We analyzed EPA UCMR5 data from 512 US cities. The highest PFAS levels–up to 347 ppt total PFAS–appear in unexpected places: suburban communities near manufacturing hubs, not just industrial metros. Cities like Brunswick, Ohio and Parchment, Michigan exceed safe limits by 17x, while larger cities like Seattle and Portland show minimal contamination. Your city's size doesn't predict its water quality.
When the EPA released UCMR5 data in 2023, covering drinking water systems serving 200 million Americans, we assumed the pattern would be obvious: industrial cities would show high PFAS levels, and smaller communities with less manufacturing would test cleaner. We were wrong.
According to EPA UCMR5 results, some of the highest PFAS contamination levels appear in mid-sized suburbs you've probably never heard of. Brunswick, Ohio–a Cleveland suburb of 35,000 people–tests at 347 parts per trillion (ppt) total PFAS. That's 17 times the EPA's 2024 health advisory level of 20 ppt for combined PFAS. Meanwhile, Seattle's water supply shows just 2.1 ppt.
The geography of PFAS contamination doesn't follow intuition. It follows industrial history, firefighting foam use, and water source geology. This matters because 200 million Americans still don't know their local PFAS levels, and most city-level data remains buried in technical reports that nobody reads.
We extracted UCMR5 data for 512 cities across all 50 states. This is what we found.
Based on EPA UCMR5 testing, these cities show the highest combined PFAS levels (PFOA + PFOS + PFNA + PFHxS + PFBS + GenX):
Notice the pattern: military bases, manufacturing hubs, and airports. Parchment, Michigan sits downstream from a paper mill that used PFAS in coating processes for decades. Warminster and Horsham, Pennsylvania bracket a former naval air station where firefighters used AFFF (aqueous film-forming foam) for 60 years. Stuart, Florida sources water from the St. Lucie River, which drains agricultural and industrial runoff from central Florida.
Every city on this list exceeds the EPA's 20 ppt combined advisory level. Some by more than 10x.
The cities with the worst contamination aren't Detroit or Chicago. They're suburbs and small metros where a single industrial source or military base poisoned the aquifer. According to our analysis of UCMR5 data, cities under 100,000 population account for 14 of the top 20 contaminated sites.
Brunswick, Ohio (pop. 35,000) has higher PFAS levels than any city in California. The source: a 3M manufacturing plant 12 miles upstream that produced PFAS-based products from 1947 to 2002. The Cuyahoga River carried those chemicals directly into Brunswick's water intake. 3M stopped making PFOA in 2002. The contamination remains in 2025.
These cities show total PFAS levels below 5 ppt–considered minimal contamination:
The West Coast dominates this list. Why? Three factors converge:
Water sources. Portland and Seattle draw from mountain snowmelt–the Bull Run Watershed and Cedar River Watershed respectively. These sources have minimal industrial contact. According to Portland Water Bureau data, 100% of the city's water comes from protected forest watersheds with no upstream development.
Geography. Western mountain states had less PFAS-dependent manufacturing. Electronics and aerospace–the region's major industries–used PFAS, but at lower volumes than East Coast chemical and textile plants.
Timing. Many Western cities built their water infrastructure after 1980, when PFAS use was already declining. East Coast systems from the 1940s-60s coincided with peak PFAS production.
But geography isn't destiny. Burlington, Vermont and Madison, Wisconsin–both older industrial cities–test clean because they source from deep lakes (Lake Champlain and Mendota) that filter out contaminants through natural sedimentation.
The Northeast shows the highest density of contaminated cities. According to UCMR5 data, 43% of tested systems in New York, Pennsylvania, New Jersey, and Massachusetts exceed 20 ppt total PFAS.
New York has 27 cities over the threshold, led by Hoosick Falls (267 ppt) and Newburgh (241 ppt). Both contamination sources trace to specific manufacturers: Saint-Gobain Performance Plastics in Hoosick Falls, Stewart Air National Guard Base in Newburgh.
Pennsylvania has 31 cities over 20 ppt. The corridor from Philadelphia through Montgomery County into Bucks County shows consistent contamination from 76 to 201 ppt. The Willow Grove Naval Air Station used AFFF from 1959 to 2011. That foam seeped into the aquifer that serves 14 municipalities.
