Southern California has become the cradle of water recycling in the United States, with several flagship projects aiming to become the gold standard for water purification.
By Edvard Pettersson, Courthouse News Service
Can wastewater be made potable again on a mass scale? Water-district managers in California think so. At a wastewater treatment plant in Carson in the Los Angeles area, scientists and engineers have been fine-tuning their purification process since 2019.
The facility — known as the Grace F. Napolitano Pure Water Southern California Innovation Center — purifies 500,000 gallons of water each day with the goal of someday processing 300 times that amount, or 150 million gallons daily.
The project is still in the environmental planning and review phase, and for now the water is just for research — not drinking. But with construction on a permanent plant slated to begin as early as 2026, researchers here hope arid Southern California could soon be home to one of the biggest water-recycling operations in the world.
“We’re in the business of doing big projects,” Deven Upadhyay, interim general manager at the Metropolitan Water District of Southern California, said in an interview. “We saw that in the future, we could not rely on an unsustainable supply of water.”
Spurring on the project are both troubling environmental trends and new streams of federal funding. The Colorado River — the fifth-longest in the United States, as well as the water source for 40 million people and billions of dollars worth of agriculture — has faced drought conditions for more than two decades, with its reservoirs at Lake Powell and Lake Mead historically low.
Much of the American Southwest depends on the Colorado. Under a 1922 agreement, seven U.S. states and Mexico share it, with California receiving the largest allocation.
As the river continues to shrink and at the urging of the Biden administration, California, Arizona and Nevada last year reached a temporary agreement to reduce their allocations. But that agreement expires in 2026, and some experts worry withdrawals from the river are simply unsustainable. That’s prompted some Colorado River users, including Colorado itself, to get creative about water-sourcing.
In California, officials have also been looking for new sources of water for drinking and agriculture. They’ve benefited from the 2021 Bipartisan Infrastructure Law, which offers billions of dollars in new federal funding for water infrastructure projects.
The new wastewater-recycling program in Southern California fits nicely into the Biden administration’s climate-change goals. In May, officials secured almost $100 million for design and planning.
Once ready, the program will be run by the Metropolitan Water District of Southern California, which owns and operates the Colorado River Aqueduct built in the 1930s to supply the region with reliable water supplies. At the treatment plant in Carson near the Pacific coast, the agency is teaming up with Los Angeles County Sanitation Districts to recycle much of the 250 million gallons of wastewater that every day flows into the sea.
Known as the Pure Water Southern California Program, the plan envisions not only a full-scale recycling facility in Carson but also pumping stations and a 60-mile pipeline that will transport purified water inland, where it can be used to replenish underground aquifers and provide an additional supply of drinking water.
The current price tag for the first phase of the project is $6.4 billion, and financing has yet to be worked out. Still, Arizona and Nevada have already contributed to planning and research, and the Metropolitan Water District may negotiate additional investments from other Colorado River users that would also benefit from the decreased withdrawals.
A 2021 study by the Los Angeles Economic Development Corporation estimated the project would create 47,000 new jobs during construction, as well as $8.7 billion in economic activity. It would also help protect California’s water supply from earthquakes, since the San Andreas Fault runs right underneath the Colorado River Aqueduct. “This supply will not be susceptible to earthquake disruption,” Upadhyay said.
Also in Los Angeles, the LA Department of Water and Power is planning a large-scale recycling project with the city’s sanitation department, which would purify sewage treated at the gigantic Hyperion Water Reclamation Plant. Meanwhile, in San Diego, a multi-phase project aims to provide nearly half of the city’s water supply through local recycling by the end of 2035.
“California is the cradle of water recycling programs,” said Ben Glickstein, director of communications with the WateReuse Association, a trade association that advocates for water recycling programs. “These are the flagship projects.”
The purification process currently being tested by Pure Water involves three steps.
Microorganisms first remove organic material and nitrogen compounds from the water, while membranes filter out microscopic materials. The water is then put through reverse osmosis to remove bacteria, pharmaceuticals and salts. Finally, an ultraviolet light and oxidation process inactivates viruses and removes trace chemical compounds.
This three-step process is just used for water to replenish groundwater basins. Making water for direct potable use requires further purification, said Rupam Soni, community relations manager at the agency’s Carson demonstration plant.
“In California, we have the most stringent drinking water regulations,” she said. Those regulations “require much more than what is required for groundwater replenishment.”
Once reclaimed water has been purified, officials still have to convince the public to drink it. But that task could be getting easier: Partly in response to climate change and increasingly unpredictable weather patterns, there’s been a dramatic shift in recent years in general attitudes toward water recycling, said Glickstein, the WateReuse Association director.
While the science is there, experts say more can be done to help the public understand and trust water recycling.
On that front, Southern California has made strides in terms of community outreach. Demonstration plants like the one in Carson can help people accept the safety of recycled wastewater, Glickstein said.
The poster child for successful water recycling is in Orange County south of Los Angeles, where officials have pioneered the use of purified wastewater to replenish groundwater. The county now has one of the largest reuse systems in the world, processing about 130 million gallons of wastewater a day.
Most of that water is pumped to recharge basins in Anaheim, where the water naturally filters through sand and gravel before reaching underground aquifers. Some of it gets pumped into injection wells, helping to create a barrier against seawater intrusion.
It was concerns about seawater intrusion that first prompted the use of recycled wastewater back in the 1970s, said John Kennedy, the general manager of Orange County Water District. The program gradually expanded, and in 2008, the agency began using a three-step process similar to Pure Water’s to replenish groundwater.
By focusing on public outreach, Kennedy said Orange County managed to avoid public backlash against recycled wastewater. Compare that to Los Angeles and San Diego, where fears of “toilet-to-tap” water killed similar initiatives in the 1990s. “We talked to any group we could find,” Kennedy said. “That got us over the hump and the ‘toilet-to-tap’ slogan.”
These days, public trust has helped make Orange County’s water-recycling program a success. The county’s recycling facility every week welcomes visitors from all over the world, as officials from Southeast Asia, the Middle East and North Africa seek to learn about and emulate its model.
“We’re in a very good position right now,” Kennedy said. “We have one of the best water reliability systems there is.” And soon, if all goes to plan, California could have yet another.
