Map Shows States Where Drinking Water is Contaminated With Most PFAS

The Environmental Protection Agency (EPA) has been rolling out waves of data showing which locations across the country have the highest levels of PFAS contamination in drinking water systems.

The findings, collected and put on a map by the Environmental Working Group (EWG), show that the Eastern side of the country has a significantly higher number of locations with levels of PFAS chemicals above accepted limits than the West.

The data is from the EPA’s Fifth Unregulated Contaminant Monitoring Rule, known as UCMR 5, requiring U.S. water utilities to test drinking water for 29 individual PFAS compounds.

Earlier this month, the EPA released the ninth wave of data, which showed that 7 million more Americans were drinking water contaminated with PFAS chemicals than what was found in the previous release—bringing the total to 172 million, according to EWG.

The EPA previously told Newsweek: “On April 28, 2025, the agency announced a suite of actions to address PFAS, including in water.”

The agency added: “This list is the first, not the last, of all decisions and actions EPA will be taking to address PFAS over the course of the Trump Administration.”

Why It Matters

PFAS chemicals are a group of thousands of different substances, which are classified as a Group 1 carcinogen by the International Agency for Research on Cancer.

Since the classification, research has continued to unravel their potential health risks – such as thyroid disease, liver disease, weakened immunity and many other health problems.

Despite their health risks, PFAS chemicals are highly favored in many industries for their long-lasting nature, featuring in many consumer products and even smartwatch wristbands.

Given their widespread use, experts have said that data continuing to reveal the chemicals’ presence in drinking water is not all that surprising.

What To Know

The EWG’s map highlights which locations have concentrations of different PFAS chemicals above the EPA’s maximum contaminant level for individual chemicals in the group.

While the EPA has not explicitly established a broader PFAS maximum contaminant level—meaning the maximum concentration allowed in drinking water supplies—it has maximum accepted levels for a number of PFAS chemicals.

The chemicals PFOA, PFOS, PFHxS and PFNA all have listed maximum contaminant levels: for PFOA and PFOS, it is 4 parts per trillion (ppt), and for PFHxS and PFNA, its 10 ppt.

In all the locations on the EWG’s map that are colored light blue, traces of at least one of these contaminants were at levels higher than accepted by the EPA.

Those colored dark blue had concentrations of these chemicals below the accepted amount. Purple colors signify military bases, while orange signifies “other known sites.”

In total, there are 3,309 sites that have reported having PFAS in drinking water supplies through the EPA’s UCMR 5 data collection as of August 2025.

However, it is important to note that the data shows the locations’ highest levels of different PFAS chemicals, meaning these levels are subject to change and do not indicate whether a water system has since changed sources or is treating the water to reduce PFAS levels.

Additionally, EWG noted that “all locations represented on the map are approximate and intended to portray the general area of a contamination site or a community water system.”

Under EPA rules, water utilities have until 2027 to complete initial monitoring of PFAS chemicals, and by 2029, all public water systems must have implemented solutions to reduce the PFAS chemicals to below maximum contaminant levels.

What People Are Saying

The EPA previously told Newsweek: “PFAS are widely used chemicals that break down very slowly over time and can be prevalent in the environment, including being found in sources of drinking water. This is a key reason why EPA has been monitoring for PFAS in drinking water. EPA is committed to addressing PFAS at its source and is evaluating tools to reduce discharges and limit the impacts on ratepayers from treatment costs that would be imposed on drinking water and wastewater systems.”

Jennifer Freeman, a professor of toxicology at Purdue University, Indiana, previously told Newsweek: “It is very important PFAS drinking water testing continues so we can attain a fuller understanding of where the contamination is occurring and where treatment methods may be needed to reduce exposures.”

She said: “It is likely already impacting health outcomes across the country with these exposures likely occurring over the past several decades. On the positive side, as drinking water testing continues we now have a better understanding of the PFAS presence in our drinking water supplies and are identifying the regions where contamination is higher and action is needed.”

Vasilis Vasiliou, chair and professor of environmental health sciences at Yale School of Public Health, previously told Newsweek: “Chronic exposure to PFAS, even at low levels, has been linked in multiple studies to serious health outcomes, including certain cancers, immune dysfunction, thyroid disease, liver toxicity, and developmental effects. The sheer scale of potential exposure means this could become a major public health challenge in the years ahead. Addressing PFAS contamination is not just an environmental issue, it is a public health imperative.”

He said: “As monitoring expands, I expect even more communities will be identified, since PFAS are extremely persistent and widespread. What we need now is stronger regulation, expanded monitoring, investment in water treatment, and a rapid phase-out of non-essential PFAS uses.”