How recycled wastewater could help combat dwindling supplies amid CA's drought

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ByDavid Louie KGO logo
Friday, April 29, 2022
How recycled wastewater could help combat dwindling supplies
Valley Water is hoping recycled wastewater can be the future of drinking water as California's drought continues to reduce supplies.

SAN JOSE, Calif. (KGO) -- We recycle cans, bottles, paper and some plastics. Yet most of our wastewater goes down the drain where it's discharged into the bay or the ocean. California hasn't developed regulations yet to allow the use of recycled water for drinking, but the South Bay's water wholesaler and several cities see it as a critical step as a result of persistent drought and dwindling water supplies.

"As long as people are flushing, we continue to create more water. That's very important. We're hoping, we're planning on making sure that it's about 10% of our water supply in the next few years," says Valley Water Board director Tony Estremera.

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Valley Water and the City of San Jose invested $72 million to open an Advanced Water Purification Center in 2014. It takes treated wastewater and puts it through additional processes so it can be used by industrial and agricultural customers.

"We send it to microfiltration, which has a pore size 300 times smaller than the diameter of a human hair, and that small pore can remove bacteria, protozoa and large viruses and any other large particulates that are in that water," explains Valley Water Associate Engineer Zach Helsley.

Two more steps, reverse osmosis, and ultraviolet light, transform the murky wastewater into clear water.

The facility is remarkably quiet, but it is operating 24 hours a day, seven days a week, and it's producing eight million gallons of purified water per day. By law, state regulators by next year must pave the way for indirect potable reuse of purified water. The goal, is to pump it into underground reservoirs where it's mixed with groundwater and imported water for eventual use as drinking water. The City of Palo Alto is working with Valley Water for its own water purification plant.

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"We want to pump purified water all the way to our groundwater recharge basins that are located in the City of Campbell along Los Gatos Creek," says Valley Water's Kirsten Struve.

The ultimate step will be to close the loop and introduce recycled water directly into our drinking water. To help people to get over the so-called yuck factor, Valley Water gives tours of its purification plant to acquaint the public with the process. The effort appears to be helping.

A poll last year showed as many as 58 percent approve of the use of purified water, while 31 percent oppose it, and 11 percent are undecided.

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"We're blessed in Silicon Valley. People believe in science, and so we find that as long as folks understand the process, they get it," says Estremera.

It will require a change in thinking about wastewater being a resource for recycling.

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