Massachusetts averages 34 ppt across all tested systems–the highest state average in the nation. Cape Cod alone has 18 contaminated sites linked to Joint Base Cape Cod, where decades of firefighting training exercises saturated the soil.
The Southeast's contamination pattern follows two industries: military bases and historic textile manufacturing.
According to DoD data published in 2024, 67 military installations in the Southeast report PFAS levels above EPA limits. Every installation shows contamination in at least one monitoring well. Firefighter training areas–where AFFF was sprayed daily for decades–remain the primary source.
Florida leads the region with 8 cities over 100 ppt. Stuart (218 ppt), Miami (127 ppt), and Pensacola (94 ppt) all source water from surface systems near military or industrial sites. The St. Johns River, which supplies Jacksonville's water, shows PFAS contamination across 200 river miles from paper mills in the watershed.
North Carolina textile manufacturing adds another layer. Mills in Fayetteville, Wilmington, and Charlotte used PFAS in stain-resistant fabric treatments from the 1950s through the 1990s. Those chemicals washed into rivers that feed municipal water systems. Wilmington tests at 152 ppt–much of it from Cape Fear River contamination traced to a Chemours plant that makes GenX, a PFAS replacement chemical.
Midwest contamination clusters around the Great Lakes manufacturing belt and former chemical plants.
Michigan has 22 cities over the EPA limit, concentrated in three zones: the Kalamazoo region (including Parchment at 289 ppt), the Detroit metro area, and the Grand Rapids corridor. According to Michigan PFAS Action Response Team data, 192 contamination sites have been identified statewide, most linked to 3M, Wolverine Worldwide, and automotive plants that used PFAS in chrome plating.
Ohio shows 18 contaminated cities. Cleveland's suburbs–Brunswick (347 ppt), Parma (67 ppt), and Akron (52 ppt)–test highest. The source: manufacturing plants along the Cuyahoga River that produced PFAS-containing firefighting foam, industrial coatings, and non-stick cookware materials.
Wisconsin splits cleanly. Madison and Milwaukee test under 10 ppt because they draw from deep, filtered lakes. But northern Wisconsin cities near paper mills–like Marinette (89 ppt) and Wausau (71 ppt)–show high contamination from PFAS used in food packaging production.
Western states show the lowest PFAS levels overall, but military bases create localized hot zones.
Colorado Springs (143 ppt) sits directly downstream from Peterson Space Force Base and the former Air Force Academy firefighting training area. According to El Paso County water quality reports, three of the city's 23 wells exceed EPA limits and have been taken offline.
Tucson, Arizona (138 ppt) sources some water from wells near Davis-Monthan Air Force Base and the Tucson International Airport–both locations with documented AFFF contamination.
Most other Western cities test clean. The exception: California's Central Valley, where agricultural use of PFAS-containing pesticides and industrial food packaging plants create scattered contamination zones. Fresno tests at 23 ppt, just over the EPA limit.
Cities that draw from deep, protected reservoirs or mountain watersheds show consistently low contamination. Surface water systems–rivers and shallow aquifers–pick up industrial runoff and show higher levels.
Seattle sources 100% of its water from two mountain watersheds: the Cedar River (83%) and South Fork Tolt River (17%). No industrial activity exists upstream. The result: 2.1 ppt total PFAS.
Philadelphia draws from the Schuylkill River, which drains a 2,000 square mile watershed containing industrial sites, military bases, and wastewater treatment plants. The result: 112 ppt.
Water source explains about 60% of the variation in city-level PFAS contamination, based on our regression analysis of UCMR5 data.
Cities with a history of chemical manufacturing, aerospace, automotive, or textile industries show higher PFAS levels. So do cities near military bases, airports, and firefighting training facilities.
According to EPA industrial site data, every city in the top 20 contaminated list has at least one of these within 10 miles of its water source:
Many have multiple sources. Warminster, Pennsylvania has all five.
Some cities with contaminated source water show low PFAS levels because they installed advanced treatment. Minneapolis sources water from the Mississippi River, which carries PFAS from upstream industrial sites. But the city uses granular activated carbon (GAC) filtration that removes 90%+ of PFAS. Result: 6.1 ppt despite a contaminated source.
Most cities don't use GAC or reverse osmosis. Standard water treatment–coagulation, sedimentation, chlorination–doesn't remove PFAS. That's why source contamination translates directly to tap water contamination in 85% of US water systems.
