Next phase of recycled water begins in California

Achieving a major milestone in the state’s efforts to maximize the potential of recycled water, the State Water Resources Control Board recently announced proposed regulations that would allow for water systems to add wastewater that has been treated to levels meeting or exceeding all drinking water standards to their potable supplies. The process, known as direct potable reuse, will enable systems to generate a climate-resilient water source while reducing the amount of wastewater they release to rivers and the ocean.

This development advances California Governor Gavin Newsom’s all-of-the-above Water Supply Strategy, which includes the goal of recycling and reusing at least 800,000 acre-feet of water per year by 2030.

This turning point in California’s history with recycled water, which began in the mid-20thcentury with the use of recycled water for crops, comes after an expert panel of 12 scientists and engineers evaluated work by the State Water Board’s Division of Drinking Water and determined that the proposed regulations are protective of public health. The regulations are the most advanced in the nation and reinforce California’s position as a leader of innovative solutions to climate challenges. They are now open for public comment and subject to revision based on that input.

“This moment has been some time in the making because we have been careful and thorough to produce regulations that ensure, down to a chemical level, that water treated to these standards will be pure and wholesome,” said Darrin Polhemus, deputy director for the Division of Drinking Water. “In fact, the extensive treatment requirements we’ve proposed mean that direct potable reuse processes in California will produce water of higher quality and lower risk than many traditional drinking water sources.”

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 to 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 can be initiated in California until the regulations are adopted, water agencies in Santa Clara, San Diego and the city of Los Angeles have launched pilot projects in recent years.

“We’ve seen real enthusiasm and interest from major urban water agencies, who are the ones that will take direct potable reuse forward, adding it to their water supply portfolios to increase resiliency,” added Polhemus. “California has been a leader for years in water recycling, and this last step–going directly from treatment to usage as drinking water–builds on that experience and the expertise of scientists and engineers who have worked with recycled water for many years.”

The board will consider adoption of the regulations before the end of the year.

About the State Water Board
The State Water Board’s mission is to preserve, enhance and restore the quality of California’s water resources and drinking water for the protection of the environment, public health, and all beneficial uses, and to ensure proper resource allocation and efficient use for present and future generations.