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Advanced Water Treatment: From Sewage to Clean Drinking Water

August 7, 2023 | By Kali Girl

Cal Matters reports Californians may soon have the option to consume highly purified sewage water directly in their drinking water supplies, as per proposed rules presented by state water officials.

While the drought-prone state has been using recycled water for over six decades to supplement its limited water resources, existing regulations demand that it passes through a reservoir or aquifer before reaching the taps.

However, under the new state-mandated rules, wastewater will undergo rigorous treatment and monitoring before being piped to taps or mixed with raw water upstream of drinking water treatment plants.

“Toilet-to-tap” this is not. 

After the conventional primary, secondary, and tertiary treatments, sewage faces a series of rigorous steps to eliminate remaining chemicals and pathogens.

The process includes bubbling ozone, bacterial digestion, activated carbon filtration, multiple passes through reverse osmosis membranes, oxidation with hydrogen peroxide, and exposure to high-intensity UV light.

Essential minerals, like calcium, are reintroduced, and eventually, the treated wastewater undergoes standard drinking water treatment.

“Quite honestly, it’ll be the cleanest drinking water around,” said Darrin Polhemus, deputy director of the state’s Division of Drinking Water. 

“I would have no hesitation drinking this water my whole life,” said Daniel McCurry, an assistant professor of civil and environmental engineering at the University of Southern California.

“Water recycling is about finding new water, not just accepting the scarcity mindset — being more resourceful in terms of our approach,” Gov. Gavin Newsom said last May in front of Metropolitan’s Pure Water Southern California demonstration plant.

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