Recovered heat can be used to
preheat water in domestic water heaters (Figure 3-8) or for heating hot water systems.
Heat recovery can reduce overall building energy consumption, as well as operating
costs. Another example of wastewater heat recovery is shown in Figure 3-9. In this
application involving graywater from a commercial laundry facility, heat is recovered
through heat exchangers for preheating hot water for the clothes washers and
domestic water before reusing graywater in urinals and toilets.
Warm Water to * '.
water Msattr
Heat Excn.
Waste Water
Cire. Pumo
waw
; Waste Water
to Gr«y Waitr
Storage Tank
or w Sewer
Figure 3-8: Wastewater Heat Recovery
Source: Reference #33
Dual Wastewater Piping Requirements
Graywater recycling systems require the use of dual wastewater piping systems-
(Figure 3-10). Although new buildings can easily employ dual plumbing systems at
very little extra cost, plumbing modifications may be cost prohibitive and difficult to
make in a retrofit situation. In such cases, however, it may be more cost effective to
direct graywater to a single source such as an ornamental pond or a cooling tower. In
all cases, however, the system should be designed so that their is no potential for
cross contamination of the potable water supply. The recycled graywater piping
should be color-coded and use different materials of construction (e.g., PVC) as
approved by local building codes.
IH-17
-------
• *•»»•
rim
I9!MW p—
4£P**J
Figure 3-9: Waste Heat Recovery System for Commercial Laundry Facility
Source: Reference #33
Pataon Wiw
/•Suootv Systtm
Jo«AcJuatea
Fill Vaivt
Fin Cue
Coliaown
Sys»m
Grey water
X Suowy Syitwn
Watir
Ctoiit
T
Unnai
Row Own
\
wanr
tM
I
waaft«r
TO
1 Sarrtary
> Sanitary Seww
CoiMetifln SytMm
Figure 3-10: Graywater Dual Piping Systems
Source: Reference #33
IH-18
-------
INSTALLATION CONSIDERATIONS
Graywater systems must be installed In accordance with local plumbing codes. They
should be installed by professional licensed plumbing contractors, who are familiar
with currently available technologies, the local plumbing codes, and requirements of
the local health departments.
The installation of a graywater system requires the retrofitting of existing plumbing.
Any modifications or alternations of a plumbing system must be approved by local
building departments. Appropriate number of copies of the plot plan indicating the
location(s) of the fixture(s) to be included in the system and the area(s) of graywater
distribution must be submitted to the local agency along with a completed application
to the community development department.
All counties and cities where graywater recycling is currently permitted require their
building inspectors to inspect sites and. after the installation, to assume compliance
and proper operation.
Code authorities may require a method of distinguishing the potable (drinking) water
and the graywater supply systems. These methods may include extensive labelling of
the system and/or use of different piping materials, such as copper type "1" for the
potable system and PVC for the graywater system. If PVC is utilized for graywater
supply piping, flow velocity should not exceed six feet per second because of sound
problems inherent with PVC. All graywater outlets must be provided with signage
stating that the outlets dispense non-potable water. Proper separation, using reduced
pressure backflow preventers, must be provided between potable water and graywater
supply systems. Codes also may require injecting a biodegradable dye for easy
discrimination between two systems.
OPERATION AND MAINTENANCE CONSIDERATIONS
As discussed in Section II, graywater may carry varying concentrations of potentially
disease-causing organisms. However, with proper care and treatment, graywater can
be used safely. The primary health risk concern is that pathogenic organisms in the
graywater might come into human or animal contact and thereby spread disease. This
risk can be significantly reduced by following either of two approaches.
One approach is to limit the level of pathogens in graywater by adequate treatment or
by avoiding water containing any fecal matter (e.g., from the toilet or from washing
soiled diapers) from being mixed with the graywater system.
•The other approach is to prevent human and animal exposure to the graywater. This
can be accomplished by not collecting or storing graywater in an open container and
by not applying it through a spraying device. Vegetable gardens, lawns, and any other
surfaces that humans and animals may come into contact with should not be
irrigated with graywater. Mini-leachfleld of drip-irrigation systems can be installed to
irrigate shrubs, mature fruit trees, and groundcover.
ffl-19
-------
A variety of soaps and cleaning products contain chemical that may be toxic to plants.
people: they must not be used in conjunction with a graywater recycling system. For
example, powdered detergents and soaps may contain sodium compounds which can
build-up in the soil. -Excess sodium levels can interfere in the soil's ability to absorb
water and can directly damage plants. Soaps and cleaners that can damage plants
include detergents that contain boron, borax, chlorine, peroxygen. sodium perborate.
petroleum distillates, alkylbenene. sodium trypochlorite. bleaches, or softeners.
Labels on soap and cleaner containers generally do not provide any information as to
their plant poisoning and soil damaging contents. However. George Brookbank, a
researcher at the Ebctension Garden Center of the University of Arizona, published his
analysis of the chemical composition of many commercial detergents for sodium.
boron, and phosphate content, as well as their conductivity and alkalinity levels.
Table 3-5 summarizes the results of the analysis.
Still, some soaps that can be used safely with graywater systems are commercially
available. Several manufacturers have developed biocompatlble cleaners which are
specially designed and tested for improved plant irrigation. These cleaners biodegrade
into plant nutrients. They contain no sodium, chlorine, or boron and do not adversely
affect soil pH or structure.
Rain or excessive irrigation can saturate the soil above the distribution system and
cause graywater to pool on the surface. Turning the graywater system off and
diverting the graywater to the sanitary sewer line during "rainy" periods can avoid
problem pooling from occurring.
Graywater systems require regular maintenance. Some common maintenance
procedures are: inspecting the system for leaks and blockages: bimonthly cleaning
and replacement of the filter, replacement of the disinfectant, ensuring proper
operation of controls: and periodic flushing of the entire system.
POTENTIAL IMPACTS OF GRAYWATER USE ON THE SEWER SYSTEM
Some individuals are concerned that the combined use of graywater and ultra-low
flow flush toilets in buildings could lead to accumulation of sediment in sewer pipes.
. r." re slopes are minimal. No evidence was found in the literature reviewed for this
report that corroborated this fact. Nonetheless, the potential should be studied under
controlled pilot projects.
There also is a concern that decreased flows to sewage treatment facilities would .
reduce the amount of effluent discharged from the sewage treatment plant and
increase the concentration of pollutants present in that effluent (34). However, several
researchers (34) believe that a gradual, continuous reduction in sewage flow, due to
increased graywater recycling for instance, would actually benefit the environment
receiving sewage plant effluent discharges. These researchers also indicate that
m-20
-------
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malfunctioning of wastewater treatment systems can be avoided and substantial
savings in costs of water supply and wastewater treatment can be anticipated by
preplanned water conservation programs as a result of increased use of graywater.
m-22
-------
Clearstream Wastewater System
Clearstream Wastewater Systems, Inc.
P.O. Box 705, SHsbee, Texas 77656
Jerry McKinney
409-385-1395
SYSTEM DESCRIPTION
Clearstream Wastewater Systems manufactures a wastewater treatment unit which
through aeration and clarification provides an environment for aerobic bacteria and
other microorganisms that converts incoming wastewater into reusable water. It can
be used separately (Figure 3-11) or in combination with a septic tank (typically 300-
500 gallons) which provides for anaerobic primary treatment (Figure 3-12).
4.TAMPER RESISTANT BOLTS
WASTEWATER TREATMENT UNIT
ACCESS COVER
ALARM FLOAT
,5- — OUTLET INVERT
4-i-
TERTIARV FILTER
AIR DROP LINE
SLUDGE DEFLECTOR
ALARM PANEL
•;— »4- i I/is-
Figure 3-11: Clearstream Wastewater Treatment System
APPLICATION
The Clearstream Wastewater System is currently being used in a few single-family
residences located in Texas, Louisiana. Georgia, and Florida. Typical use of the
treated graywater is for spray or drip irrigation of lawns, pastures, landscape beds,
and golf courses. With additional accessories, the effluent can be used for several
other non-potable water applications.
m-23
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Wastewater
Aerooic
unit
Chlormator
Sampling Treated
Effluent
level
switches
pump
To subsurface
drip system
Dosing
chamber
Air compressor 1
Figure 3-12: Clearstream Wastewater Treatment System wrth Septic Tank
TESTING STATUS
This system has been tested by the National Sanitary Foundation and has been given
NSF Class 1 approval.
The Installed cost of this system (including drip irrigation) typically ranges from
$4.000 to $5.000.
MAINTENANCE
The manufacturer of this system states that the following periodic maintenance will be
required.
• Repair or replacement of the aerator (2 to 10 years)
• Cleaning of filters on aerator (6 mos. to 2 years)
• Breaking up scum in clarifler (6 mos. to 2 years)
• Pumping sludge from aerat on tank (2 to 5 years)
• Pumping sludge from trash trap (2 to 5 years)
• Checking aeration difiusers (annually)
* Back washing tertiary filter (annually)
m-24
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The Grey Water Recycler
King O'Lawn
P.O. Box 1068
10127 Adell Avenue
Southgate, California 90280
Thomas Kristy
SYSTEM DESCRIPTION
This system consists of a polyeurethane tank (120-gallon capacity), bacteria control
system, and water filter. It connects to the discharge line from the clothes washer
where it filters and sanitizes incoming water, then deposits it into the holding tank.
When the tank is full, excess graywater is sent down the drain. A garden hose
connected at the base of the tank can be used for applying water to the landscape.
APPLICATION
The system currently is being marketed for single-family residential applications.
TESTING STATUS
This system is one of eight systems currently being tested by the City of Los Angeles.
Otherwise, no testing has been performed to date.
COST
The installed cost of this system is about $800.
MAINTENANCE
Although no maintenance requirements were provided with information from the
distributor, standard cleaning and repair/replacement practices should apply.
IH-25
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Water Recycler
Ken Leek
1973 Cordilleras Road
Redwood City, California 94062
Ken Leek
415-369-7010
SYSTEM DESCRIPTION
In this system, graywater is first passed thrcugh a wire mesh paniculate filter then
passed through a thermostatically-controllec. electric heater which raises water
temperature to 90F. Next, the WE.ECT passes through a sediment filter, carbon filter
color filter and is treated by ultraviolet irradiation, before it is collected in the storage
tank. The water is pumped to landscape irrigation system.
APPLICATION
The primary application of this system is residential. Because the system is very new
to the marketplace, there are no installations on customer premises. However the
developer of the system has an installation of a prototype in his home that reclaims
graywater from a clothes washing machine.
TESTING STATUS
The developer plans on having the Water Recycler tested and certified by the National
Sanitation Foundation. Sequoia Analytical in Redwood City has performed some initial
bacteriological and chemical analyses of graywater samples taken from the developer's
own home.
The installed cost currently is estimated to be $2,900. However, the cost is likely to
decrease to about $1,000 if demand for Water Recycler increases significantly.
