Water recycling — once dubbed “toilet-to-tap” by naysayers — has officially entered a new era in California.
This month, statewide regulations for what’s technically called “direct potable reuse” went into effect. The rules allow wastewater — yes, the water that goes down the drain or is flushed down the toilet — to be treated to drinkable standards then distributed directly to homes and businesses.
Mickey Chaudhuri, treatment and water quality manager for the Metropolitan Water District of Southern California (MWD), said the new rules are “a gamechanger.”
“It's a groundbreaking moment for California,” Chaudhuri said. “The regulations are a model for other states and other countries.”
Chaudhuri said the rules allow the MWD and other water agencies to have a lot more flexibility and resilience in the face of increasingly severe swings between dry and wet years driven primarily by global fossil fuel pollution.
“Regardless of wet or dry, you've got a source of supply through recycled water,” Chaudhuri said. “You’re able to better manage the weather extremes.”
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Maybe you remember the concept of the water cycle from elementary school: When water from lakes, rivers and the ocean evaporates, it condenses to form clouds, then falls back to the earth in the form of rain or snow.
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But as our climate heats up, water on the landscape, such as mountain snow and rain-fed streams and lakes, evaporates more quickly and dries out soils faster. That leaves less water for humans and the animals and plants that rely on that surface water, and also leads to a “thirstier” atmosphere, which then dumps that evaporated water in the form of increasingly intense storms and atmospheric rivers.
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That’s why the climate crisis is making California’s drought-to-deluge cycle even more extreme.
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Learn more about how this increasingly extreme weather “whiplash” affects our water supply.
The background
For decades, Southern California water suppliers have led the state in using recycled water to irrigate parks, medians and golf courses. When it comes to drinking recycled water, Orange County Water District has done that for more than 15 years, and was a pioneer in advancing methods for safely recycling water for drinking across the world. (Read our coverage about it here).
Previously, California law only allowed “indirect potable reuse,” which is what the Fountain Valley facility does — highly treated wastewater is injected underground into an aquifer, where further, natural filtration occurs. Then that water is put into the pipelines to our homes and businesses.
Direct potable reuse, which is what these newly effective regulations are about, skips that step where the water is injected into groundwater basins. Instead, the highly treated sewage water goes directly to drinking water treatment plants and then is distributed.
Why it matters
The climate crisis is driving longer and more extreme droughts, pushing our already overstretched water supplies to the brink. By 2040, California is projected to lose 10% of its traditional water supply — that’s more water than the state’s largest reservoir, Lake Shasta, can hold at capacity.
Recycling more water for drinking is one way Southland cities are working to lessen reliance on imported water from reservoirs fed by the overstretched Colorado River and less reliable snowpack in the Sierra Nevada.
But not every city has storage space to put recycled water in groundwater basins, or their reservoirs are far from wastewater treatment facilities so it wouldn’t be cost-effective to recycle more water.
Because these new regulations allow recycled water to be put directly into the local water system, more cities can recycle water for drinking that don’t happen to have an underground basin, or don’t have enough space in groundwater basins because of past pollution, which is the case for cities such as L.A. and Santa Monica.
“If you have direct potable reuse, you can bypass all of that, send it straight to the drinking water plant and straight to the customers,” said Sunny Wang, water manager for Santa Monica.
He said the city, which now has one of the most advanced and unique water recycling facilities in the world that recycles both stormwater and wastewater (and it’s all under the parking lot of the Civic Center) is likely to implement direct potable reuse as soon as 2027.
As for the Metropolitan Water District (MWD) — the agency is currently partnering with L.A. County Sanitation Districts to build what will be one of the largest water recycling systems in the world and play a large role in the agency's efforts to ease reliance on the Colorado River.
Currently, some 250 million gallons of L.A. County's wastewater is treated to a non-drinkable, but still clean level, then released into the ocean a few miles off the coast. The project aims to recycle all of it to drinkable standards through this new project.
And the new rules will provide flexibility for how the agency manages water supply during increasingly severe swings between wet and dry years.
“This allows you to capture that water, harness it, treat it, and make the best beneficial use of that water,” Chaudhuri said.
He said about two-thirds of the water will be recycled through indirect potable reuse, and as much as one-third via direct potable reuse.
By the mid-2030s, when the project is expected to be online, in wet years, MWD’s some 19 million customers may drink more recycled water so that more water from the Colorado River or Sierra Nevada snowpack can be stored for dry years, while in dry years, that recycled water will help boost groundwater basins and provide a reliable drinking water supply, Chaudhuri said.
Is it safe?
The health regulations for this type of water recycling are the most stringent in the nation – even more stringent than the rules for indirect potable reuse.
“People have to get over mentally where the water is coming from,” said Wang. “People think, why don't we do more stormwater? But there's actually more contamination in stormwater once it hits the street…heavy metals, oil and grease. If you look at PFAS/PFOS there's orders of magnitude more PFAS in our stormwater urban runoff than there is in our wastewater.”
“We actually have to use wastewater to dilute stormwater so it's easier to treat,” Wang said. “So really, wastewater is a much easier source to treat because a lot of the contaminants are organic in nature.”
The direct potable reuse process also requires additional treatment steps beyond what’s used in indirect potable reuse (learn how that works here), such as biological activated carbon, said Chaudhuri.
What’s it mean for bills?
It likely means a rate increase, though not always, and the level of increase depends on the details of the water system of each water agency. The upfront costs for building the necessary infrastructure are high across the board.
MWD’s water recycling facility, which will recycle as much as 150 million gallons of water per day, is expected to cost some $6 billion. Santa Monica's new facility, which recycles about one million gallons per day, cost $96 million.
Still, recycled water is a lot cheaper than desalinated ocean water, and it's about on par with imported water once the pipes are flowing, said Chaudhuri. And as traditional imported supplies dwindle, aging infrastructure to transport that water needs more maintenance, and new infrastructure is needed to maximize that water supply, the price of imported water is only increasing, he noted.
When the necessary infrastructure is complete, direct potable reuse can actually be more cost-effective for many cities, said Wang. That’s because it’s expensive to install underground wells for indirect potable reuse, and there’s not much space for them in highly urban areas.
“The reason why we're looking hard at direct potable reuse is it's hard to find space for a groundwater recharge well,” Wang said. “If you look at a city like Santa Monica, we're fully built out. It's a combination of where can we put this injection well, does that location allow us to capture water back, and is it a space that we could acquire property to do this?”
Plus, with ongoing remediation of contaminated groundwater basins, which L.A. is dealing with as well, there’s a further lack of storage space there for recycled water.
Santa Monica has already mostly built the needed infrastructure to comply with the new regulations, supported in large part by state and federal grants, and they’re currently assessing how rates may be affected if they do go the direct potable reuse route.
“We're 200 feet of pipeline and a pump station away from connecting it all up,” said Wang.
The MWD is also assessing how rates will be affected before determining the timeline of their large water recycling project, which could be complete by the mid-to-late 2030s, depending on what timeline they go with.
But rate hikes can never cover the cost of such projects alone, and it’s essential not to overburden ratepayers, Wang said. He said more federal and state funding, such as Proposition 4 on the upcoming November ballot, will be important for large and small water agencies alike to expand water recycling.
“I think smaller agencies are excited about it, but the worry is the upfront investment,” Wang said.
