How a California County Eliminated PFAS From the Water Supply

Yorba Linda, Calif., is home to the largest water treatment plant in the country using ion exchange to remove PFAS from its water supply. The plant has been in operation since 2021, and it's been extremely effective — there is no trace of these “forever chemicals” in the water going out to the plant’s 80,000 customers.

PFAS, or per- and polyfluoroalkyl substances, are everywhere — in the soil, water, food, household materials and the blood of more than 98 percent of the population. Accumulation in the body has been associated with adverse health effects ranging from certain cancers to liver damage, thyroid disease and miscarriage.

The Environmental Protection Agency (EPA) estimates that 158 million people are exposed to PFAS via their drinking water supply. The Biden administration introduced landmark water quality standards last year that set limits on PFAS levels in drinking water and required states to comply by 2029. It’s not yet clear how the Trump administration will change these standards — this week, EPA Administrator Lee Zeldin announced that the agency would extend the deadline for compliance with the new standard to 2031. The EPA will also eventually revise the limits, Zeldin said in a congressional hearing Wednesday.

A detailed account of PFAS treatment facilities in other water districts isn’t readily available, but a 2024 survey by the American Water Works Association found that just 17 states had approved a PFAS treatment system design for ground and/or surface water. The EPA has estimated that as many as 10 percent of the 66,000 water systems in the country will need to address PFAS.

Yorba Linda, then, is ahead of the game. The water district started worrying about addressing PFAS years before federal rules required it. When construction of the plant began in 2020, PFAS concentrations in some wells were two or three times higher than the level at which the state water board advised districts not to serve water. “We had a PFAS problem that we had to address,” says Mark Toy, the district’s general manager.

Inside the plant, 22 tanks stand quietly in two rows across the back of a parking lot, connected by pipes and valves. They are cream-colored and clean, decorated with American flags and logos for the city and county water districts. There are no jarring industrial sounds, no whirring parts, no smoke or steam. The plant doesn’t have the feel of infrastructure so complex and intimidating that it would be out of reach for a typical water district.

All 10 wells from which the water district draws its supply are close enough to the property for it to be treated at the same facility. Water drawn from the wells passes through vats in which positively charged resin beads act as magnets to attract negatively charged PFAS compounds. They remain stuck to the beads as the water moves on toward taps and showerheads.

Todd Colvin, Yorba Linda’s chief water systems operator, would like to see residents get past misconceptions about drinking tap water. “It’s better than the bottled water you buy,” he says. “We are doing great things.”

City-County Partnership

Human-made PFAS chemicals, of which there are thousands, have been used in consumer products since the 1940s. They are valued for their resistance to heat, oil and water, but the chemical properties that make them useful also make them slow to degrade. Their potential to persist for thousands of years earned them the nickname “forever chemicals.”

The EPA’s 2024 rules reflected a determination that it wasn’t safe for two common PFAS chemicals, PFOA and PFOS, to be in drinking water at any level. (PFOA has been used in the manufacture of food packaging, water-resistant clothing and non-stick cookware; PFOS in stain-resistant coating and firefighting foams. Even though both have been phased out globally, they persist in the environment.)

The presence of PFAS in drinking water is a concern at the level of parts per trillion (ppt). One part per trillion is the equivalent of a single drop of water in 20 Olympic swimming pools, Toy says.

Orange County is blessed with a large groundwater basin, sustained by the world’s biggest wastewater recycling and groundwater recharge system. The basin holds enough water to meet 85 percent of the demand from local districts. By 2019, it was apparent that PFAS posed a long-term threat to the safety of this essential resource. The board of directors of the Orange County Water District (OCWD) adopted an aggressive PFAS treatment policy.

As part of this policy, it committed to paying for the design and construction of treatment facilities and to oversee delivery of them. Wells found to be contaminated have been taken offline while treatment plants are built, with imported water used as necessary to fill the gap.

The Yorba Linda plant was completed in 2021, after just 18 months of construction. It’s the biggest of its kind in Orange County, but it’s not the only one. Treatment plants have been put in place in every jurisdiction where PFAS have been detected in source water. These include the cities of Fullerton, Anaheim, Garden Grove, the City of Orange and Tustin. Some have more than one, located in proximity to impacted wells.

Water districts in these cities share the cost of plant operations with the county and pay it for the water they draw from the aquifer. The economics are stable, not endangered by shifting federal priorities.

Polluters May Pay

Customers have had to bear a 10 percent annual rate increase to pay for the PFAS program, says Jason Dadakis, executive director of water quality and technical resources for OCWD. This isn’t meant to be a long-term solution, however. It’s beginning to have success with state and federal grants, and secured a low-interest loan from the EPA a couple of years back.

OCWD is also hoping to recover money from PFAS manufacturers through lawsuit settlements. “We're hopeful that some of these supplementary sources can help pay for some of these projects, so that our local ratepayers can get some rate relief,” Dadakis says.

In the meantime, every customer in Orange County is receiving water free of PFAS.