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Water Recycling Funding Program (WRFP)

MUNICIPAL WASTEWATER RECYCLING SURVEY

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Synopsis

The State Water Resources Control Board (Water Board), in collaboration with the Department of Water Resources (DWR), presents the final 2015 Municipal Wastewater Recycling Survey results. A total of 714,000 acre-feet1 per year (AFY) of Title 22 compliant recycled water was used for various beneficial reuses. Table 1 and Figure 1 summarize the statewide recycled water use for calendar year 2015 for each beneficial reuse.

TABLE 1: RESULTS OF THE 2015 WATER RECYCLING SURVEY (ROUNDED VALUES)

BENEFICIAL REUSE
*RW - AFY
(Rounded Values)
% Total
Golf Course Irrigation
56,000
8%
Landscape Irrigation
126,000
18%
Agriculture Irrigation
219,000
31%
Commercial
5,000
1%
Industrial
67,000
9%
Geothermal Energy Production
18,000
3%
Seawater Intrusion Barrier
54,000
8%
Groundwater Recharge
115,000
16%
Recreational Impoundment
28,000
4%
Natural Sys. Restoration, Wetlands, Wildlife Habitat
24,000
3%
Other (Sewer flushing, misc. wash-down etc.)
2,000
<<1%
2015 GRAND TOTAL
714,000
 

*One acre-foot of water is enough water to cover one acre under one foot of water, or enough water to cover a football field (including the end zones) in about 9 inches of water, and is enough to provide sufficient water for two average California families of 4 for about a year. As the survey was conducted during the California drought and water use conservation measures were in place, residential per capita water use was about 86 gallons per capita per day (R-GPCD).

Recycling municipal wastewater has become an integral part of California’s water supply, helping meet water conservation goals and providing a measure of water supply reliability. The survey identified over 714,000 AFY of Title2 22 compliant recycled municipal wastewater, an increase of approximately 45,000 acre-feet since 2009 (Table 2). The 2015 survey categorized municipal wastewater recycling into to the following beneficial uses:

Scroll over bullet points for more information.
  • Golf Course Irrigation
  • Landscape Irrigation
  • Agricultural Irrigation
  • Commercial
  • Industrial
  • Geothermal Energy Production
  • Seawater Intrusion Barrier
  • Groundwater Recharge
  • Recreational Impoundment
  • Natural Systems/Restoration
  • Other
pie chart showing municipal waste water categories

Table 2 below provides a comparison by beneficial reuse and notes the changes between the 2009 and 2015 water recycling surveys.

Table 2: Comparsion of 2009 and 2015 Statewide Water Recycling Survey Results By Benefical Reuse (Rounded to The Nearest 1,000 AFY)

BENEFICIAL REUSE
2009
2015
Change from 2009 to 2015
AFY       % of Total AFY        % of Total AFY      % Change
Golf Course Irrigation
44,000            7%
56,000           8%
12,000           27%
Landscape Irrigation
112,000          17%
126,000          18%
14,000         13%
Agriculture Irrigation
245,000          37%
220,000         31%
-25,000        -10%
Commercial
6,000           1%
4,000           1%
-2,000        -33%
Industrial
50,000           7%
67,000            9%
17,000         34%
Geothermal Energy Production
15,000            2%
18,000            3%
3,000            20%
Seawater Intrusion Barrier
49,000            7%
54,000            8%
5,000            10%
Groundwater Recharge
80,000            12%
115,000            16%
35,000         44%
Recreational Impoundment
26,000            4%
28,000            4%
2,000            8%
Natural Sys. Restoration, Wetlands, Wildlife Habitat
30,000            4%
24,000            3%
-6,000        -20%
Other
12,000            2%
2,000            <<1%
-10,000         <1%
GRAND TOTAL
  669,000

The most significant change was for groundwater recharge as indirect potable reuse with an increase of 35,000 AFY in 2015 over 2009.  Recycled water use for agricultural irrigation decreased by 25,000 AFY. During 2015 state and federal water supplies for agriculture were curtailed as a drought mitigation measure. As recycled water is used as a supplement for agricultural irrigation, reductions in the availability of state and federal water supplies resulted in a commensurate reduction in the use of recycled water. Other changes in the use of recycled water between 2009 and 2015 may be attributed to conservation efforts

Procedure

The survey was conducted by contacting water and wastewater agencies by email and direct phone calls. Responders provided their information by completing data forms through an online web portal, by phone, or by email. Information was collected about where recycled water was obtained, where it was distributed, and its uses. In cases where a recycled water system involved multiple agencies in the treatment, wholesale and retail distribution to an end user, every effort was made to avoid duplication. Additionally, in-plant process use, such as pump seals and tank washing in a wastewater treatment plant, was considered part of treatment plant operations and was not included as recycled water. Only Title 22 compliant treated municipal wastewater, originating in whole or in part from a domestic source and directly used for beneficial reuse was counted.

