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Thursday, 21 December 2023 17:53

California approves rules for converting sewage waste to drinking water

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A landscaper drinks water in temperatures that have reached well above triple digits in Palm Springs, California, US, July 20, 2022. (File photo: Reuters/David Swanson) - 



LOS ANGELES: California regulators on Tuesday (Dec 19) cleared the way for widespread use of advanced filtration and treatment facilities designed to convert sewage waste into pure drinking water that can be pumped directly into systems feeding millions of household taps.

Proven technologies capable of recycling wastewater for human consumption, a concept once derided by critics as "toilet to tap", have gained greater credence in recent years as water-conscious California faces worsening drought cycles from climate change.

More than a decade in the making, the regulations adopted by the State Water Resources Control Board represent a landmark in the quest to reclaim some of the hundreds of millions of gallons of waste discharge that flows out to sea unused each year, supporters say.

"Today heralds a new era of water reuse," Patricia Sinicropi, executive director of the recycling trade group WateReuse California, said in a statement.

A number of communities have for years been blending highly purified wastewater into aquifers and reservoirs before people can drink it, a practice known in the parlance of engineers and resource managers as "indirect potable reuse".

In the sprawling Orange County suburbs south of Los Angeles, home to Disneyland and upscale beach towns, much of the drinking supply for 2.5 million people comes from highly distilled waste that is used to recharge the groundwater basin and eventually is drawn back to the surface.

The 69-page document approved on Tuesday provides a legal and regulatory framework for "direct potable reuse", allowing the end-product of advanced purification to be fed straight into drinking water systems, without first making a stop in some kind of environmental buffer.

The foundation of the technology, used for more than a decade in Orange County, puts pre-treated waste discharge through intense microfiltration, reverse osmosis and disinfection by ultraviolet light and hydrogen peroxide.

The new regulations mandate an additional ozone disinfectant process and biological carbon filtration. Greater pathogen removal and stricter monitoring is also required.


Darrin Polhemus, deputy director of the state board's drinking water division, said it would likely take at least five years before the first direct potable reuse plant is operating.


Los Angeles and San Diego also have plans to develop direct potable recycling, as does the Santa Clara Valley Water District in the San Francisco Bay area.


Texas is the only US state to have previously approved direct potable recycling, with two small-scale systems that went online in 2014 to serve towns stricken by a drought-caused water emergency. Colorado also has developed relatively limited guidelines for such projects.


The technology for purifying wastewater is similar to that used in desalination, the seemingly more palatable process of converting salt water to fresh//CNA-VOI


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