Federal monitoring data has revealed where two extensively studied PFAS, or “forever chemicals,” have been found in drinking water across the U.S.
While the Environmental Protection Agency (EPA) has previously confirmed that there is essentially no safe level of exposure to chemicals PFOA and PFOS in drinking water, latest data shows over 1,700 public water systems recorded at least one PFOA or PFOS result at or above 4 parts per trillion.
The map shows public water systems where EPA monitoring recorded PFOA or PFOS at or above 4 parts per trillion, the federal Maximum Contaminant Level established for each chemical in drinking water.
The findings come from the EPA's Fifth Unregulated Contaminant Monitoring Rule, or UCMR 5, which required certain public water systems to monitor for 29 PFAS between 2023 and 2025. The final dataset was released in August.
However, an individual UCMR 5 reading at or above 4 ppt does not itself mean a water system violated federal standards, as compliance is determined using separate compliance monitoring and running annual averages.
Newsweek reached out to the EPA via email for comment.
What is PFOA And PFOS?
Both PFOA and PFOS are man-made chemicals belonging to the PFAS family. The International Agency for Research on Cancer classifies PFOA as carcinogenic to humans and PFOS as possibly carcinogenic to humans.
The chemicals have been used since the mid-20th century in a variety of industrial processes and products, including applications involving stain-, oil- and water-resistant coatings, food packaging and textiles. PFOS has also been used in firefighting foams.
As well as potential links to cancer, studies have also linked these chemicals to liver damage, thyroid disease, high cholesterol and reproductive or developmental issues.
Why Are PFOA and PFOS Still Being Found?
The presence of PFOA and PFOS in drinking-water monitoring does not mean the detections resulted from recent production. The chemicals are extremely resistant to degradation, meaning contamination from historical materials can linger long after the products were first produced.
Meanwhile, last month, the EPA quietly changed wording on its official website which previously stated that PFOA and PFOS had been phased out in the U.S.
The site previously stated: “The manufacture and import of PFOA has also been phased out in the United States.”
Non-profit the Public Employees for Environmental Responsibility (PEER) filed a complaint against this wording in October 2025, under the Information Quality Act, and in a response that came in September this year, EPA Assistant Administrator for Chemical Safety and Pollution Prevention Douglas M. Troutman wrote, “In response to PEER’s request, EPA is updating its websites.”
The page now reads: “Quantities of PFOA may be produced, imported, and used by companies.”
...
EPA Could Give Water Systems More Time
This comes as the EPA considers giving some public water systems more time to comply with federal limits for the two chemicals.
In May, the EPA announced two proposals concerning Biden-era PFAS drinking-water regulations. One would rescind regulations covering several other PFAS, while the second would retain the federal limits for PFOA and PFOS but allow eligible water systems to seek up to two additional years to comply, potentially pushing their deadline from 2029 to 2031.
Under the proposal, systems would be able to seek an exemption. EPA says exemptions provide additional time to achieve compliance and are not permission to permanently violate the drinking-water rules. The agency added that an exemption may be available where the additional time would not result in an unreasonable risk to health.
The extension has not been finalized. The EPA continues to describe it as a proposed rule after the public-comment period closed on July 20.
Contact Newsweek editors on this story: Rebecca Flood and Emma Lee-Sang