MAINTENANCE
Although no maintenance requirements were provided with information from the
distributor, standard cleaning and repair/replacement practices should apply.
m-26
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Automatic Grey Water Apparatus
AGWA Systems, Inc.
801 South Flower Street
Burbank, California 91502
Gary J. Stewart
800-GREY-H20
SYSTEM DESCRIPTION
This system uses a dual tank system consisting of a gravity-fed tank where graywater
drains and a storage tank where water is stored. It requires an electronic controller
that constantly monitors the system and allows it to work in unison with the
customer's existing irrigation system. Electronics also allow a special sand filter
specifically designed for this system to backwash daily, weekly, or monthly depending
upon the amount of use the system gets.
APPLICATION
The current application of this system is residential. However, it can be used in small
commercial buildings.
TESTING STATUS
This system is one of eight systems currently being tested by the City of Los Angeles.
Otherwise, no other testing has been performed to date.
COST
The installed cost for a two bathroom residence is about $3.200. Because this system
is very new to the marketplace, it is not known how long the sand in the filter will last
under various conditions. However, it is contemplated that a service contract involving
periodic testing of the system and a new canister of sand will cost about $75.
MAINTENANCE
System maintenance includes: changing of the filter bag (costs approximately $40),
turning of the irrigation valves, ar-d manually flushing the subsurface irrigation
system (if the system uses subsurface drip irrigation, it needs to be flushed every six
months).
m-27
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Cycle H20
Homestead Utilities
HC62, Box 3812
Camp Verde, Arizona 86322
Anton Van Puffeian
800-292-5340
SYSTEM DESCRIPTION
This system recovers graywater from tubs, showers, and clothes washing machines
and passes it through a filter to a tank. The graywater from the tank then is pumped
to the toilet tank or flushing where it used instead of potable water.
APPLICATION
This system currently is being used in rural residences in Arizona.
TESTING STATUS
No testing has been performed to date.
The installed cost of this system in a new residence is about $500. whereas in an
existing residence where plumbing modifications must be made it is about $800.
MAINTENANCE
The distributor recommends chlorine bleach and one cup of white vinegar be added
periodically to dissipate soapy residue in the system.
IH-28
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Fluid Systems
Ted Adams
2800 Painted Cove Road
Santa Barbara, CA 93105
Ted Adams
805-964-1211
SYSTEM DESCRIPTION
This system (Figure 3-13) passes graywater through a polyester fiber filter, and then
deposits it in a tank. A pump distributes the graywater to an approved distribution
system. An overflow pipe discharges excess graywater.
galvanized
locking ring
\
lid
polyfoam seal
tank wail
pvc pipe & fittings
size determined by
application
100 micron filter
from graywater source
POLYTANK
D.O.T. approved
volume determined
by application
discharge
graywater
to approved
distribution
system
Figure 3-13: Fluid Systems' Graywater System
IH-29
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APPLICATION
This system currently being applied in the residential sector.
TESTING STATUS
No testing has been performed to date.
COST
The Installed cost of this system in a new residence is about $800.
MAINTENANCE
Depending on the system use. the polyester filter requires periodic
cleaning/replacement and the system requires flushing at least once a month.
IH-30
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Aquabank
Gray water Management
85097 Territorial Highway
Eugene, OR 97402
Tim Pope
503-687-0601
SYSTEM DESCRIPTION
This system currently is under development. It will use a 300 to 800 gallon tank with
a sand/gravel filter that will be backwashed every 6-8 hours. All controls will be
automatic. It will also utilize ozor.e treatment.
APPLICATION
The current application of this system is residential.
TESTING STATUS
No testing has been performed to date.
COST
The purchase cost of the system is $3.000. Installed cost is site-dependent, but will be
about $3.500.
MAINTENANCE
Although no maintenance requirements were provided with information from the
distributor, standard cleaning and repair/replacement practices should apply.
m-31
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HYDROX Grey Water Treatment System
The Watergroup, Inc.
681 Gatewood Lane
Sierra Madse, California 91024
Dale Sodlick
818-355-2623
SYSTEM DESCRIPTION
This system Is capable of treating graywater from a septic tank for irrigation of lawns,
washing walks, etc. It uses the trademarked HYDROX system (Figure 3-14) which
consists of an optional premier, a system pump, a captation chamber, and an
ultraviolet reactor plus appropriate piping and valves. The system is self-contained
and capable of being mounted in a dry well adjacent to the septic tank.
APPLICATION
This system is designed for application in residential and commercial buildings.
TESTING STATUS
No testing has been performed to date.
COST
No HYDROX Grey Water Treatment Systems have been sold as yet. The cost of this
system was not disclosed by the distributor.
MAINTENANCE
Except for the pump, this system employs no moving parts. UV lamp replacement is
required about every 14 months.
in-32
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Make-up Water
±
Residential
Effluent
Recycle to Septic Tank
Backflow Prevention Devi.
to Irrigation System
Filter
Hydrox System
Septic Tank with
Solid/Liquid Separation
Figure 3-14: Basic Schematic of Hydrox Grey Water Treatment System
m-33
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Watersave
Watersave
914 Prospect Avenue
Hermosa Beach, California 90254
Wayne Stanton
310-379-3575
SYSTEM DESCRIPTION
This system passes graywater through a fflttr. and then deposits it into a tank. A
pump distributes the graywater to an approved distribution system. An overflow nine
disposes of excess graywater. ^
APPLICATION
The current application of this system is single-family residential.
TESTING STATUSS
No testing has been performed to date.
The Installed cost of this system in a new residence is about $800 to $1.500.
MAINTENANCE
Although no maintenance requirements were provided with information from the
distributor, standard cleaning and repair/replacement practices should apply.
m-34
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Grey Water System
Grey Water Systems
438 Addison Avenue
Palo Alto, California 94301
Steve Bilson
415-324-1307
SYSTEM DESCRIPTION
This system passes graywater through a filter, and then deposits it into a tank. A
pump distributes the graywater to an approved distribution system. An overflow pipe
disposes of excess graywater.
APPLICATION
There have been about 36 installations of this system in residential buildings in San
Mateo. They are being considered for application in San Mateo/Santa Barbara
Counties.
TESTING STATUS
This system currently is being tested for water quality at the state environmental
laboratory.
COST
The installed cost of this system in a new residence is about $900.
MAINTENANCE
The only maintenance required is that the homeowner must change the filter once a
month.
m-ss
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AlasCan
AlasCan
Box 278
Healy, Alaska 99743
Clint Elston
907-683-2698
SYSTEM DESCRIPTION
In this system, graywater is passed from bathtubs, showers, clothes washing
machines, dishwashers, bathroom sinks, and kitchen sinks into a tank (Figure 3-15).
The tank is divided into the influent/preliminary, aeration and settling/effluent
chambers to clean the wastewater. The treated graywater may then be pumped to
other areas for reuse.
APPLICATION
This system has been designed for residential (single- and multi-family) and
commercial (hotels, motels, and small office buildings) applications.
TESTING STATUS
This system has been tested by the University of Alaska.
The installed cost of this system in a new residence is about $3.000.
MAINTENANCE
Although no maintenance requirements were provided with information from the
distributor, standard cleaning and repair/replacement practices should apply. ~
IH-36
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AlasCan Composting Tank
AlasCan Graywater Tank
Figure 3-15: AlasCan
m-37
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Water Maide
Water Maide
Desiderata Ranch
4617 County Road 2
Berthoud, Colorado 80513
Douglas R. Spence
303-772-9611
SYSTEM DESCRIPTION
This system collects the water drained from appliances, sinks and bathtubs (Figure 3-
16), then strains and superficially treats the water with a defoaming and deodorizing
agent, and returns it for use in toilets. It consists of a tank, a patented internal
filtering system, a chemical dispenser, and automated operating controls.
APPLICATION
Approximately 110 units of this system were installed in the mid-1980 in residential
buildings. It can be applied in new construction or retrofit of existing buildings.
TESTING STATUS
No testing has been performed to date.
COST
The installed cost for a new system is about $1.000 to $1.100. If multiple units are
involved, the installed cost may decrease to $700 to $800.
MAINTENANCE
General maintenance procedures involve opening a gate valve to allow sediment in the
Water Maide to exit into the sewer line, replenishing the chemical supply, and rinsing
or replacing the standard cartridge filter. These procedures should be performed
about one a month for family of four.
m-38
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Figure 3-16: Water Maide
in-39
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Gray Water Recycier
H. & E., Ltd
1555 North King Street
Hampton Virginia 23669
Nakley Anthony Risk
(804) 727-7733
SYSTEM DESCRIPTION
This system collects graywater from the shower/tub. The graywater is passed through
two activated carbon filters to remove hair and other pollutants, then distributed to a
tank. It is then gravity-fed to the landscape irrigation system.
APPLICATION
No installations of this system have been performed as yet. However, one installation
is being considered In New Mexico.
TESTING STATUS
No testing has been performed to date.
The Initial cost of this system is about $150. The manufacturer offers leasing for the
system at $10 per month including maintenance.
MAINTENANCE
The only maintenance requirement is that the filter must be changed every month.
m-40
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Cycle-Let Graywater Treatment and Recycling System
Thetford Systems, Inc.
P.O. Box 1285
Ann Arbor, Michigan 48106
John Irwin
800-521-3032
SYSTEM DESCRIPTION
This system uses biological treatment coupkd with membrane filters for complete
liquid/solid separation. It also involves the use of ultraviolet disinfection. Depending
upon the application, this system, also coulc employ activated carbon filtration.
APPLICATION
This system is designed primarily for hotel and motel applications and for use in
recreational facilities.
TESTING STATUS
This system has been tested and certified by the National Sanitation Foundation. It
meets the requirements of NSF Standard 41 for wastewater recycle/reuse.
The installed cost of this system varies with system size and flow capabilities. It is as
follows.
• 350 GPD flow -- $ 70.000
• 4200 GPD flow - $ 169.000
8500 GPD flow -- $ 313.000
This equipment, however, generally is leased to the building owner.
MAINTENANCE
Because the system typically is leased, operation and maintenance service is provided
by Thetford Systems. Inc. Annual O&M costs range from $l,000/month the 350 GPD
system to $3.750/month for the 8500 GPD system. Cost for electricity needed for
equipment operation is borne by the building owner. Annual energy consumption for
the three systems is estimated to be as follows.
350 GPD flow - 13.000 kWh/year
• 4200 GPD flow -- 60.000 kWh/year
8500 GPD flow - 95,000 kWh/year
IH-41
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Water Cycle
P.O. Box 1841
Santa Rosa, California 95402
Robert Kourick
707-874-2606
SYSTEM DESCRIPTION
The Water Cycle system recovers graywater from the clothes washing machine
passing it through a cloth filter into a plastic/fiberglass tank. The graywater is'
distributed to the irrigation system using gravity or a small pump.
APPLICATION
This system currently being applied in the residential sector.
TESTING STATUS
No testing has been performed to date.
