PFAS contamination has been detected in drinking water systems across all 50 states. An estimated 165 million Americans are drinking tap water contaminated with these synthetic chemicals, sometimes called “forever chemicals” because they don’t break down naturally in the environment. The real question isn’t which states have PFAS, but where the contamination is most concentrated and what levels are actually in your water.
Why PFAS Is Everywhere, Not Just Some States
Early mapping efforts made it seem like PFAS was a regional problem, clustered around a few industrial hot spots. That picture was incomplete. As testing has expanded, detectable levels of PFAS have turned up in water systems in every state, from rural communities in the Midwest to major metro areas on both coasts. The contamination comes from multiple sources: manufacturing plants that used PFAS in production, airports and military bases where PFAS-containing firefighting foam was used for decades, wastewater treatment plants that can’t filter out these chemicals, and even landfills where consumer products leach PFAS into groundwater.
The U.S. Department of Defense alone has identified 723 military installations, former bases, and National Guard facilities that required assessment for PFAS contamination as of March 2025. At 55 of those sites, the chemicals were found in nearby drinking water at levels high enough to trigger immediate action. These bases are spread across the country, which partly explains why PFAS contamination doesn’t respect state lines.
States With the Highest Known Contamination
While all states are affected, some have significantly more documented contamination sites. States with dense industrial histories, large military footprints, or aggressive testing programs consistently top the list. Michigan, New Jersey, California, North Carolina, and New York have some of the highest numbers of known contamination sites, partly because they’ve tested more aggressively than other states. Michigan alone has hundreds of documented PFAS sites tied to manufacturing and military activity.
Other heavily affected states include Pennsylvania, where water systems near former industrial sites have recorded elevated PFAS levels, and states with major Air Force or Navy installations like Colorado, New Mexico, and Florida. In many cases, communities near these bases relied on wells that drew from the same groundwater plumes contaminated by decades of firefighting foam use.
States that appear to have less contamination may simply have done less testing. Before the EPA’s 2024 federal rule, there was no national requirement for water systems to test for PFAS, so detection depended on whether a state chose to look. Some states with minimal reported contamination may have significant, undiscovered problems in smaller water systems and private wells that have never been sampled.
The New Federal Standard for PFAS
In April 2024, the EPA finalized the first-ever national limits on PFAS in drinking water. The rule sets maximum contaminant levels for five individual PFAS compounds. The two most studied, PFOA and PFOS, are each capped at 4 parts per trillion. Three additional compounds (PFHxS, PFNA, and HFPO-DA) are each limited to 10 parts per trillion. These are extraordinarily low thresholds. Four parts per trillion is roughly equivalent to four drops of water in an Olympic-sized swimming pool.
Water systems now have to test for these chemicals and reduce levels that exceed the limits. This means that over the next several years, communities that never tested before will begin reporting results, and the national picture of contamination will become much clearer. Some states, including New Jersey, Michigan, Vermont, and Massachusetts, had already adopted their own PFAS limits before the federal rule, in some cases stricter than the EPA’s numbers.
How to Check Your Water
Your water utility is required to publish annual water quality reports, sometimes called Consumer Confidence Reports. If your system has already tested for PFAS, the results should appear there. You can also search the EPA’s PFAS monitoring data online by entering your zip code or water system name. If you’re on a private well, no one is required to test your water for you. You’d need to send a sample to a certified lab, which typically costs between $200 and $400.
Keep in mind that “detected” doesn’t automatically mean “dangerous.” Many water systems have trace levels of PFAS that fall below the new federal limits. What matters is whether the concentrations exceed 4 parts per trillion for PFOA or PFOS, or 10 parts per trillion for the other regulated compounds.
Filtering PFAS at Home
If your water contains PFAS above the federal limits, or if you simply want an extra layer of protection, home water filters can significantly reduce these chemicals. Three technologies are effective: granular activated carbon filters, ion exchange resin filters, and reverse osmosis systems. Each works differently. Activated carbon traps PFAS molecules in tiny pores as water flows through. Ion exchange resins use charged beads to attract and hold the contaminants. Reverse osmosis forces water through a membrane thin enough to block PFAS.
When shopping for a filter, look for certification under NSF/ANSI Standard 53 (for carbon and resin filters) or NSF/ANSI Standard 58 (for reverse osmosis systems). These certifications confirm that the filter has been independently tested to reduce PFAS. One important caveat: as of mid-2024, the certification testing standards haven’t yet been updated to match the EPA’s new, very low limits. A certified filter will meaningfully reduce PFAS in your water, but it may not bring levels all the way down to 4 parts per trillion. The EPA is working with testing organizations to close that gap.
Simple pitcher filters using activated carbon can help with PFAS, though under-sink reverse osmosis systems are the most thorough option. Standard refrigerator filters and basic faucet attachments vary widely in effectiveness, so checking for the specific NSF/ANSI certification matters more than the brand name.
Blood Levels Are Dropping, Slowly
The CDC has tracked PFAS levels in Americans’ blood since 1999 through its national health survey. Between 1999 and 2019, blood concentrations of PFOS dropped by more than 85%, and PFOA levels fell by more than 70%. These declines reflect the phaseout of certain PFAS from consumer products and industrial processes that began in the early 2000s. But PFAS as a broader chemical class includes thousands of compounds, and newer versions have replaced the ones being phased out. The chemicals already in the environment, in groundwater, in soil, in landfills, will persist for decades or longer, which is exactly why they earned the “forever chemicals” label.