California adopts rules to allow wastewater to be transformed into drinking water
A MARTÍNEZ, HOST:
California has just adopted rules that will eventually let agencies convert wastewater directly into drinking water that'll out of the tap. As KQED's Ezra David Romero reports, scientists believe the treated water could be as clean as bottled water.
EZRA DAVID ROMERO, BYLINE: Once soiled water swirls down the drain or toilet and reaches a wastewater plant, it goes through a litany of treatments.
LAKEISHA BRYANT: It is beat up a lot.
ROMERO: Lakeisha Bryant works at a wastewater purification plant in San Jose, Calif. The Santa Clara Valley Water District strains the water and forces it through tiny tubes, pipes and filters. Then it hits it with ultraviolet light.
BRYANT: Goes in and it goes out to get it where we would like it to be - also the same technology used in desalinating water.
ROMERO: Currently, the agency cleans water for things like watering grass or firefighting, but in the future they would like to purify the sewage water for human consumption. That's called direct potable reuse. This week, the California State Water Resources Control Board approved statewide guidelines for this process. Kirsten Struve is the assistant officer for Valley Water's water supply division.
KIRSTEN STRUVE: It would give us another option in our portfolio to make sure that we have water in the face of the climate crisis.
ROMERO: Her water district plans to build a demonstration facility that will cost as much as $50 million by 2025. They want to convince the public that this water is safe to drink.
STRUVE: There is a majority of people in our county who are very comfortable with potable reuse, but there's 30% who are not.
ROMERO: The new rules mean that agencies must ultra-purify the water with treatments like hydrogen peroxide and rigorously test it. Stanford University environmental engineer William Mitch has studied this water and says it's safe to drink.
WILLIAM MITCH: If you compare it side by side with what you're already happy conventional tap water, it can have comparable or even higher quality because of the extensive treatment.
ROMERO: As droughts become more frequent, UC Berkeley environmental engineer David Sedlak said the need to recycle wastewater only grows. He says Texas and Colorado have been more aggressive with water recycling because they lack alternative water sources. Arizona and New Mexico could be next.
DAVID SEDLAK: California's certainly not the first and won't be the only place in the United States where direct potable reuse is on the table.
ROMERO: California's decision doesn't mean water districts can immediately add on to their treatment plants. State agencies will need to weigh in, and districts will need to figure out what to do with the salty byproduct of the purification process. The rules could go into effect this summer, unleashing a new era of water in California.
For NPR News, I'm Ezra David Romero in San Francisco.
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