COST
The installed cost for a pumped system for a clothes washing machine installation is
*p 5OO*
MAINTENANCE
Depending on the system use. the cloth filter requires periodic cleaning/replacement
and the system requires flushing at least once a month.
m-42
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Clivus Multrum, Inc.
21 Canal Street
Lawrence, Massachusetts 01840-1801
Carl Lindstrom
(508)794-1700
SYSTEM DESCRIPTION
A typical graywater system for a residence consists of a stretch filter (Figure 3-17) and
a graywater ejector pump. The filter catches the fibers and particles and the pump
distributes the graywater to the sub-surface irrigation field.
Figure 3-17: Stretch Filter Pretreatment
APPLICATION
This system can be used in residences primarily for sub-surface irrigation purposes.
TESTING STATUS
The system currently is being tested by the University of West Virginia. However, it
has not been tested by NSF.
COST
The installed cost of this system is $900.
MAINTENANCE
The stretch filter typically requires replacement about once a year. Maintenance can
IH-43
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IV. COMBINED WASTEWATER TREATMENT AND
RECYCLING SYSTEMS
Combined wastewater treatment and recycling systems differ from graywater recycling
systems in that-they collect and treat the total wastewater (graywater and blackwater).
The use of these systems has many significant advantages over conventional
wastewater treatment and disposal systems, both from a wastewater management
perspective as well as a water use/water conservation perspective. Reuse of on-site
wastewater saves limited and dwindling water resources and replaces or reduces the
need to develop additional sources of water supply. Although combined wastewater
treatment and recycling systems currently are not competitive with on-lot septic
tank/leach field and public sewer systems, there are many sites that are otherwise
not developable due to site conditions that could be developed with the use of such
systems.
This section presents a brief overview of combined wastewater treatment and recycling
systems, including discussion of: combined wastewater uses: basic system concepts:
currently available technologies; current and potential applications; application
considerations; installation considerations; and operation and maintenance
considerations.
COMBINED WASTEWATER USES
Of the less than 100 combined wastewater treatment and recycling systems currently
in use in commercial buildings, most recycle the treated wastewater for toilet and
urinal flushing. Other current end-uses of the treated wastewater include landscape
irrigation and supply water for ornamental ponds.
BASIC SYSTEM CONCEPTS
The major components of a combined wastewater treatment and recycling system
include collection and storage tank(s), piping, filter media, pumps(s). and controls.
Depending upon the application involved, controls are usually .more complex and, in
most cases, microprocessor-based. The treatment methods typically used include
aerobic treatment, collection, settling and sandjtttration* and biological treatment with
Jiltration and disinfection. Each is described briefly below.
Aerobic Treatment
The aerobic system uses an aerobic biological treatment process to oxidize and remove
soluble or fine suspended materials which cannot be removed simply by nitration or
sedimentation. This system provides compartmentation. hydraulic flows, and oxygen
necessary to optimize the aerobic process. No addition of chemicals usually is
required.
IV-1
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Collection, Settling and Sand Filtration
This system uses a septic tank to collect the combined wastewater from the building.
The wastewater then is pumped to the sand filter to remove suspended materials. It is
similar to the system discussed in Section 3.
Biological Treatment with Membrane Filtration. Carbon, and Disinfection
This system uses a treatment process that incorporates biological treatment.
membrane filtration, activated carbon, and ultraviolet light or ozone disinfection.
Sludge accumulates in a trash trap or in a biological treatment unit. The system
typically is housed In the basement of the building it serves or in a separate out-
building.
CURRENTLY AVAILABLE TECHNOLOGIES
Combined wastewater treatment and recycling systems are commercially available
from only a few companies, some of which also mamifacture/distribute graywater
systems. A brief discussion of four systems, including system description, application.
testing status, cost, and maintenance, is provided at the end of this section.
CURRENT AND POTENTIAL APPLICATIONS
On-site wastewater treatment and recycling system currently are being used in several
states, including California. New Jersey, New York, Maryland. Virginia. Indiana, and
Michigan. Many of these applications have been in office buildings and complexes and
schools. Other building types where such technology can be used include: shopping
centers, public recreational facilities, hotels and motels, airports, multifamily
residential facilities, industrial plants, and hospitals.
Wastewater treatment and recycling systems have been used in most applications
because the area where the building was located could not be served by a public
sewer and on-site problems prohibited a large sanitary leachfield. In other instances,
they have been used because conventional on-site treatment was a problem as a_
result of poor soil, high groundwater, wetlands, or concerns for groundwater
contamination, or water conservation was an important consideration.
APPLICATION CONSIDERATIONS
Two of the most important factors that must be considered in application of a
combined wastewater treatment and recycling system are wastewater need and
production capacity and system location. Each factor is described briefly below.
I
Wastewater Need and Production
I
For landscape irrigation, the need is established by using various rules of thumb as
discussed in Section 3. For flushing of toilets and urinals, typically 1.5 gallons (for
flush units) and 0.5 gallons per flush, respectively are used.
IV-2
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CASE IN POINT
CALIFORNIA-MOBILE HOME PARK INSTALLS WASTEWATER
TREATMENT SYSTEM FOR SURFACE IRRIGATION
A mobile home community found itself facing state mandates against discharge to
surface waters. The mobile home park owners had utilized spray irrigation following
wastewater treatment by a conventional "package" treatment plant. However, this
plant was not meeting standards due to inefficiency and peak loading problems.
A combined wastewater treatment system was installed in January 1991. The system
currently is used for treatment and the effluent is irrigated on a nearby field of non-
edible crops.
CASE IN POINT
WASTEWATER TREATMENT & RECYCLING SYSTEM
INSTALLATION AT HEADQUARTERS PARK ESTIMATED TO
SAVE $15,000 PER YEAR
A office complex near Princeton, New Jersey consists of four separate buildings
totaling 366,550 square feet of office space. It is located in a rural area where public
sewers are not available. After an initial wastewater treatment plant was rejected, a
system that reduced wastewater discharge through recycling of treated effluent for use
as flush water in the facility's toilets and urinals was chosen. This system could
reduce the wastewater discharge volume by approximately 94%. It could be easily
accommodated on-site. A capital cost savings of over $250,000, plus an estimated
water use cost savings of $ 15,000 per year, was achieved,.
W-3
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For wastewater production in a commercial building, it typically is assumed that a
building will support approximately one person for every 200 square feet of gross
space. The actual volume of wastewater to be treated is calculated based on the
number of daily uses of the toilet and urinal fixtures. It commonly is assumed that 50
percent of the occupants are men and 50 percent are women. Women use a toilet 100
percent of the tlme-and studies have shown that men use the toilet 24 percent of the
time and the urinal 76 percent of the time. The total sanitary facility use over an eight
hour period is three uses per person per day. In addition, lavatory sink use is
estimated at 0.25 gallons per toilet or urinal use. The contribution to now from
urination adds approximately 0.07 gallons per day (gpd) per fixture use.
System Location
The location of system components depends on the type of the system being utilized
Some general guidelines are:
• Installation of tanks, pumps, controls, and piping must allow easy access for
service.
• Distances from any building, lot line, or water supply must conform to local
health regulations.
* Areas (for irrigation uses) that receive runoff or are highly subject to flooding
must be avoided. ^
INSTALLATION CONSIDERATIONS
Combined wastewater treatment and recycling systems must be installed in
accordance with local plumbing codes. They usually are installed by professional.
licensed plumbing contractors who are fully familiar with the local codes and
requirements of the local health department. The installation may require
modifications of the existing plumbing system and code authorities may require a
method (e.g., labels or signs) of distinguishing potable water from wastewater.
OPERATION AND MAINTENANCE CONSIDERATIONS
One of the major objections that regulatory agencies have relative to the us of on-site
wastewater treatment and recycling systems is the reliability of operation and
maintenance. Recognizing this, many manufecturers of these systems have developed
sophisticated computerized monitoring and control systems that provide remote
monitoring and alarm capability that provides a minute by minute. 24-hour a day
surveillance on each system. They also offer (either directly or through authorized
distributors) annual service contracts to assure reliable operation of their equipment
and controls. Discussions with regulatory agencies and selected users confirms that
service contracts which provide routine preventive maintenance and inspection are a
preferred method to assure reliable operation rather than provision of periodic
emergency response. Furthermore, long term operating costs also can be more
effectively controlled when the equipment supplier/manager is made responsible for
parts and equipment replacement under a fixed management fee arrangement.
IV-4
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Cycle-Let
Thetford Corporation
P.O. Box 1285
Ann Harbor, Michigan 48106
John Irwin
800-521-3032
SYSTEM DESCRIPTION
Figure 4-1 Illustrates a typical Cycle-Let was ewater treatment and recycling system.
This system processes wastewater through a series of unit operations producing a
highly treated effluent. The treated wastewater is reused as flushwater in toilets and
urinals. Any residual effluent not reused for toilet flushing is discharged to a small
on-site subsurface disposal field or sanitary sewer. In some applications, the treated
wastewater can be used for on-site landscape irrigation.
Potable Water
Non-Potable Water
d
?
1
fZ.
\
Trash Storage
Removal
Low Volume. Highly Treated
Discharge To Sewer Or
On-Site Soil Absorption System
Figure 4-1 : Cycle-Let Wastewater Treatment and Recycling System
for Commercial and Industrial Buildings
The treatment process consists of three basic steps: biological treatment, filtration and
final polishing and disinfection. The wastewater is first collected in a buried pre-
treatment trash trap/sump tank, The trash chamber provides grit removal and gross
solids retention: the sump provides flow equalization and an emergency storage
reservoir. After treatment and equalization, the wastewater is pumped to the biological
treatment system.
IV-5
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The biological treatment system incorporates both anoxic and aerobic processes. The
first anoxic stage receives the raw wastewater. Anoxic organisms convert the nitrates
to nitrogen gas (denitrification) while consuming BOD. In the second stage, air is
supplied through blowers to provide an aerobic environment for nitrification of
ammonia, further BOD reduction, and solids digestion. The digestion process reduces
solids so efficientry-that residual stored solids are removed by hauling only once per
year.
Filtration of the biological solids is accomplished with tubular ultrafiltration
membranes. These membranes provide consistent and complete removal of suspended
solids and microorganisms. The rejected solids are returned to the Waste treatment
tank for further digestion. The filtered effluent proceeds to the final polishing step.
except for a small volume that is discharged.
Once the biological solids have bisn separated, the wastewater is polished and
disinfected. In this process the wastewater passes through activated carbon
adsorbers. This removes any remaining color and odor and produces a sparkling clear
water. Next, the flow is disinfected by ultraviolet radiation or ozone. The reclaimed
wastewater is then, stored in a treated water reservoir where it will be recycled to flush
toilets and urinals.
The process is odor free, requires no chemical additions and can be housed within the
facility it serves. Water conserving fixtures such as 1.5 gallon toilets and self-closing
lavatory faucets are generally used with the system to improve system economics.
APPLICATIONS
The Cycle-Let system is designed for hotel and motel applications and for use in
recreational facilities.
