California moves one step closer to direct potable reuse of wastewater

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Filling up a glass with clean drinking water from kitchen faucet
The new California regulations create additional flexibility by allowing advanced purified water to be added directly into drinking water systems where it isn’t feasible to first blend it into a larger body. Photo Credit: Brian Jackson, stock.adobe.com

California’s State Water Resources Control Board has voted in favour of adopting direct potable reuse regulations that would allow municipalities to blend purified wastewater into a local drinking water supply. 

The push to utilize wastewater as a drinking source has been some 13 years in the making for the Golden State, over which time it has struggled with several extreme droughts and dwindling reservoirs. But the state board approval will still need to be accepted by California’s Office of Administrative Law, which could add up to a year before the process of building new water recycling plants becomes a reality for the state’s nearly 40 million residents. 

Regulators said wastewater treatment 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.

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Agencies in charge of direct potable reuse (DPR) 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.

“Direct potable reuse projects, when implemented, may allow public water systems access to water sources formerly discharged into the ocean as municipal wastewater, which would reduce the dependence of these water systems on other sources of water and result in more water available for uses, such as the protection and enhancement of natural resources and the environment,” states the DPR regulation.

The new California regulations create additional flexibility by allowing advanced purified water to be added directly into drinking water systems where it isn’t feasible to first blend it into a larger body.

Colorado’s Department of Public Health and Environment adopted DPR regulations last January, though no utilities have announced any actions as yet around the opportunity. Arizona, Texas and Florida also have regulations in the works.  

WateReuse California said it has collaborated with the Water Board and other stakeholders for over a decade to reach the DPR milestone. 

“WateReuse California commends the State Water Board on adopting regulations that protect public health while providing a vital new tool for California’s sustainable water future,” announced David Pedersen, general manager of the Las Virgenes Municipal Water District and president of WateReuse California, in a statement.

While California has used recycled wastewater for things such as ice hockey rink surfaces, and some crop irrigation, the ability to develop infrastructure to utilize advanced-treated wastewater as a drinking source is a first. 

After multiple reviews by independent panels of scientists, state law required the California Water Resources Control Board to approve regulations by the end of 2023.

Many studies have shown that highly-treated wastewater is essentially “purer” than standard tap water. Minerals are often stripped and then added back to the water.

In 2020, the University of Calgary’s Advancing Canadian Water Assets  program formed a partnership with Alberta’s Village Brewery to sell limited edition beer brewed with treated wastewater. 

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