Direct Potable Reuse is becoming a reality
These landmark regulations will go before the State Water Resources Control Board for consideration next week. If approved, they would enable projects sometimes dubbed “toilet to tap” to move forward in numerous communities, including Santa Clara County, Los Angeles and San Diego.
Reusing water “gives us a supply that in essence is always going to be there,” said Darrin Polhemus, deputy director in the division of drinking water at the water board.
Additional options for drinking water are expected to become critical as climate change intensifies the risk of drought.
Right now, most wastewater in California gets treated and then discharged into the ocean, rivers or other bodies of water. Under the proposed rules, some water could be kept within the system — treated to a higher level and, in a matter of hours or days, returned to the main water supply, in a process known as direct potable reuse.
Because of the extra treatment, “It really will be some of the highest water quality available,” said Polhemus, who has himself tasted some recycled water at a project in Southern California.
A few other Western states, including Texas and Colorado, are also experimenting with direct potable reuse. Other parts of the world, including Singapore and Namibia, have also embraced it, according to Heather Cooley, director of research at the Oakland-based Pacific Institute, a water think tank.
Coastal communities will particularly benefit from California’s proposed rules, Cooley said. That is because they typically discharge wastewater in the oceans, not rivers, and therefore do not have to worry about taking water away from fragile ecosystems or downstream users.
Plenty of water is already reused in California but is not immediately funneled back into taps after treatment.
Treated wastewater is increasingly widely used for irrigation, including in the Napa Valley, and for industrial uses.
And in a few parts of California, treated wastewater is pumped down into aquifers, where it mixes with groundwater before being pumped back up, treated again and sent to taps. That is a slower and less direct process than would be possible under the new rules the water board is considering.
The Board meeting is being held on Tuesday, December 19, 2023 at 9:00 am at:
Coastal Hearing Room – Second Floor
Joe Serna Jr. - CalEPA Building
1001 I Street, Sacramento
For those who wish to watch the video feed of the meeting, you can do so here.