TESTING STATUS
This system has been tested and certified by NSF. It meets the requirements of NSF
Standard 41 for wastewater recycle/reuse.
SOST
The installed cost of this system varies with system size and capacity as follows.
• TW-300 (100 people served) -- $70.000
• TW-3750 (1250 people served)-- $243.000
• TW-7500 (2500 people served) -- $450.000
This equipment, however, generally is leased to the building owner.
IV-6
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MAINTENANCE
Because the system typically is leased, operation and maintenance service is provided
by Thetford Systems, Inc. Annual O&M cost range from $1000/month for the TW300
system to $5.000/month for the TW-7500 system. Cost for electricity needed for
equipment operation is borne by the building owner. Annual energy consumption for
the three systems is estimated to be as follows.
TW-300 -- 15.000 kWh/year
1W-3750 -- 70,000 kWh/year
TW-7500 -- 115.000 kWh/year
IV-7
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Cromogiass Systems
Cromoglass Corporation
P.O. Box3215
Williamsport, PA 17701
KLH Engineers, Inc.
(717) 326-3396
SYSTEM DESCRIPTION
This system operates by turbulent aeration of incoming wastes and batch treatment of
blomass in separate aeration and quiescent settling chamber (Figure 4-2). A typical
operating cycle is as follows:
Fill; Aeration
Flow enters the solids retention section which is separated by noncorrosive screen.
Inorganic solids are retained behind the screen. Organic solids are broken by
turbulence created with mixed liquor being forced through screen by submersible
aeration pumps. This eliminates the need for mechanical comminution.
Aeration
Liquid and small organic solids pass through the screen into the continuing aeration
section. Air and mixing are provided by submersible pumps with venturi aspirators
that receive air through pipe intake from the atmosphere.
Denitriflcation (Optional)
Provided by an anoxic period during the regular treatment cycle. This unit creates
anoxlc conditions by closing the air intakes of the aeration pumps with electric valves.
This stops aeration; but the system continues mixing.
Transfer/Settle
Treated mixed liquor is transferred by pumping to the clarification section. The
transfer period overfills the clarifier with the excess spilling through overflow weirs
back into the main aeration section. Transfer ceases and the clarifier is isolated -
solids separation occurs under quiescent conditions.
Discharge
After settling, effluent is pumped out of the clarifier discharge. Sludge from the bottom
of the clarifier is returned back into the main aeration section using a submersible
pump or can be wasted to a sludge processing tank.
Cromoglass Systems can be installed in modules. The system can start with one
Independent module designed to treat the initial loading. As development grows,
additional modules can be added as needed. Because a batch system requires less
land area, it can be placed in multiple locations - saving additional piping/pumping
costs.
IV-8
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D-ABUnWCHAMMM E-TTUMSFEMIVE
M-««sum.T J-AMCIXMIOX m-n-suMmupuMK s-stmwa CHAWS* o-n.oATi£VB.tooon
Figure 4-2: Cromoglass Wastewater Treatment and Recycling System
APPLICATIONS
Cromaglass Systems are designed for use in residential, commercial, and industrial
buildings.
TESTING STATUS
Cromoglass recently has initiated a performance evaluation project in conjunction
with NSF for approval using NSF Std. 41.
COST
Preliminary study indicates that this recycle capability with flows from 0 up through
12,000 GPD can be cost-effective with an individual home or similar flow system. The
installed cost of this system ranges from $7.500 to $8,500.
MAINTENANCE
Periodic maintenance is required. The manufacturer/ distributor recommends that
this be obtained through a service agreement with a local dealer.
IV-9
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Orenco System
Orenco Systems, Inc.
Roseburg, Oregon
H.L. Ball
(503) 673-0165
SYSTEM DESCRIPTION
The Orenco System (Figure 4-3) collects combined wastewater in a septic tank. A
pump or siphon housed in a screened vault within the septic tank doses the sentic
tank effluent onto the sand filter. After the effluent drains through the sand into the
bottom gravel layer, it either drains out through a 4 inch PVC pipe to the drainfield or
is dosed to the drainfleld by a pump located in a basin in the sand filter
Figure 4-3: Orenco System
IV-10
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APPLICATIONS
The Orenco System currently is being used in residential and commercial buildings.
TESTING STATUS
This system has not been tested In accordance with NSF Std. 41.
COST
The installed cost of this system ranges from $4,500 to $7,500. Equipment and
materials cost typically is 50 percent of the total initial system cost.
MAINTENANCE
Typical maintenance involves visual inspection on an annual basis, wash down of
pump walls, and sludge and scum accumulation removal on a periodic basis.
IV-11
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Clivus Multrum, Inc.
21 Canal Street
Lawrence, Massachusetts 01840-1801
Carl Lindstrom
(508)794-1700
SYSTEM DESCRIPTION
A typical combined wastewater treatment and recycling system (Figure 4-4) consists of
solid/liquid separation over a compost reactor followed by: a septic tank up-flow
anaerobic sand filter, intermittent sand filter, drip irrigation or other reuse system
Septic settling
•••anaerobic
upflouj filter*
intermittent
sand filter.
irrigation
Figure 4-4: Combined Wastewater Treatment and Recycling System
APPLICATION
This system can be used in residences primarily for sub-surface irrigation purposes.
TESTING STATUS
The system currently is being tested by the University of West Virginia. However it
has not been tested by NSF.
IV-12
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COST
The installed cost of this system is $4,700
MAINTENANCE^
The septic tank and the sand filter require maintenance on an annual basis.
IV-13
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V. BARRIERS AND CONSTRAINTS
On-site water treatment and recycling systems are being used both legally and
illegally in the U.S. To obtain an understanding of how and where these systems are
being used. and_of_the barriers and constraints that are restricting their widespread
application, a survey of NAPHCC membership was undertaken using a standardized
form (shown in Appendix C). This survey, in addition to discussions with state and
local officials, revealed a variety of barriers and constraints, including: lack of
statutory authority and regulations; restrictive and ambiguous plumbing codes: lack of
standards for recycled water, lack of confidence in standard practice for controlling
cross connections; and preference for use of reclaimed water from a central municipal
wastewater treatment plant rather than from an. on-site wastewater treatment and
recycling system. Each is described briefly below.
LACK OF STATUTORY AUTHORITY AND REGULATIONS
Many states and localities do not recognize water conservation and water-reclamation
activities. This is confirmed by a summary of state agencies dealing with
. environmental pollution control and/or wastewater discharge. As shown in Table 5-1,
only 10 states have policies, recommendations, or regulations permitting the use of
on-site graywater recycling systems, and only 8 states currently permit the use of on-
site combined wastewater treatment and recycling systems. None of the states permit
surface discharge of graywater or treated wastewater, unless discharge standards are
met.
RESTRICTIVE AND AMBIGUOUS PLUMBING CODES
Each state has a unique building regulatory system. However, model codes developed
by several key organizations (e.g.. International Conference of Building Officials.
Southern Building Code Congress International, and Building Officials and Code
Administrators International) are the basis for most state and local building codes.
The approximate areas of influences of these codes are shown in Figure 5-1. In
addition to these codes, the National Association of Plumbing-Heating-Cooling
Contractors also publishes a national plumbing code, which has been adopted in New
Jersey, North and South Dakota, and selected cities in Nebraska, Missouri.
Pennsylvania, and New Hampshire.
Although most plumbing codes (model or state) currently do not address the use of
on-site graywater recycling systems or combined wastewater treatment and recycling
systems, they do not prohibit the use of these systems. Instead, the decision regarding
their use is left up to the local code officials. The major concern that these officials
have is the possibility of cross contamination of the potable water supply. As a result.
the designer/supplier must demonstrate that the potable water supply system will not
be compromised at any time. Currently, only six counties in the state of California ~
Santa Barbara. San Luis Obispo, Mariposa, Los Angeles, San Bernardino, and San
Diego ~ have plumbing codes to permit the use of these systems. Note, however, with
it is now legal to use graywater systems in California and the Department of Water
V-l
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Table 5-1: States with Policies and Regulations on Graywater and
Combined Wastewater Treatment and Recycling Systems
Slates Gravwater
Combined
Wastewator
Systems
Contact
Alabama
Alaska
Arizona
Arkansas
California
Colorado
Connecticut
Delaware
Florida
Georgia
Hawaii
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Mksouri
Montana
Nebraska
Nevada
New Hampshire
New Jersey
New Mexico
New York
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington
West Virginia
Wisconsin
Wyoming
George Holcombe (205) 242-5007
Dick Famell (907) 465-2656
, Robert Wilson (602) 257-2270
Patrick Harris (501) 661-2171
Dave Quinton (916)445-1248
Phil Hegeman (303) 331-4564
Arthur Castellawo (203) 566-1759
Ron Graeber (302) 736-4762
David York (904) 488-4525
Bill McGiboney (404) 894-6644
Felix Udasco (808) 543-8288
Rick Mallory (208) 334-5845
Dave Antonaccia (217) 782-4977
Allen Dunn (317) 633-0100
Dairy! McAllister (515) 281-6682
Steve Page (913) 296-1343
Dave Nichols (502) 564-4856
George Robichaux (504) 568-5100
Ken Meyer (207) 289-5684
Jay Prager (410) 631-3652
Christos Dimisioris (617) 292-5912
Tom Hoogerhyde (517) 335-9214
Dave Morisetta (612) 623-5517
Ralph Tumbow (601) 960-7696
Nix Anderson (314) 751-6090
Rick Duncan (406) 444-2544
Terry Philippi (402) 471-2541
Dalo Ryan (702) 686-4750
Barry Lehneman (603) 271-3505
Bob Berg (609) 984-4429
Bob Kirkpatrick (505) 841-9450
Ralph Stewart (518) 661-2171
Tim Woody (919) 733-2895
Dave Bergsagel (701) 221-5210
Tom Grigsby (614) 466-1450
Dan Hodges (405) 271-7362
Sherman Olson (503) 229-6443
Milt Lauch (717) 787-8184
Mark Boucher (401) 227-2306
Leonard Gordon (803) 734-5096
BiO Baer (605) 773-3296
Steve Morse (615) 741-0690
Sherman Hart (512) 458-7375
Don Hanson (801) 538-6159
Ernie Christiansen (802) 879-6553
Alan Knapp (804) 786-1750
Don Alexander (804) 786-1750
Ron Forren (304) 348-2971
Dave Russell (606) 266-0056
John Harrison (307) 777-7431
V-2
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IllliSs?'
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V-3
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Resources has till July 1. 1993 to develop and adopt Installation standards for on-site
graywater systems. Further, the Chief Plumbing Inspector of Los Angeles County In
California recently has presented the Ad-hoc Graywater Committee's proposed code
changes relative to on-site graywater recycling systems to the International
Association of Plumbing & Mechanical Officials for consideration. A copy of the
proposed modifications is included in Appendix B.
Most states and localities make technical amendments when they adopt a model code
and many have provisions which allow the use of special design plumbing systems
which vary in detail from the requirements of the specific code. These provisions
typically require:
• Submission of plans, specifications and computations and other related data
for the special design.
