How Soon Will Southern Californians Be Using Water That's Gone From Toilet To Tap?

The California State Water Resources Control Board on Tuesday approved new regulations for direct potable reuse, AKA "toilet to tap," or highly treated sewage that’s piped directly from a water treatment plant to your home.

Some of the largest direct reuse programs in the state are being developed here in Southern California.

So, when will you be able to gulp down water that’s gone from flush to faucet?

California Gov. Gavin Newsom (R) prepares to taste wastewater that was treated at the Antioch Water Treatment Plant with former Los Angeles Mayor Antonio Villaraigosa (L) and Antioch Mayor Lamar Thorpe (C) on Aug. 11, 2022 in Antioch, California.

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A bit of background

While this might sound like a new development, these regulations have been in the works for more than a decade now. And whether you realize it, there’s a decent chance you’ve already been drinking small amounts of purified sewage water in California.

Indirect potable reuse has been allowed for quite some time. That’s when sewage water is treated, pumped into a reservoir or some other environmental buffer, mixed with natural sources of water and then pumped back out and treated again.

Orange County has had one of these recycled water systems in place since 2008.

“The reality is that anyone out there on the Mississippi River, anyone out there on the Colorado River, anyone out there taking drinking water downstream from a wastewater treatment plant discharge, which I promise you you’re all doing, is already drinking toilet to tap,” said E. Joaquin Esquivel, chair of the California State Water Resources Control Board, during the meeting Tuesday.

Recycled water programs have been ongoing since the 1980s, with the finished product frequently used to irrigate places like golf courses and public parks.

Our water problems have been getting worse each year as a result of higher temperatures and extreme drought conditions exacerbated by the climate crisis. We need to explore alternatives to imported water, which is why recycling is a key part of the state’s water supply strategy.

A view of the lime post treatment section of a water treatment facility run by the Orange County Water District.

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In the near future, toilet to tap could account for as much as 10% to 15% of our supply, according to Darrin Polhemus, deputy director of the division of drinking water for the California State Water Resources Control Board.

Up to 90% of contaminated water streams can be reliably recycled, with the leftover discharge usually sent to the ocean.

The new regulations aren’t the final word on direct potable reuse. Guidance will continue to develop as systems are implemented. And there’s no requirement for localities to participate in wastewater reuse. Any projects that do go ahead should be open for public comment before they’re approved.

Is it safe?

“I would have no hesitation drinking the first glass out of the first potable reuse facility in California,” said Daniel McCurry, assistant professor of civil and environmental engineering at USC. “I think it’s going to be cleaner than most bottled water you could find.”

The new rules require a minimum of four separate treatment processes, ensuring redundancies in case one fails. And the process is monitored from beginning to end. If the water doesn’t pass the necessary requirements, it’s discarded.

A sample of purified water (L) flows next to wastewater following the microfiltration treatment process at the Groundwater Replenishment System (GWRS), the world's largest wastewater recycling plant, in the Orange County Water District.

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Reverse osmosis, UV lights and carbon filters are all part of the filtration process. Helping to pull out and eliminate everything from pharmaceuticals to PFAS, to enteric viruses and protozoa like giardia and cryptosporidium, all of which can cause serious gastrointestinal issues — 99.999999999999999999% (that’s 18 nines after the decimal point) have to be removed. That's a higher degree of purification than is required for indirect potable reuse, which has been in place.

“These are probably the most protective potable reuse regulations that’ve ever been written,” McCurry said. “There’s probably some in the industry who feel like they're too strict, but it’s probably wise for us to err on the side of caution for now.”

City of L.A.

L.A.’s recycled water program is called Operation NEXT, the goal of which is to retrofit the Hyperion wastewater treatment plant so that instead of sending our treated water out into the ocean, we can pump it back into storage systems, including the aquifer beneath the San Fernando Valley.

“It’ll create a new drinking water supply for the city of L.A. leading to sustainability and the development of local supplies. All the things that we know we need here, specifically in Los Angeles, given the climate crisis," said Jesus Gonzalez, manager of recycled water at LADWP.

Besides a retrofit to purification technologies, L.A. will also have to build pipelines all of the way from Hyperion to conveyance facilities.

Gonzalez anticipates that the $20 billion investment should supply roughly a third of the city’s future water supply. That said, it could take another 15-plus years before it’s up and running.

Los Angeles County

L.A. County is partnering with the Metropolitan Water District on a program called Pure Water Southern California, which could be the largest facility of its type in the United States, according Deven Upadhyay, executive officer at the MWD.

They’re currently in the environmental planning stage, and the cost estimate for the first phase of the program is going to be about $6 billion.

“That’s a lot of money in the water world,” Upadhyay said.

We’ll have to wait and see how the new regulations are used, but at least some of the water will be pumped into groundwater basins for storage. Upadhyay didn’t specify how much of our water could be covered by the new system.

Orange County

Orange County has the world’s largest water recycling plant, and has been running their indirect potable reuse program since 2008.

They currently produce about 130 million gallons of recycled water every day, processing all of the available wastewater across the O.C. Sanitation District.

About 40% of what’s put back into the aquifer is coming from their O.C. treatment facility.

“We’re recycling everything we can recycle in terms of taking the treated wastewater, putting it through advanced treatment to a point where it’s beyond drinking water quality, and then putting it back into the underground aquifer,” said Mehul Patel, executive director of operations for the O.C. Water District.

Patel doesn’t anticipate these new regulations will affect the current system they have in place.

However, he said there’s a possibility that O.C. could see changes as a result of the regulations south of Irvine, where they don’t have a lot of naturally occurring water storage areas, leaving them reliant on imported water. They may benefit from a direct potable reuse plant there, though nothing is planned at the moment.

San Diego

By 2035, San Diego wants recycled water to account for half of their supply. Currently, they recycle about 8% of their wastewater, sending the rest out to the Pacific Ocean.

Phase 1 of their Pure Water San Diego project is currently under construction, and is expected to be completed by 2026, providing as much as 30 million gallons of recycled water a day. That water is slated to be sent to the Miramar Reservoir, where it’ll be mixed with other water in the system.

There are no current plans for San Diego to implement direct potable reuse, according to a statement from city spokesperson Ramon Galindo. That could change with Phase 2 of the project.