California approved its first regulations for using Direct Potable Reuse (DPR) on Dec. 18, 2023, according to the California State Water Resources Control Board (State Water Board) website. DPR is the purification of wastewater into drinking water through a treatment plant without first going through an environmental buffer, such as a groundwater aquifer, according to the California State Water Resources Control Board website.
Indirect potable reuse, in which wastewater, such as sewage water and industrial wastewater, is first transported and treated using an environmental buffer such as a groundwater aquifer before being treated at a drinking water treatment plant, is already in use in California, according to the State Water Board website. California will be the second state to allow DPR, according to the article “California Adopts Direct Potable Reuse” on the Wastewater Digest website.
The San Francisco Public Utilities Commission (SFPUC), which provides around 56% of Milpitas’ drinking water, has not started implementing facilities for DPR, SFPUC commissioner Newsha Ajami said.
“There are other agencies in the Bay Area that are considering building it, that have been building facilities to make that happen,” Ajami said. “We are talking to a few other of our utilities to collaborate on one, but that’s only a conversation.”
The Bay Area has the technology capable of doing DPR, Ajami said. It’s excellent that Milpitas will have the regulations to use that technology, Ajami added.
“From the system’s perspective it’s a little bit more complicated,” Ajami said. “I think all the utilities (will) like DPR because it gives them an opportunity to treat the wastewater and put it back in their centralized system.”
The challenge with using DPR is that it requires a lot of energy and electricity for the water to be clean, Ajami said. There is a huge carbon footprint and a huge material cost, she added.
After the treatment, “that water comes to people’s homes, and they use it for various purposes,” Ajami said. “For example, they flush it down their toilet. So the water that we use in our home for different purposes doesn’t need to be the same quality.”
Many people working at Santa Clara Valley Water are excited about the new ruling because the Silicon Valley advanced water treatment is in the Alviso area, which is in our district, Santa Clara Valley Water director for District 3 (Milpitas) Richard Santos said. They are looking forward to using recycled water for drinking water, he added.
“We’ve had three years of critical drought (2012-2016),” Santos said. “And for the last 20 years we’ve periodically had droughts (…) We continue work at the (Silicon Valley Advanced Water Purification Center) because that’s our future. And the best way of doing things is recapturing the water and cleaning it up.”
Santa Clara Valley Water has been participating in developing these new regulations for over a decade, Kirsten Struve, the Santa Clara Valley Water assistant officer for the water supply division said. Direct potable reuse is really important for improving climate resilience, she added.
“There has been years of research and collaboration with the regulators to develop rules that will be protective of public health,” Struve said. “Years to make sure that this water is reliable, and that we can have a new water supply.”
Water is too precious of a resource to only use once, Struve said. Right now, Santa Clara County receives 50% of its water from outside the county. One use of this water is to replenish the groundwater that is pumped for potable water because there is not enough rain in Santa Clara County to replenish the groundwater, Struve added.
“And with climate change, the snowpacks which currently store a lot of California’s water will be diminished,” Struve said. “And so that’s why we need to look for drought-proof and sustainable water supplies.”
Milpitas receives around 40% of its drinking water from Santa Clara Valley Water, Santos said.
“Since I’ve been elected, I’ve been to the Milpitas City Council and I encouraged them to look into getting all of Milpitas’ water from Valley Water,” Santos said. “I believe (Milpitas) has a good process (for water services) right now, but I do encourage them to look into us for even more water.”
Unfortunately, there are just too many restrictions and regulatory agencies to go through to implement DPR immediately, Santos said. He believes DPR is good for use right now, he added.
“It’s probably going to take about 10 years (to finalize the regulations),” Santos said. We are going to work with legislation, with everything we can, and we’re going to have a demonstration process that could encourage our legislators and regulatory agencies to speed up the (regulations) process.”