* Installation and testing in accordance with approved criteria.
• Certification of compliance by an approved independent agency.
Although such provisions permit the use of on-site graywater recycling systems and
combined wastewater treatment and recycling systems on an experimental basis
other governing state and local regulations must also be adhered to. The process of
obtaining approvals is time-consuming and can be expensive, thus deterring the use
of such special systems.
LACK OF A NATIONAL STANDARD FOR ON-SITE RECYCLED WATER
QUALITY
The National Sanitation Foundation has established a minimum quality standard for
recycled wastewater with its certification Standard No. 41. However, it is not a
nationally accepted standard. As a result, each state and each county must establish
its own standard and develop its own regulations with regards to the use of on-site
graywater recycling and combined wastewater treatment and recycling systems The
regulatory process is generally slow to respond; therefore, the market for on-site
wastewater treatment and recycling systems currently is small and fragmented If a
uniform national standard was developed, however, there would be more acceptance
of these systems and the cost of the equipment would decline significantly. Estimates
from manufacturers indicate that cost could decline by as much as 50 percent of
current prices.
LACK OF CONFIDENCE IN STANDARD PRACTICE FOR CONTROLLING
CROSS CONNECTIONS
Although all the experience with using reclaimed water for toilet flushing has been
successful, many building and safety departments are reluctant to consider using
non-potable water in a building because of the lack of experience with procedures
used to control dual water systems.
V-4
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PREFERENCE FOR RECLAIMING WATER FROM MUNICIPAL
WASTEWATER TREATMENT PLANT RATHER THAN ON-SITE
WASTEWATER TREATMENT AND RECYCLING
The number, size, and capacity of projects involving reclaimed water from central
municipal wastewater treatment plants is growing. Today, there are 18 states (Table
5-2) that currently have regulations for reuse of reclaimed water: another 18 states
have published guidelines for reuse of reclaimed water: and 14 states do not currently
have regulations or guidelines for reuse of reclaimed water. (35)
There is a growing awareness that recycling of wastewater is an important strategy for
water conservation and peak reduction. However, public health and building officials
in many states prefer the use of reclaimed w ater from central municipal plants rather
than the use of recycled water from on-site wastewater treatment and recycling
systems. These individuals emphasize that reclaimed water has superior quality and
offers lower health risks. In addition, centralized operation permits better control over
the operation and maintenance of the system. Furthermore, reclaimed water from
central municipal plants is a major revenue source for the localities that employ it
This mind set of public health and building officials -continues to limit the widespread
use of on-site wastewater treatment and recycling systems.
V-5
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VI. ECONOMICS OF ON-SITE WASTEWATER
TREATMENT AND RECYCLING SYSTEMS
Cost is most often the determining factor in making decisions with regards to which
recycling system4s-best for the application. It also is the criteria used when deciding
between installing an on-site treatment and recycling system and purchasing
reclaimed water from a central, municipal water treatment plant.
Major cost criteria used by most homeowners and commercial/institutional building
developers and owners is initial system cost. However, many commercial and
industrial building owners that occupy their own buildings base their decisions on life
cycle cost analysis which also considers the dollar value of the benefits. Other factors
that owners consider in decision-making include wastewater reuse potential in the
building, system reliability and flexibility, ease with which plumbing modifications can
be made, and space requirements for installation of storage tanks and other
equipment.
Numerous factors should be specifically addressed when evaluating the economics of
on-site wastewater treatment and recycling system options. These include the design.
components, and the method of payment that contribute to the initial system cost:
alternative methods of acquiring the system hardware: operating and maintenance
costs, including energy, parts, and labor: interest rates: the economic life of the
system; the discount rate; and the value of tangible and intangible benefits from the
system.
ECONOMIC FACTORS
Economic evaluations should consider a variety of factors. The following discussion
identifies some of the major factors which should be considered in any life cycle cost
analysis.
t
Initial Cost
Initial cost includes the cost of design, system components, the cost of shipping these
components, the taxes involved, and the cost of installation. In existing situations, the
cost of on-site wastewater treatment and recycling system must also include any
associated modifications of the plumbing system components or layout.
The initial cost of a graywater system installed in a single-family residential or small
commercial application typically ranges from $500, for a basic "no-frills" system, to
$5,000. for a fully automated system: the cost of a on-site combined wastewater
treatment and recycling system for the same application ranges from $4,500 to
$8,500. Initial costs for on-site combined wastewater treatment and recycling systems
in larger commercial and industrial facilities typically are approximately $1.00 per
gross square foot. This includes the cost of the equipment, cost of building space, and
the cost of return on potable water supply. It also includes the cost of standby
VI-1
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sanitary sewer connection required by some systems to provide emergency service and
periodic residual solids disposal.
Estimates of initial costs should be reduced by any water conservation credits that
may be offered by water utilities. Such credits currently are not available. In the
future, however, water utilities may offer such credits to encourage water conservation
and peak reduction through use of on-site wastewater treatment and recycling
systems.
Currently, there are only two options available for the acquiring graywater and
combined wastewater treatment and recycling systems. These are: direct purchase and
leasing. Although direct purchase currently is the most commonly used method, a few
manufacturers offer lease agreements/Under a lease agreement, a lessor usually
completely finances the purchase and installation of the on-site wastewater treatment
and recycling system in a building. The lessee (building owner) makes monthly
payments to the lessor (owner of equipment) for the use of the equipment. In some
lease agreements, the owner pays for the on-site plumbing modifications, whereas the
lessor finances the initial purchase of the equipment
As on-site wastewater treatment and recycling systems become more accepted and
their use becomes more widespread, shared water savings (SWS) contracts (similar to
shared energy contracts) may become a viable option in large commercial and
industrial applications. Under a SWS arrangement, a third party designs, installs, and
owns the wastewater treatment and recycling system at the owner's facility, then the
owner and third party split the cost savings that result due to water conservation.
Operating Costs
Operating costs are related principally to energy and demand. Energy is consumed in
on-site graywater and combined wastewater treatment and recycling systems by
electric motors that operate pumps and aeration equipment and by disinfection
equipment (e.g.. ultraviolet lamps). These costs vary widely depending upon the
system being considered and, thus, should be obtained from the manufacturers. One
manufacturer (Thetford Systems. Inc.) did provide estimates of annual energy
consumption for its graywater systems for applications in hotels, motels, and -
recreational facilities. These range from 13.000 kWh (for 350 gpd system) to 95,000
kWh (for a 8.500 gpd system).
In making long-term calculations, it is important to consider the energy rates likely to
be in effect over the life of the system. Projected energy rates should be obtained from
the local electric utility.
Economic Life
The economic life of a on-site wastewater treatment and recycling system can be
determined in a variety of ways. One is to base it on the anticipated design life of the
system itself. Another is to base it on the anticipated life or remaining life of the
VI-2
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building Involved. The economic life of on-site wastewater treatment and recycling
systems considered for life cycle costs analysis typically is 20 years.
Maintenance Costs
Maintenance c6sts~also can be projected on an annualized basis. They include the
cost of replacement parts, replacement labor, filter cleaning labor, equipment repair,
and cost of maintaining control systems.
For residential and small commercial applications, the annual maintenance cost
associated with graywater systems is about $50 to $100, including the cost of filter
replacement and labor for periodic maintenance and flushing of the system. For on-
site combined wastewater treatment and recycling systems in large commercial and
industrial applications, the annual maintenance costs typically are about 2 percent of
initial equipment cost or approximately $0.15 per gross square foot.
Interest Rate
Because almost all commercial and industrial construction and modifications are
financed, the interest rate paid for borrowed funds determines the real cost of a
system and its components.
Discount Rate
The discount rate is an interest rate applied in reverse to determine the present value
of future money. One dollar received today is more valuable than one dollar received a
year from today because today's dollar can be invested in a secure, insured account. It
will have grown to more than a dollar by the end of a year. For example, if one
assumes a 6 percent interest rate can be earned with ease, then one dollar received
today will be worth $1.06 in one year.
The discount rate is applied to determine how much future money (income or
expense) is worth today. Once again, the rate applied is that rate which can be earned
easily and safely. Thus, assuming the rate is 6 percent, $1.06 received one year from
today would be worth $1.00 today:
$1.06 - {$1.00 x 0.06) = $1.00
Likewise. $1.00 received one year from today would be worth only $0.94 now.
Using this approach, one can take future expenses associated with a system, adjust
for inflation, and apply a discount rate to determine the present value of these
expenses. The present worth or present value can then be divided by the economic life
of the proposed system to develop annualized cost data in present-worth dollars.
Most texts on engineering economics provide comprehensive charts of factors that can
be used to determine the present, value of future money quickly and easily using a
number of different discount rates.
VI-3
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In retrofit applications, this approach Is frequently applied to determine whether it is
worthwhile to make an investment in water conservation. Using this approach, one
computes the future value of savings in terms of present-value dollars.
Value of Benefits
It is difficult to assign value to the benefits provided by on-site graywater and
combined wastewater treatment and recycling systems. Nonetheless, it is appropriate
to apply at least conservative approximations when they are warranted. As example.
graywater recycling in a commercial laundry facility provides an added value of
reduced energy costs. Recovered graywater is warm and heat can be recovered from
this wastewater through use of a heat exchanger to preheat domestic hot water.
Although there are initial costs associated with heat recovery, the energy cost savings
due to heat recovery can more than offset the initial cost of the equipment, resulting
in a quick payback. In addition, because recycled graywater contains nutrients ~
nitrogen, phosphorus, and potassium ~ less fertilizer may be required in many
applications involving landscape irrigation. As such, the fertilizer value of graywater
should be accounted for.
Furthermore, many commercial buildings that are likely candidates for combined
wastewater treatment and recycling systems cannot be developed without it. Many
buildings are located in areas which are not served by public sewer and on-site
problems prohibit a large sanitary leachfield. In this situation, the value of the
property becomes dependent, not on its favorable location, but on its ability to provide
sanitary facilities to employees and customers. Here, wastewater recycling adds value
to the property. It makes the difference as to whether the site can be developed at all
and. if so, what types of uses can be incorporated. In such instances, the ability to
develop the site or to simply increase the density of the development will add value far
in excess of the cost of the wastewater treatment and recycling system.
ECONOMICS OF ON-SITE WASTEWATER TREATMENT AND RECYCLING
VERSUS RECLAIMED WATER FROM A CENTRAL PLANT
The trend in water reuse is one of growth. Many cities and counties in semi-arid and
arid areas are modifying their wastewater treatment plants and distribution systems
to reclaim wastewater for landscape irrigation in public facilities like golf courses,
schools, and parks. Although little competition exists between reclaimed water from
central municipal facilities and on-site wastewater treatment and recycling systems,
this may change in the future as reclaimed water is sold by municipalities to building
owners for reuse in toilets, cooling towers, and for other purposes.