An important distinction made during collection of the survey data was disposal versus reuse. Every wastewater facility in the State of California disposes of its wastewater after it has been treated to the requirements established by each facility's permit. If the recycled water was used to irrigate a crop, park, or rangeland upon which cattle grazed, then it was considered to be beneficially reused and was included in the survey data. If the recycled water is put into disposal ponds that are not permitted for groundwater recharge, released into an adjacent river, or dispersed on a spray field without any crop harvest or pasturing, then the recycled water was considered to be disposed and was not included in the survey data.

This survey focused only on intentional reuse - where recycled water was delivered directly to customers for non-potable reuse, for seawater intrusion barriers, or to groundwater recharge basins for indirect potable reuse. An exception is when there is a contracted relationship between a producer and user of recycled water to use a natural watercourse as the method of conveyance to a downstream customer. There can often be post-disposal benefits resulting from release of recycled water into the environment. In some cases, agencies indicated that downstream users reused their water, or the groundwater basin was recharged by the stream or disposal ponds. Because these beneficial uses were incidental after the discharge or disposal of the effluent, they were not included in the survey, although it is acknowledged that there may be indirect benefits.

It is important to note that Title 22 of the California regulations, which contains recycled water standards and uses, identifies multiple levels of wastewater treatment and appropriate uses for each level. For each beneficial use category in the survey, all levels of Title 22 recycled water were included but not differentiated. For example, agricultural irrigation can occur with un-disinfected secondary recycled water for certain types of crops (fodder crops, non-food-bearing trees, sod farms, etc.), disinfected secondary3 (crops where the edible portion is above ground and does not contact the recycled water, pasture for animals producing milk), or tertiary level recycled water (food crops where the recycled water comes into contact with the edible portion of a food crop eaten raw). Each of these recycled water treatment levels and uses were grouped together as “agricultural irrigation.”

Results

The survey results were correlated with water recycling data submitted in the 2015 Urban Water Management Plan Update (UWMP). Correlating two independent data sources provides a high level of confidence in the completeness and accuracy of the data. The results of the survey are summarized in Tables 1 and 2 and Figure 1. Because of the complexity in how recycled water is produced and distributed in California, it was not always straightforward to list one agency for each connected system. Recycled water systems often involve more than one agency serving different roles of treatment, distribution, retail sales, or geographic service areas. For example, in many instances, a wastewater agency will produce the recycled water, but a water agency will distribute and retail the water. In other cases, a wastewater agency will produce the recycled water then provide it to a wholesaler, which in turn provides that recycled water to one or more retail agencies who distributes and sells the recycled water to its customers. Finally, in other cases, multiple agencies jointly participate in the treatment and/or distribution of recycled water. The retail agency that distributes the recycled water is generally the named agency listed in Table 3, except in the Los Angeles area4.
The distribution of recycled water use by county is shown in Table 4. As the figure indicates, almost all counties in the state are recycling water to some degree.

Previous Surveys

The first comprehensive statewide survey of recycled municipal wastewater was conducted in 1970. Major updates were conducted in 1977, 1987, and 2001, with some interim or partial revisions between the major updates. Some noted observations or trends in recycled water use over time include:

  • An increase in recycled water use in the Santa Ana, Los Angeles, and San Diego regions as a percentage of the overall state recycled use (see Figure 3).
  • An increase in the diversity of recycled water beneficial uses. Prior to the 2001 survey, agricultural irrigation accounted for over 60 percent of the recycled water use. In the 2009 survey, it was 37 percent. The overall volume of agricultural irrigation has more than doubled since 1970, but other beneficial uses have diversified and increased to a greater extent. The primary changes include increases in landscape irrigation, groundwater recharge, and seawater intrusion barriers (see Figure 4)
  • The distribution of beneficial uses of recycled water varies throughout the state. The Central Valley' primary beneficial use of recycled water is agricultural irrigation. Urban regions of the state have a greater diversity of beneficial uses with their regions.
  • An increase in complexity of recycled water interagency relationships.
  • Cooperative solutions to access and distribute recycled water to areas of higher demand.

Graphics

Interactive Report Cards

Questions or Comments?

For Survey Related Inquiries, please contact:

David Balgobin, P.E.
(916) 322-6042

For General Program Related Inquiries, please contact:

Mike Downey, P.E.
(916) 324-8404


Water Recycling Funding Program
State Water Resources Control Board
P.O. Box 944212
Sacramento, CA 94244-2120