At least 70 million Americans get their water from a system where toxic PFAS “forever chemicals” were found at levels that require reporting to the Environmental Protection Agency.

That’s according to new data the EPA released in its ongoing 5-year review of water systems across the nation. The number will almost certainly grow as new reports are released every three months.

PFAS, or per- and polyfluorinated alkyl substances, are nearly indestructible chemicals widely used across industries for decades. Found in drinking water, food, firefighting foam, and nonstick and water-repellent items, PFAS resist degradation, building up in both the environment and our bodies.

Salt Lake City; Sacramento, California; Madison, Wisconsin; and Louisville, Kentucky, were among the major systems reporting PFAS contamination to the EPA in the latest data release.

Map: Where the EPA found pollutants

This map shows water systems included in the EPA’s records, as of Jan. 11. It’s based on boundaries developed by SimpleLab, a water-testing company. Click on a system to see the number of pollutants detected at or above the EPA’s minimum reporting levels and how much the most concentrated pollutant exceeded those levels. Points represent systems where the exact boundaries are not available. If you don’t see a map, click here. 

The man-made chemicals have turned up in water systems large and small, from those serving a few thousand customers to over half a million.

Of about 3,800 systems included so far, 1,245 measured at least one PFAS compound above the EPA’s reporting levels, according to USA TODAY’s analysis.

The EPA plans to collect data from thousands more systems through 2026, including many of the nation’s largest systems, such as Los Angeles, Chicago, Boston and Philadelphia.

Read our previous coverage:EPA detected “forever chemicals” in water systems serving 46 million. Is yours on our map?

What are forever chemicals?

PFAS can lead to serious health problems, including increased risk of some cancers, if people are exposed to them over a long period of time. Even at very low doses, PFAS can pose health risks.

The EPA’s minimum reporting level – the lowest concentrations reliably measured by most laboratories – for some PFAS are measured in parts per trillion. The current thresholds are near zero, replacing older limits that were higher and didn’t detect smaller concentrations of PFAS, said Shalene Thomas, a PFAS industry expert and emerging contaminants program manager at Battelle, a nonprofit research institute.

“People hear that, and they think, ‘This is really, really low. Why are we concerning ourselves with this?’” Thomas said, referring to the detection levels. “The risk to individuals and the population is based on not just what the concentration is but what the frequency of that exposure is.”

“How often are you exposed, and what’s the duration of the exposure?”

The purpose of the reporting limits, Thomas said, is to trigger water utilities to react and find treatment solutions if needed.

“Why is there a limit? It’s not like if you’re above this number, you’re going to die, and if you’re below that number, you’re going to live,” Thomas said. “It’s about population protection. It’s an action level so that utilities can react and protect you.”

Read our previous coverage:Dangerous levels of PFAS detected in water for 27 million. Did the EPA find it near you?

Is there a national drinking water standard for PFAS? 

There are no enforceable national drinking water standards in the U.S. for PFAS, but the EPA is expected to issue new regulations this year.

Last March, the EPA proposed the first-ever national drinking water standard for six PFAS. Though there are thousands of PFAS chemicals, the six compounds in the regulation had the highest manufacturing volume in the U.S. and are thought to be the most toxic, Thomas said.

If the rule is finalized and implemented, public water systems will be required to monitor for these chemicals, notify the public and reduce PFAS contamination if levels exceed the proposed standards.

Water utilities tasked with treating PFAS

Water utilities didn’t manufacture or use the chemicals, Thomas said, yet they are still tasked with cleaning them up and protecting the public.

Once the EPA’s regulation is finalized, the agency would likely use discretionary authority and focus its efforts on going after primary polluters, Thomas said.

>However, not all water utilities are equipped to install advanced and costly treatment systems to reduce PFAS from treated water. Systems vary from region to region, each with their own water sources and technical challenges that can make treatment less feasible.

Adapting to changing climate conditions is a concern for Sacramento, California, where about 80% of water supplies come from the American and Sacramento rivers. During dry years, they use groundwater, but if those wells are contaminated with PFAS, the city might not be able to rely on them, said Carlos Eliason, a spokesperson from the City of Sacramento Department of Utilities.

The city has taken several groundwater sources out of service because they contained levels of PFAS above state guidelines. Upcoming federal regulations could increase the amount of groundwater sources that need to be shut down.

Similarly, 90% of Salt Lake City’s water supply is from surface water, but groundwater wells are still important during droughts. PFAS pollution was found in two wells, one of which is important for peak summertime use, said Laura Briefer, director of Salt Lake City Department of Public Utilities.

“Water is such a priority for us in the western United States, where water is scarce,” Briefer said. “When we have challenges where contaminants can impact our ability to use water for public purposes, that is a really profound issue. We don’t have a lot of water to spare.”

More than 6,000 miles away in Guam, a U.S. island territory in Micronesia with a longtime military presence, civilians rely primarily on water produced from an aquifer in the northern half of the island. Should the aquifer become contaminated, there are no reasonable alternatives, as defined by the EPA.

Of nearly 100 water supply wells that provide water to the island, about a third had PFAS that exceeded the EPA’s proposed regulations.

The level of funding to U.S. territories to cover the cost of treatment is not enough, said Miguel Bordallo, the general manager of Guam Waterworks Authority. The authority will have to significantly raise the rates it charges its customers to finance these capital improvement projects, Bordallo said.

Guam also absorbs costs that most utilities on the U.S. mainland don’t feel, such as shipping hazardous byproducts from PFAS treatment off the island.

“It’s a huge concern, but the way we view it is that it’s the train that’s coming down the tracks and there’s no way to stop that,” Bordallo said of the imminent PFAS rule.

“Rather than trying to stop that train, we’re trying to get ahead of it.”