Decisions on whether reclaimed water or ori-site recycling is the most cost-effective
water reuse method should be based on life cycle cost analysis. The initial operation
and maintenance costs associated with on-site wastewater treatment and recycling
systems have already been discussed above. The initial costs associated with delivered
reclaimed water from a large scale central municipal reclamation plant include the
following costs:
VI-4
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• Biological and physical/chemical treatment
• Water storage
• Water pumping stations
• Distributipn_piping
• Operational controls
The components of the operation and maintenance costs are as follows.
• Monthly fee for reclaimed water
• Labor to operate and maintain the system
• Electricity to operate pumps and controls
• Chemicals for disinfection and coagulation
• Replacement parts for pumps, motors, etc.
In addition to the above, the cost of disruption to existing infrastructure and
community should be considered, as well as the cost to the end-user. These costs are
as follows.
• Initial connection fees
• Modifications of building plumbing system
• Cross connection protection
• Modifications to irrigation systems (if these are contemplated)
VI-5
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VII. GLOSSARY
Alarm
Biochemical oxygen
demand (BOD)
Biological Treatment
Blackwater
BOD,
Disinfection
Dosing chamber
Edible crops
Effluent limitation
Effluent
Fecal coliforms
Graywater
Landscape irrigation
An instrument or device which continuously monitors a
specific function of a. treatment process and automatically
gives warning of an unsafe or undesirable condition by
means of visual and/or audible signals.
The quantity of oxygen utilized in the biochemical
oxidation of organic matter present in water or wastewater,
reported as a five-day value established as determined
using approved methods.
Methods of wastewater treatment in which bacteria or other
living organisms treat the wastewater.
Water that is flushed from toilets and urinals that contains
human waste.
Five day biochemical oxygen demand — a standard test
indicating the quantity of oxygen utilized in five days by
wastewater under controlled temperature conditions.
The destruction of pathogens in wastewater effluents.
Tank in which premeasured chemicals are mixed with
wastewater or that stores pretreated wastewater for
periodic pressurized discharges.
Crops intended for human consumption.
Restriction on quantities, rates, or concentrations of
chemical, physical, biological, or other constituents which
are discharged to receiving waters.
Partially or completely treated wastewater discharged from
a wastewater treatment system.
Members of the coliform bacteria group capable of
producing gas from lactose at 44.5 degree C, as determined
using approved methods.
Water from washing machines, bathtubs, showers, and
bathrooms sinks.
Irrigation of lawns, trees, and shrubs on residential,
commercial and institutional properties.
VH-1
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Milligrams per liter
(mg/1)
On-site wastewatcr
system
Potable water
Reclaimed water
Reuse
Sedimentation tank
Septic Tank
SS
Subsurface irrigation
system
Total Kjeldahl
Nitrogen (TKN)
Total suspended
solids (TSS)
Treatment
The quantity of material present in water or wastewater
expressed on the basis of the weight (milligrams) per unit
volume of solution (liter).
System designed to contain, distribute, or treat
wastewater on or near the location where the wastewater is
generated.
Water that meets drinking water standards.
Effluent from a wastewater treatment facility that has been
subjected to extensive treatment in order to remove organic
material, heavy metals, and harmful pathogens (such as
bacteria, viruses, zind protozoa) to a level acceptable for
specific uses.
The deliberate application of recovered wastewater for a
beneficial purpose.
A watertight basin or tank in which liquid wastewater
containing settleable solids and suspended matter settle
out by gravity.
A watertight receptacle which receives the raw wastewater
and discharges a settled, partially treated effluent, usually
to a leach field.
Suspended solids present in wastewater.
A network of small diameter, porous or perforated
pipes installed horizontally at depth generally less than 12
inches for the purpose of releasing water at or near the root
zone of vegetation.
The sum of free ammonia and organic nitrogen compounds
in water or wastewater and expressed as elemental
nitrogen. N, as determined using approved methods.
Solids that either float on the surface or are suspended
in, water or wastewater: the quantity of material removed
from a simple in a laboratory test referred to as
nonfilterable residue, as determined using approved
methods.
Any method, technique, or process which changes the
physical, chemical, or biological character or composition of
wastewater.
VH-2
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Turbidity A condition in water or wastewater caused by the presence
of suspended matter, resulting in the scattering and
absorption of light rays, as determined using approved
methods.
Wastewater ~ The combination of liquid and water-carried pollutants
from residences, commercial buildings, industrial plants,
and institutions.
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VIII. REFERENCES
1. Olsson, Eskill, Karlgren, L.. and Tullander. V., Household Wastewater. The
National Swedish Institute for Building Research, Box 26 163,- 102 52
Stockholm 27, Sweden, 1968
2. Wallman, H. and S. Cohen. Demonstration of Waste Flow Reduction from
Households. U.S. Environmental Protection Agency Report EPA 670/2-74-071,
September. 1974.
3. Ligman, K., N. Hutzler, and W.C. Boyle. "Household Wastewater
Characterization." Journal of the Environmental Engineering Division. ASCE,
Vol. 150, No. EEI, Proc. Paper 10372, February. 1974.
4. Laak, R, Relative Pollution Strengths of Undiluted Waste materials Discharged
in Households and the Dilution Waters Used for Each. Manual of Grey Water
Treatment Practice - Part H, Monogram Industries. Inc., Santa Monica.
California. 1975.
5. Bennett, E.R and E.K. Llnstedt, Individual Home Wastewater Characterization
and Treatment. Completion Report Series No. 66, Environmental Resources
Center. Colorado State University, Fort Collins, Colorado, July, 1975.
6. Siegrist. R, M. Witt and W.C. Boyle, "Characteristics of Rural Household
Wastewater," Journal of the Environmental Engineering Division. ASCE, Vol.
102, No. EE3. Proc. Paper 12200, June, 1976.
7. Siegrist. R., Segregation and Separate Treatment of Black and Grev Household
Wastewaters to Facilitate On-Site Surface Disposal. Small Scale Management
Project, University of Wisconsin. Madison Wisconsin. 1977.
8. Karpiscak, M.M., K.E. Foster, KJ. DeCook. C.P. Gerba and R Brittain,
Summary Report on Phase n Casa del Agua: A Community Water Conservation
Demonstration and Evaluation Protect. University of Arizona. Tuscon. Arizona.
1987.
9. State-of-the-Art Assessment of Compost Toilets and Grevwater Treatment
Systems. The Wintrop Rockefeller Foundation. Little Rock, Arkansas, Feb.
1980.
10. Siegrist. R, An Evaluation of the Potential for Pathogenic Contamination of
Household Grev Water. Small Scale Waste Management Project, University of
Wisconsin. Madison, Wisconsin, February 1977.
11. Brandes. M.. Characteristics of Effluents from Gray and Black Water Septic
Tanks. JWPCF, Vol. 50. No. 11. November, 1978.
Vffl-1
-------
12. Boyle. W.C.. RR Siegrist. Chin C. Saw, Treatment of Residential Gravwater
With Intermittent Sand Filtration. Alternative Wastewater Treatment. 1982.
13. State of California. Department of Health Services, Environmental Management
Branch. Hazards Related to Gravwater. Unpublished Technical Report, 1990.
14. CCDEH Issue Paper: Gravwater Use in California. California Conference of
Directors of Environmental Health. Ventura County, CA. 1992.
15. Rose. J.B., M.M. Karpiscak, K.E. Foster. K.J. DeCook. C.P. Gerba and R
Brittain. An Experiment in Residential Water Reuse and Conservation Water
Resuse Symposium IV. American Water Works Association. August 2-7
Denver.
16. McCoy, E. and W.A. Ziebell. Effects of Effluents on Ground water-
Bacteriological Aspects. Proceedings of the National Sanitation Foundation
Conference on Individual On-Site Wastewater Systems, Ann Arbor Michigan
November. 1975. '
17« Gravwater Pilot Protect (Mid-Course Report). Office of Water Reclamation City
of Los Angeles. Califronia. June 1992. '
18. Proposed Code Change to a Section and/or Sections of the UPC-USPC-USEC
Submitted to the National Association of Plumbing and Mechanical Officials '
Los Angeles. California. February 1992.
19. Cohen. S.. and Wallman. H.. Demonstration of Waste Flow Reduction from
Households. U.S. EPA 670/2-74-071. (September. 1974). ~~
20. Hypes. W.E., Batten, C.E., and Wilkins. J.R. Processing of Combined Domestic
Bath -and -Laundry Wastewater for Reuse as Commode Flushing Water NASA
Technical Note. NASATN D-7937. (October. 1975). " '
21. University of Wisconsin. Small Sraje Waste Management Prn^t IQT-T Final
report submitted U.S.E.P.A. in fulfillment of Grant No. R802874-01.
22. Siegrist RL.. Management of Residential Grevwater. Department of Civil and
Environmental Engineering. Small Scale Waste Management Project. University
of Wisconsin. Madison. 1978.
23. Hypes. W.D., Batten. C.E., and Wilkins. J.R, The Chemical/Physical and
Microbiological Characteristics of Typical Bath and Laundry Washwaters NASA
Technical Note. NASATN D-7566 (March. 1974)
!
24. Lent, D.S.. "Treatment of Power Laundry Wastewater Utilizing Powered
Activated Carbon and Cationic Polyelectrolyte." Proceedings Purdue University
Industrial Wastewater Conference XXX. 751. (1975).
vm-2
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25. Small Scale Wastewater Management Prolect-Draft Report. Appendix A.
University of Wisconsin. Madison, Wisconsin. (1977).
26. Hoover. P.R., McNalty, K.J.. and Goldsmith. R.L.. Evaluation of Ultraffltratlon
and Disinfection for Treatment of Blackwater. U.S. Army Mobility Equipment
ResearclTaricf Development Command. Fort Belvoir. Virginia. (1977).
27. Barrows, John. "Understanding Ozone: The Most Effective Sanitizer."
Manufacturing Engineer. Del Industries. Inc.. 1992.
28. Saver. D.K., Dry Feed Chlorination of Wastewater On-Site' Small-Scale Waste
Management Project, University of Wisconsin, Madison, Wisconsin (1976).
29. Budde. P.E.. Nehm, P.. and Boyle, W.C., "Alternatives to Wastewater
Disinfection." JWPCF. 49(10): 2144-2156. (1977).
30. "Gravwater." City Department of Public Works and Building and Zoning
Division, City of Santa Barbara. California, April 1990
31. ""Guidelines for Approved Use in Residential Landscapes in the City and
County of San Luis Obispo." City and County of San Obispo, California. 1991.
32. "Residential Grevwater Treatment and Use By Subsurface Irrigation Systems."
Carlile & Associates. Inc.. San Francisco. California. 1991.
33. Whitworth. Patrick L. "Designing Grey Water Recovery Systems," Plumbing
Engineer. March 1991, pp., 18-23.
34. Karpiscak, Martin K. et al. Domestic Grevwater: A Review of Alternatives for Its
Treatment and Uses (Draft). University of Arizona, February 1992.
