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California State Water Board Adopts Regulations Governing Use of Recycled Water for Surface Water Augmentation

After a two-year public review process, the State Water Resources Control Board (SWRCB) has adopted new regulations setting requirements for the quality of treated recycled water that may be added to surface water reservoirs providing drinking water. The SWRCB adopted the “Surface Water Augmentation Using Recycled Water” regulations in early March of this year. The public review involved two separate external review processes. According to the board, the regulations provide local water suppliers with a new means of stretching water supplies in the face of drought and future water supply uncertainties.



As SWRCB literature notes, all suppliers of domestic water to the public are subject to federal and state laws and regulations ensuring the safety of drinking water. The California Safe Drinking Water Act mandates that a public water supplier must deliver drinking water to consumers that is, at all times, pure, wholesome and potable.

In 2009, the SWRCB adopted an updated water recycling policy with the goal of significantly increasing the use of recycled water in the state. The goals included increasing recycled water use—beyond 2002 levels—by at least one million acre-feet per year by 2020, and by at least two million acre-feet per year by 2030. The SWRCB has explained that indirect potable reuse, which involves recycled water being appropriately treated and then used to supplement sources of drinking water supply, is one means of meeting the anticipated supply challenges that lie ahead due to more frequent severe droughts, climate change, and continued population growth.

In 2010, Senate Bill 918 was signed into law. It required the development and adoption of uniform water recycling criteria for surface water augmentation. Surface water augmentation is defined in the Water Code as “the planned placement of recycled water into a surface water reservoir used as a source of domestic drinking water supply.” Under Water Code § 13562, the SWRCB was required to adopt uniform water criteria for surface water augmentation by December 31, 2016.

Prior to adopting such regulations, the Water Code required the board to submit the proposed criteria to an expert panel for the panel’s review and adoption of a finding as to whether, in the panel’s expert opinion, the proposed criteria would adequately protect public health. On October 31, 2016, the panel made a finding that the SWRCB’s draft proposed regulations would adequately protect public health. The Health and Safety Code also required the scientific basis and scientific portions of the draft regulations to undergo external scientific peer review, which was completed in June of 2016.

On July 21, 2017, the SWRCB published a notice of proposed rulemaking for the surface water augmentation regulations and initiated a 53-day comment period, during which 21 written comment letters were received. A public hearing was held September 7, 2017. After reviewing the written and oral comments, SWRCB staff modified the proposed regulations. The expert panel reviewed the modifications and on November 13, 2017, made a finding that the proposed regulations, as modified, would “adequately protect public health.” After an additional comment period closed December 18, 2017, the board determined that the three comment letters received during this period did not warrant further modifications.

On March 6, 2018, the SWRCB voted unanimously in favor of a resolution adopting the proposed regulations, which added numerous new sections to Title 22 of the California Code of Regulations.


The New Regulations

The adopted regulations govern the planned placement of recycled water into a surface water reservoir that is used as a source of domestic drinking water supply. As the SWRCB explained, rather than treated recycled water being directly delivered to customers for human consumption, the treated water in the reservoir would be subject to additional treatment by a public water system’s surface water treatment plant before it could be delivered to customers for drinking.

The regulations set the requirements for the quality of treated recycled water that may be added to a surface reservoir that serves as a source of drinking water. The regulations specify the percentage of recycled water that can be added and how long it must reside there before being treated again at a surface water treatment facility and served to customers as drinking water. Minimum treatment criteria address a host of issues, such as the origin and control of raw wastewater; control of pathogenic microorganisms, regulated contaminants, and physical water quality characteristics; and monitoring of chemicals and contaminants beyond regulated contaminants and pathogenic microorganisms.

The regulations also include requirements for public notices and hearings, monitoring and reporting, and public education and outreach. The regulations are expected to streamline the permitting process for surface water augmentation projects, which is accomplished at the regional board level, according to the SWRCB.

The board’s March 6, 2018, agenda report explained that the surface water augmentation regulations would not require any public water system or recycling agency to engage in surface water augmentation. The regulations apply only to agencies that choose to engage in planned placement of recycled water into a surface water reservoir used as a source of raw water supply by a public water system.


Conclusion and Implications

Recycled water is a key component in the California Water Action Plan, which was first released by Governor Brown’s administration in January 2014 as a “roadmap” toward sustainable water management throughout the state. Interest in the use of recycled water has been growing in California as a means of enhancing local water supplies and creating drought resiliency. Adoption of the new regulations governing the use of recycled water to augment surface water supplies marks the board’s latest regulatory step in the recycled water arena. The SWRCB in 2014 established requirements for using treated recycled water to recharge groundwater. In addition, the board anticipates adopting by 2023 new regulations governing direct potable reuse, whereby treated recycled water is added directly into a drinking water system or into a raw water supply immediately upstream of a drinking water treatment plant. For more information,see:

(Steve Anderson)