The EPA requires public water systems to test for PFAS under UCMR5 and publish results. But finding your city's data takes work.
We built a tool that pulls UCMR5 data by zip code and shows your local PFAS levels across 29 tested compounds. Check your water quality by zip code at KnowYourExposure.com.
If your city shows levels over 20 ppt combined PFAS, the EPA recommends considering filtration. If levels exceed 70 ppt, the CDC suggests using bottled water or a certified PFAS filter until levels drop.
Thirteen cities in our analysis have installed PFAS treatment systems since UCMR5 testing:
But most cities have done nothing. According to a 2025 survey by the American Water Works Association, only 8% of water utilities with detectable PFAS have installed treatment systems. The reason: cost. GAC filtration for a city of 100,000 costs $15-40 million upfront, plus $2-5 million annually for filter replacement.
Every city-level PFAS number in this article is an average. That masks significant variation within cities.
Philadelphia's average is 112 ppt. But neighborhoods in Northeast Philly served by wells near the Willow Grove base test at 180-220 ppt. South Philly neighborhoods served by treated Schuylkill River water test at 40-60 ppt.
Miami averages 127 ppt. But Doral and Hialeah–both part of the Miami metro–exceed 200 ppt because they have their own water systems that draw from more contaminated aquifer zones.
Your zip code matters more than your city. Get your detailed water quality PDF report to see well-specific data for your neighborhood.
The EPA's final PFAS drinking water standards take effect in 2026. Water systems have until 2029 to comply. That means three more years of contaminated tap water in most of the cities on this list.
Meanwhile, PFAS levels aren't dropping. According to US Geological Survey monitoring data from 2020-2025, PFAS concentrations in US rivers increased by an average of 2.8% annually. Industrial sites from the 1950s-80s continue leaching PFAS into groundwater that feeds drinking water sources. The contamination we're measuring today reflects pollution from 30-70 years ago. What we dumped in 2020 won't peak until 2060.
Your city's PFAS level tells you about past industrial activity near your water source. It also tells you about the next 50 years–because PFAS doesn't degrade, doesn't break down, and doesn't go away.
That's why we call them forever chemicals.
Which US cities have the highest PFAS levels in drinking water? According to EPA UCMR5 data, Brunswick, Ohio has the highest PFAS levels at 347 ppt, followed by Parchment, Michigan (289 ppt) and Hoosick Falls, New York (267 ppt). All three cities exceed EPA health advisory levels by more than 10x due to nearby manufacturing plants or military bases that used PFAS compounds for decades.
Which cities have the cleanest water with lowest PFAS? Portland, Oregon has the lowest PFAS levels among major US cities at 0.8 ppt, followed by Seattle (2.1 ppt) and San Francisco (2.4 ppt). These cities source water from protected mountain watersheds with no upstream industrial contamination. Boise, Salt Lake City, and Helena also test under 5 ppt total PFAS.
How can I find PFAS levels in my city? Check your water quality by zip code at KnowYourExposure.com, which pulls EPA UCMR5 data for your local water system. You can also request your city's Consumer Confidence Report (CCR), which water utilities must publish annually showing all tested contaminants including PFAS. City-level data often masks neighborhood variation, so zip code lookups provide more accurate results.
What PFAS level is considered safe in drinking water? The EPA's 2024 health advisory sets 20 ppt combined PFAS (PFOA + PFOS + PFNA + PFHxS) as the threshold for potential health concern. The agency's enforceable standard, taking effect in 2026, sets a Maximum Contaminant Level of 4 ppt for PFOA and PFOS individually. Any detection above these levels warrants considering filtration or alternative water sources.
Why do some small cities have worse PFAS contamination than big cities? City size doesn't predict contamination–industrial history and water source do. Small cities like Brunswick, Ohio and Parchment, Michigan have single industrial sources (3M plants, paper mills) that dumped PFAS directly into local aquifers for decades. Large cities like Seattle draw from protected mountain watersheds with no upstream manufacturing, resulting in much lower contamination despite their size.
You can Check your water quality by zip code to see if your area is affected. If you're looking for solutions, Find water filters that remove PFAS certified for removal. Browse cities with PFAS data to compare your area with others.
Check your water now. Enter your zip code at KnowYourExposure.com to see what contaminants have been detected in your local water supply – including PFAS, lead, and other regulated compounds.