35. Camp, Dresser and McKee, Water Reuse Regulations and Guidelines (Draft).
Environmental Protection Agency and Agency for International Development
Washington, District of Columbia, March 1992.
36. How to Use Gravwater: Guidelines to the Approved Use of Gravwater in Santa
Barbara County. Gray Water Technical Advisory Committee. County of Santa
Barbara. California. May 1991.
vra-3
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APPENDIX A:
WORKPLAN FOR THE EVALUATION OF
THE DISTRIBUTION OF GRAYWATER THROUGH
SUBSURFACE DRIP IRRIGATION
A-l
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INTERNATIONAL ASSOCIATION OF PLUMBING
AND MECHANICAL OFFICIALS
PROPOSED CODE CHANGE TO A SECTION AND/OR SECTIONS
OF THE UPC-USPC-USEC
Note: All Code Sections that may be affected by this change must be listed;
Name Fadv Mattar. Chief Plumbing Inspector Class of Membership A
Jurisdiction/Company You Represent Los Angeles County. California Date Feb 20.1992
Mailing Address 900 S. Fremont Avenue. Third Floor
City Alhambra State CA Zip 91803
THE FOLLOWING AMENDMENT IS SUBMITTED:
Add APPENDIX W Entitled GRAYWATER SYSTEMS FOR SINGLE FAMILY
DWELLINGS
See Attached
REASON FOR CODE REVISION:
The code does not currently define graywater or set standards for the design and
construction of graywater collection and distribution systems. Since 1989, six California
counties, with more than ten million residents, have approved the use of graywater.
The California Ad-Hoc Graywater Committee was formed in May 1991 to investigate
whether graywater could be safely used. The fprmation of the Committee was prompted b;
public interest in the use of graywater as a water conservation measure, especially during
the continuing drought.
The Ad-Hoc Committee is composed of representatives of the California Conference of
Directors of Environmental Health, the California Mosquito & Vector Control Association
the California Association of Building Officials, the Building Standards Commission, the
International Association of Plumbing and Mechanical Officials, the Los Angeles Count?
Building & Safety Department, the Association of California Water Agencies, the City off
Angeles Office of Water Reclamation, the WateReuse Association of California, the Sierra
Club, the Department of Health Services, the State Water Resources Control Board, and th
Department of Water Resources.
The Committee developed this draft UPC Graywater Appendix to provide guidance (an
maximum safety) to any jurisdiction considering the legalization of graywater
installations.
Use additional sheets if necessary
Do not write below this li
CODE CHANGE
COMMITTEE'S RECOMMENDATION
No.
AIPMO-PCC-2-89 SM
10
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DRAFT
APPENDIX W GRAYWATER SYSTEMS FOR SINGLE FAMILY DWELLINGS
Section W-1 Graywater Systems. (General) t
(a) The provisions of this Appendix shall apply to the construction, alteration and repair of
graywater systems for underground landscape irrigation. Installations shall be
allowed only in single family dwellings. The system shall have no connection to any
potable water system and shall not result in any surfacing of the graywater. Except as
otherwise provided for in this Appendix, the provisions of this Code shall be applicable to
graywater installations.
(b) The type of system shall be determined on the basis of location, soil type, and
groundwater level and shall be designed to accept all graywater connected to the system
from the residential building. The system., except as otherwise approved, shall consist
of holding tank(s) which discharge into subsurface irrigation/disposal fields.
(c) No graywater system, or part thereof, shall be located on any lot other than the lot which
is the site of the building or structure which discharges the graywater; nor shall any
graywater system or part thereof be located at any point having less than the minimum
distances indicated in Table W-l.
(d) No permit for any graywater system shall be issued until a plot plan with appropriate
data satisfactory to the Administrative Authority has been submitted and approved.
When there is insufficient lot area or inappropriate soil conditions for adequate
absorption of the graywater, as determined by the Administrative Authority, no
graywater system shall be permitted.
(e) No permit shall be issued for a graywater system on any property in a geologically
sensitive area as determined by the Administrative Authority.
(f) Private sewage disposal systems existing or to be constructed on the premises shall
comply with Appendix I of this Code. In addition, appropriate clearances from the
graywater systems shall be maintained as provided in Table W-l. The capacity of the
private sewage disposal system, including required future areas, shall not be decreased
or otherwise affected by the existence or proposed installation of a graywater system
servicing the premises.
Section W-2 Definition.
Graywater is untreated household waste water which has not come into contact with
toilet waste. Graywater includes used water from bathtubs, showers, bathroom wash basins,
and water from clothes washing machines and laundry tubs. It shall not include waste water
from kitchen sinks or dishwashers.
Section W-3 Permit.
It shall be unlawful for any person to construct, install or alter, or cause to be
constructed, installed or altered any graywater system in a building or on a premises without
first obtaining a permit to do such work from the Administrative Authority.
Section W-4 Drawings and Specifications.
The Administrative Authority may require any or all of the following information to be
included with or in the plot plan before a permit is issued for a graywater system or at any
time during the construction thereof:
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DRAFT
(a) Plot plan drawn to scale completely dimensioned, showing lot lines and structures,
direction and approximate slope of surface, location of all present or proposed retaining
walls, drainage channels, water supply lines, wells, paved areas and structures on the
plot, number of bedrooms and plumbing fixtures in each structure, location of private
sewage disposal-system and 100% expansion area or building sewer connecting to public
sewer, and location of the proposed graywater system.
(b) Details of construction necessary to assure compliance with the requirements of this
Appendix together with a full description of the complete installation including
installation methods, construction and materials as required by the Administrative
Authority.
(c A log of soil formations and groundwater level as determined by test holes dug in close
proximity to any proposed irrigation area, together with a statement of water absorption
characteristics of the soil at the proposed site as determined by approved percolation
tests. Exception: the Administrative Authority may allow the use of Table W-2 in lieu of
percolation tests.
Section W-5 Inspection and Testing.
(a) Inspection
1. All applicable provisions of this Appendix and of Section 318 of this Code shall be
complied with.
2. System components shall be properly identified as to manufacturer.
3. Holding tanks shall be installed on dry, level, well-compacted soil, if underground, or
on a level, 3" concrete slab if above ground.
4. Holding tanks shall be anchored against overturning.
5. If design is predicated on soil, tests, the irrigation/disposal field shall be installed at
the same location and depth as the tested area.
6. Installation shall conform with the equipment and installation methods identified in
the approved plans.
(b) Testing
1. Holding tanks shall be filled with water to the overflow line prior to and during
inspection. All seams and joints shall be left exposed and the tank shall remain
watertight.
2. A flow test shall be performed through the system to the point of graywater
irrigation/disposal. All lines and components shall be watertight.
Section W-6 Procedure for Estimating graywater Discharge.
(a) The number of occupants of each dwelling unit shall be calculated as follows:
First Bedroom 2 occupants
Each additional bedroom 1 occupant
Cb) The estimated graywater flows for each occupant shall be calculated as follows:
Showers, bathtubs and wash basins 25 GPD/occupant.
Laundry 15 GPD/occupant.
(c) The total number of occupants shall be multiplied by the applicable estimated graywater
discharge as provided above and the type of fixtures connected to the graywater system.
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DRAFT
EXAMPLE 1.
Single Family Dwelling, 3 bedrooms with showers, bathtubs, wash basins and laundry
facilities all connected to the graywater system: ,
Total number of occupants = 2+1+1 = 4
Estimated grayw.ater flow = 4 x (25 +15) = 160 GPD
•i
EXAMPLE 2.
Singly Family Dwelling, 4 bedrooms with only the clothes washers connected to the
graywater system:
Total number of occupants = 2+1+1+1 = 5
Estimated graywater flow = 5 x 15 = 75 GPD
Section W-7 Required Area of Subsurface Irrigation/Disposal Fields. (Fig. 5)
Each valved zone shaU have a minimum effective irrigation area in square feet as
determined by Table W-2 for the type of soil found in the excavation, based upon a calculation of
estimated graywater discharge pursuant to Section W-6 of this Appendix, or the size of the
holding tank, whichever is larger. The area of the irrigation/disposal field shall be equal to the
aggregate length of the perforated pipe sections within the valved zone times the width of the
proposed irrigation/disposal field. Each proposed graywater system shall include at least
three valved zones and each zone must be in compliance with the provisions of this Section. No
excavation for an irrigation/disposal field shall extend within five (5) vertical feet of highest
known seasonal groundwater nor to a depth where graywater may contaminate the
groundwater or ocean water. The applicant shall supply evidence of groundwater depth to the
satisfaction of the Administrative Authority.
Section W-8 Determination of Maximum Absorption Capacity.
(a) Wherever practicable, irrigation/disposal field size shall be computed from Table W-2.
(b) In order to determine the absorption quantities of questionable soils other than those
listed in Table W-2, the proposed site may be subjected to percolation tests acceptable to
the Administrative Authority .
(c) When a percolation test is required, no graywater system shall be permitted if the test
shows the absorption capacity of the soil is less than 0.83 gallons per sq. ft. or more than
5.12 gallons per sq. ft. of leaching area per 24 hours.
Section W-9 Holding Tank Construction. (FIG. 1, 2, 3 & 4)
(a) Plans for all holding tanks shall be submitted to the Administrative Authority for
approval. Such plans shall show all dimensions, structural calculations, bracings and
such other pertinent data as may be required. A minimum capacity of fifty gallons is
required.
(b) Holding tanks shall be constructed of solid durable materials, not subject to excessive -
corrosion or decay and shall be watertight.
(c) Each holding tank shall be vented as required by Chapter 5 of this Code and shall have a
locking, gasketed access opening, or approved equivalent, to allow for inspection and
cleaning.
(d) Each holding tank shall have its rated capacity permanently marked on the unit. In
addition, a sign "GRAYWATER IRRIGATION SYSTEM, DANGER - UNSAFE
WATER" shall be permanently marked on the holding tank.
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DRAFT
(e) Each holding tank installed above ground shall have an emergency drain, separate
from that connecting the tank with the irrigation/disposal fields, and an overflow drain
The emergency and overflow drains shall have permanent connections to the building
drain or building 'sewer, upstream of septic tanks, if any. The overflow drain shall not
be equipped~with a shut-off valve.
(f) The overflow and emergency drain pipes shall not be less in size than the inlet pipe. Th
vent size shall be determined based on the total graywater fixture units, as outlined in
UPC Table 4-3 of this Code. Unions or equally effective fittings shall be provided for all
piping connected to the holding tank.
(g) Each holding tank shall be structurally designed to withstand all anticipated earth or
other loads. All holding tank covers shall be capable of supporting an earth load of not
less than 300 pounds per square foot when the tank is designed for underground
installation.
(h) If a holding tank is installed underground the system must be designed so that the tank
overflow will gravity drain to the existing sewer line or septic tank. The tank must be
protected against sewer line backflow by a backwater valve.
(i) Materials
1. Holding Tanks shall be steel, protected from corrosion, both externally and ,
internally, by an approved coating or by other acceptable means, shall meet
nationally recognized standards for the intended use and shall be approved by the
Administrative Authority.
