After more than a decade in the making, California’s efforts to create a regulatory framework for transforming recycled wastewater into safe, reliable purified water will take effect on October 1, following recent approval of Direct Potable Reuse Regulations by the state’s Office of Administrative Law (OAL).
California’s State Water Resources Control Board voted in December 2023 to adopt direct potable reuse regulations that establish criteria for the introduction of recycled water either directly into a public water system or into a raw water supply immediately upstream of a water treatment plant.
“WateReuse California has collaborated with the Water Board and countless stakeholders for over a decade to reach this important moment. This is a critical component of the Governor’s Water Supply Strategy,” announced David Pedersen, president of WateReuse California, in a statement.
Pure Water Southern California is currently under development as one of the largest recycled water facilities in the world, which could serve some 19 million service area residents once the facility is up and running by 2032.
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“Pursuing direct potable reuse for a portion of the supplies produced at our Pure Water facility will allow us to better manage the weather extremes we face from a changing climate. This is a critical new resource, and these regulations make public health the top priority,” announced Deven Upadhyay, interim GM of the Metropolitan Water District of Southern California and VP of the WateReuse Association.
Regulators said California’s wastewater treatment for direct potable reuse will consist of “no less than four separate treatment processes” for each of the following pathogens: enteric viruses, Giardia lamblia cyst, and Cryptosporidium oocyst. Treatment mechanisms will also have to include one membrane physical separation mechanism, one chemical inactivation mechanism, and one UV inactivation mechanism, according to the regulations. Other processes include a reverse osmosis membrane process and an advanced oxidation process.
Agencies in charge of direct potable reuse will also need to establish a total organic carbon chemical control point and a control point monitoring location that provides representative sampling of the advanced treated water prior to distribution.
