California Adopts Regulations for Implementing Direct Potable Reuse

Further advancing the Administration’s all-of-the-above Water Supply Strategy to make California more resilient to hotter, drier conditions, the State Water Resources Control Board approved regulations that will allow water systems to develop treatment protocols to convert wastewater into high quality drinking water.

The board’s unanimous vote gives California the most advanced standards in the nation for treating wastewater to such an extent that the finished product meets or exceeds current drinking water standards. Known as direct potable reuse, the process will enable water systems throughout the state to generate a climate-resilient water source while reducing the amount of wastewater discharged to rivers and the ocean. In fact, recycling water allows water systems to add millions of gallons of additional drinking water to their supplies over time while avoiding costlier and more energy intensive water supplies.

“This is an exciting development in the state’s ongoing efforts to find innovative solutions to the challenges of extreme weather driven by climate change,” said E. Joaquin Esquivel, Chair of the State Water Board. “On top of helping us build drought-resilient water supplies, direct potable reuse offers energy savings and environmental benefits. And most importantly, these regulations ensure that the water produced is not only safe, but purer than many drinking water sources we now rely on.”

The final version of the regulations came together over many years and after an expert panel of 12 scientists and engineers evaluated work by the board’s Division of Drinking Water and determined the standards are protective of public health. Proposed regulations were released to the public in July; board staff gathered public comment and made adjustments based on that input. These revisions include added flexibility for alternative treatment techniques and clarifications about the collaboration among partner agencies on reuse projects.

Direct potable reuse relies entirely on immediate, multi-barrier treatment that can recycle wastewater to drinking water standards in a matter of hours. This contrasts with the method currently being deployed in major projects launched throughout the state, called indirect potable reuse, which further improves treated wastewater over time through groundwater recharge or dilution with surface water. While no formal direct potable reuse projects could be initiated in California until the regulations were adopted, water agencies in Santa Clara, San Diego, and the city of Los Angeles have launched pilot projects in recent years.

The newly adopted regulations comply with California’s Safe Drinking Water Act, which ensures that the water delivered by public water systems in California shall at all times be pure, wholesome, and safe to drink.

Once the new regulations are finalized through the Office of Administrative Law in 2024, water systems will be able to submit plans for direct potable use projects to the board for approval.

Source: California State Water Resources Control Board

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