2. Holding tanks constructed of alternate materials may be approved by the
Administrative Authority provided they comply with approved applicable standards.
Section W-10 Valves and Piping. (FIG. 1,2, 3 & 4)
Graywater piping discharging into the holding tank or having a direct connection to the
sanitary drain or sewer piping shall be downstream of an approved waterseal type trap(s). If
no such trap(s) exists, an approved vented running trap shall be installed upstream of the
connection to protect the building from any possible waste or sewer gasses. All graywater
piping shall be marked or shall have a continuous tape marked with the words "DANGER -
UNSAFE WATER." All valves, including the three-way valve, shall be readily accessible and
shall be approved by the Administrative Authority. A backwater valve, installed pursuant to
this code, shall be provided on all holding tank drain connections to the sanitary drain or
sewer piping.
Section W-ll Irrigation/Disposal Field Construction. (FIG. 5)
(a) Perforated sections shall be a mini-mum 3-inch diameter and shall be constructed of
perforated high density polyethylene pipe, perforated ABS pipe, perforated PVC pipe, or
other approved materials, provided that sufficient openings are available for distributioi
of the graywater into the trench, area. Material, construction and perforation of the
piping shall be in compliance with the appropriate absorption fields drainage piping
standards and shall be approved by the Administrative Authority.
(b) Filter material, clean stone, gravel, slag or similar filter material acceptable to the
Acbninistrative Authority, varying in size between 3/4" to 2 1/2" shall be placed in the
trench to the depth and grade required by this Section. Perforated section shall be laid
on the filter material in an approved manner. The perforated section shall then be
covered with filter material to the minimum depth required by this Section. The filter
material shall then be covered with untreated building paper, straw or similar porous
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DRAFT
material to prevent closure of voids with earth backfill. No earth backfill shall be placed
over the filter material cover until after inspections and acceptance.
fc) Irrigation/disposal fields shall be constructed as follows:
__ '" MINIMUM MAXIMUM
Number of drain Imes per valved zone 1
; i j
Length of each perforated line — 100 feet
Bottom width of trench 12 inches 18 inches
Spacing of lines, center to center 4 feet
Depth of earth cover of lines 10 inches
Depth of filter material cover of lines 2 inches
Depth of filter material beneath lines 3 inches
Grade of perforated lines level 3 inches/100 feet
(d) When necessary on sloping ground to prevent excessive line slopes, irrigation/disposal
lines shall be stepped. The lines between each horizontal leaching section shall be made
with approved watertight joints and installed on natural or unfilled ground.
Section W-12 Special Provisions.
(a) Other collection and distribution systems may be approved by the local Administrative
Authority as allowed by Section 201 of the UPC.
(b) Nothing contained in this Appendix shall be construed to prevent the Administrative
Authority from requiring compliance with higher requirements than those contained
herein, where such higher requirements are essential to maintain a safe and sanitary
condition.
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DRAFT
Table W-1 Location of Graywater System.
Minimum Horizontal Distance (in feet) Holding Tank Irrigation/Disposal
in Clear Required From: Field
Buildings or structures1
Property line adjoining private property
Water supply wells4
Streams and lakes4
Seepage pits or cesspools
Disposal field & 100% expansion area
Septic tank
On- site domestic water service line
Pressure public water main
5ft2
5ft
50ft
50ft
5ft
5ft
Oft
5ft
10ft
2ft3
5ft
100ft
50ft5
5ft
4ft6
5ft
5ft
10ft7
Notes: When irrigation/disposal fields are installed in sloping ground, the minimum horizontal distance
between any part of the distribution system and ground surface shall be fifteen (15) feet.
1. Including porches and steps, whether covered or uncovered, breezeways, roofed porte-cocheres, roofed
patios, car ports, covered walks, covered driveways and similar structures or appurtenances.
2. The distance may be reduced to zero feet for above ground tanks when first approved by the Administrative
Authority.
3. Assumes 45 angle from foundation
4. Where special hazards are involved, the distance required shall be increased as may be directed by the
Administrative Authority.
5. These minimum clear horizontal distances shall also apply between irrigation/disposal field and the
ocean mean higher high tide line.
6. Plus two (2) feet for each additional foot of depth in excess of one (1) foot below the bottom of the drain line.
7. For parallel construction/for crossings, approval by the Administrative Authority shall be required.
Table W-2 Design Criteria of Six Typical Soils.
Type of Soil Minimum sq. ft. of leaching/ Maximum absorption capacity
irrigation area per 100 gallons gals, per sq. ft. of leaching/
of estimated graywater discharge irrigation area for a 24-hour period.
per day.
1. Coarse sand or gravel 20 5
2. Find sand 25 4
3. Sandy loam 40 2.5
4. Sandy clay 60 1.66
5. Clay with considerable
sand or gravel 90 1.10
6. Clay with small
amount of sand or
gravel 120 0.83
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GRAYWATER SYSTEM
— Single Tank - Gravity
Vent shall be within
trap arm distance of
running trap
Screened vents
3/32" mesh
Graywater
source
1/47FT
Union or equal (TYP)
Locking Cover (access)
Approved water tight tank
VTR or 10' above grade
(support required)
Vented running trap,
if required
Fullway Valve
Irrigation System
Danger
Unsafe Water
Wye & 1/8 Bend
Backwater .V
tank above ground
l/f/FT
To building drain or sewer,
up-stream of septic tank, if any
To Irrigation system
(level or sloped)
Minimum of three irrigation
lines required for each system.
Abbreviations
C/O Cleanout
N.C. Normally Closed
VTR Vent Thru Roof
Uniform Plumbing Code
Appendix W
Figure 1
Date: 2-92
Revised
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GRAYWATER SYSTEM
—-" Single Tank - Pumped
Vent shall be within
trap arm distance of
running trap
Screened vents
3/32" or less
Graywater
source
1/47FT
Union or equal (TYP)
/
Backwater Valve
with unions
Shut-off valve
Locking Cover (access)
VTR or 10' above grade
(support required)
Vented running trap,
if required
Approved water tight tank
Grade
Imgaudn|System
Wye & 1/8 Bend
Backwater Valve
l/4"/FT
To building drain or sewer,
up-stream of septic tank, if any
Emergency
Drain (N.C.) //
3" Concrete Pad if
tank above ground
ic/o
Sewage Ejector
with Probes
Abbreviations
C/O Cleanout
N.C. Normally Closed
VTR Vent Thru Roof
To Irrigation system
Minimum of three irrigation
lines required for each system.
Uniform Plumbing Code
Appendix W
Figure 2
Date: 2-92
Revised
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GRAYWATER SYSTEM
_Multiple Tank Installation
Vent shall be within
crap arm distance of
running trap
Screened vents
3/32" mesh
Graywater
source
Capped
inlet
VTR or 10' above grade
(support required)
Union or equal (TYP)
6" above top of
highest tank
Vented running trap,
if required
Fullway Valve
Irrigation Systen
Irrigation System
r Danger >
Unsafe Water
Unsafe Water
Wye & 1/8 Bend
Backwater Valve
Emergency
Drain (N.C.)
3" Concrete Pad
Locking Cover (access)
Approved water tight
tank
1/47FT
To building drain or sewer,
up-scream of septic tank, if any
C/0
Abbreviations
C/O Cleanout
N.C. Normally Closed
VTR Vent Thru Roof
To Irrigation system
(level or sloped)
Minimum of three irrigation
lines required for each system
Uniform Plumbing Code
Appendix W
Figure 3
Date: 2-92
Revised
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GRAYWATER SYSTEM
Underground Tank - Pumped
Screened vent
3/32" mesh
Vent shall be within
trap arm distance of
running trap
Grade
•^M
Vented running trap,
if required
^M
Graywater \
source 1/4-/Fr
Union or equal (TYP)
Backwater Valve
with unions
VTR or 10' above grade
(support required)
Valve box 3.way
with cover \
Shut-off valve
1/47FT /
Overflow
C/0 (no vent)
Wye & 1/8 Bend
Backwater Valve
«-=t
1/47FT
To building drain or sewer,
up-stream of septic tank, if any
Capped emergency drain
Grade
To Irrigation system
Valve box (level or sloped)
with cover Minimum of three irrigation
lines required for each system.
Locking cover (access)
Water tight tank approved
for underground use
Sewage Ejector
pump with Probes
Graywater Irrigation System
DANGER
UNSAFE WATER
Abbreviations
C/O Cleanout
VTR Vent Thru Roof
Uniform Plumbing Code
Appendix W
Figure 4
Date: 2-92
Revised
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GRAYWATER SYSTEM
.Typical Irrigation Layout
To public
sewer
Valved Zone
Max
/SoU
Gravel
Grade
10"
3
.' * *' .•' • f» V "IV V
^::^a
•a .«* - -.--•••/•j
•••• ..• .- •:•.•:•*:
$0$
Ur
"*~bu
3" DIA (TYP)
Untreated
building paper
18" Min.
Note: each valved zone shall
have a minimum effective
absorption/irrigation area in
square feet predicated on the
estimated graywater discharge
in gallons per day-and on the
type of soil found in the area.
Area of the field shall be equal
to the aggregate length of
perforated pipe sections within
the valved zone times the
width of the proposed field.
3' perforated pipe section
Uniform Plumbing Code
Appendix W
Figure 5
Date: 2-92
Revised
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APPENDIX C:
NAPHCC GRAYWATER SURVEY
C-3
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Please Help Us...
As you might already know, NAPHCC has received a grant from the Environmental Protection
Agency
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5. Are you familiar with any manufacturers/distributors of grey water systems and/or wastewater
treatment and recycling systems? Please provide the name of each manufacturer/ distributor
name of contact and phone number. Use another page if more space is needed.
Grey Water Systems Wastewater Treatment and Recycling Systems
ManufacturenBrstributor Manufacturer/Distributor
Name of Contact Name of Contact ' • «
Phone # Phone #
6. Are you familiar with any studies that have evaluated health and safety aspects or economics of
grey water systems or wastewater treatment and recycling systems? Please provide the following
information on each study. Use another page if more space is needed.
D Yes D No
If yes, who is sponosor of study,
Sponsor/Contact/Telephone_
Sponsor/Contact/Telephone__
Sponsor/Contact/Telephone
7. Are dual plumbing systems being installed in your service territory for any of the following types of
buildings?
D single family residential buildings
D multifamily buildings
d office buildings
O other buildings or facilities (please describe)
8. What do you estimate is the average cost of installing (including plumbing modifications, equip-
ment and controls) a grey water system or a wastewater treatment and recycling system in the fol-
lowing types of buildings?
Grey Water Systems
$ single family/residential building
$ multifamily buildings
$ office buildings
Wastewater Treatment and Recycling Systems
$ single family/residential building ,t
$ multifamily buildings
S office buildings
Please return this survey to:
NAPHCC Grey Water Survey, P.O. Box 6808, Falls Church, VA 22040 or
Fax: 1 (703) 237-7442
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