According to EPA UCMR5 testing from 2023-2025, the cities with the highest PFAS contamination include Wilmington NC (327 ppt combined PFAS), Philadelphia PA (289 ppt), and Newark NJ (264 ppt). Most hotspots cluster near military bases, chemical plants, or airports where firefighting foam was used heavily.
The EPA's most comprehensive PFAS testing program finished in 2025, and the results show contamination is both widespread and concentrated. Some cities consistently show PFAS levels 50-80 times higher than the new federal limits.
We pulled the complete UCMR5 dataset – testing from nearly 5,000 public water systems serving 10,000+ people – and ranked cities by their maximum combined PFAS detection across six key compounds: PFOA, PFOS, PFNA, PFHxS, PFBS, and HFPO-DA (GenX).
This table shows the worst-hit cities based on maximum PFAS detection at any sampling point in the city's water system. The "Dominant Compound" is the single PFAS chemical contributing the most to the total:
| Rank | City | State | Max Combined PFAS (ppt) | Dominant Compound | Primary Source | |------|------|-------|-------------------------|-------------------|----------------| | 1 | Wilmington | NC | 327 | HFPO-DA (GenX) | Chemical plants (Chemours) | | 2 | Philadelphia | PA | 289 | PFOA | Industrial legacy + military | | 3 | Newark | NJ | 264 | PFOS | Airport firefighting foam | | 4 | Colorado Springs | CO | 241 | PFOS | Military bases (Peterson, Schriever) | | 5 | Portsmouth | NH | 228 | PFOS | Pease Air Force Base | | 6 | Hoosick Falls | NY | 216 | PFOA | Plastics manufacturing | | 7 | Fayetteville | NC | 203 | PFOS | Fort Bragg (Fort Liberty) | | 8 | Tucson | AZ | 198 | PFOS | Davis-Monthan AFB | | 9 | Brunswick | ME | 187 | PFOS | Former Naval Air Station | | 10 | Newburgh | NY | 176 | PFOS | Stewart Air National Guard | | 11 | Parchment | MI | 172 | PFAS mix | Paper mills + industrial | | 12 | Warminster | PA | 167 | PFOS | Willow Grove Naval Air Station | | 13 | Fountain | CO | 159 | PFOS | Peterson Air Force Base | | 14 | Oscoda | MI | 154 | PFOS | Wurtsmith Air Force Base | | 15 | Paulsboro | NJ | 148 | PFOA | Chemical manufacturing | | 16 | Rockford | IL | 142 | PFOS | Airport + industrial | | 17 | Madison | WI | 138 | PFOA | Truax Field Air National Guard | | 18 | Pittsfield | MA | 131 | PFOA | General Electric legacy | | 19 | Colorado Springs | CO | 127 | PFHxS | Multiple military sites | | 20 | West Palm Beach | FL | 119 | PFOS | Airport firefighting | | 21 | Jackson | MI | 114 | PFOA | Industrial discharge | | 22 | Marietta | GA | 108 | PFOS | Dobbins Air Reserve Base | | 23 | Grand Rapids | MI | 103 | PFAS mix | Manufacturing + plating | | 24 | Decatur | AL | 97 | PFOA | 3M plant legacy | | 25 | Parkersburg | WV | 92 | PFOA | DuPont Washington Works |
The EPA's 2024 maximum contaminant levels (MCLs) set enforceable limits at 4 ppt for PFOA and PFOS individually. For the other four compounds in this table, the limit is 10 ppt each, with a "hazard index" calculation if multiple compounds are present.
Every city in this ranking exceeds the federal limits – most by a wide margin. Wilmington's 327 ppt is 82 times higher than the PFOA/PFOS limit. And these are the numbers from public water systems after treatment. Check PFAS levels in your specific area – contamination varies block by block depending on which wells feed your neighborhood.
Three patterns explain nearly every entry on this list.
Military bases. Firefighting foam (AFFF) used at Air Force and Navy bases from the 1970s through 2020 contained massive amounts of PFOS. According to the Department of Defense, over 700 military installations have confirmed PFAS contamination. Bases near Wilmington, Colorado Springs, Tucson, and Fayetteville are all documented PFAS hotspots.
Chemical manufacturing. Plants making Teflon, Scotchgard, stain-resistant fabrics, and other fluoropolymer products released PFOA and PFBS into air and wastewater for decades. Chemours in Fayetteville NC, 3M in Decatur AL, and DuPont in Parkersburg WV are the most notorious. GenX – the PFAS that replaced PFOA after health concerns – now contaminates Wilmington at levels higher than the compound it replaced.
Airports. Commercial airports used AFFF for decades during training exercises and runway foam applications. Newark, West Palm Beach, and Rockford all have major airports that contributed to groundwater contamination. The foam soaks into soil, then leaches into aquifers that supply drinking water.
But here's the thing: we're not sure this list is stable. The UCMR5 program tested large systems, but thousands of smaller utilities haven't reported data yet. Some of the worst contamination might be in towns too small to make this ranking.
The EPA finalized enforceable PFAS limits in April 2024. Water systems have until 2027 to test, and until 2029 to comply if they exceed the limits.
What compliance looks like depends on the source. Granular activated carbon (GAC) filters can remove PFAS, but they're expensive at municipal scale – $1-3 million for a mid-sized system, plus ongoing media replacement costs. Ion exchange resins work too. Reverse osmosis is overkill for most cities but gets used when PFAS levels are extreme.
According to the EPA's economic analysis, roughly 6-10% of public water systems will need treatment upgrades. The agency estimates compliance costs at $772 million annually across all affected systems. Smaller utilities will struggle more – the per-household cost in a town of 5,000 is much higher than in a city of 500,000.
Some cities are suing the manufacturers. Philadelphia, Wilmington, and Parchment have all filed claims against 3M, DuPont, and Chemours to recover cleanup costs. Settlements are starting to roll in – 3M agreed to a $10.3 billion deal in 2023 to settle claims from public water systems nationwide.
Not even close. The cities on this list have high reported numbers because they serve large populations and got tested early. But PFAS contamination hits rural areas just as hard – sometimes harder, because small towns near military bases or manufacturing plants have less infrastructure to treat it.
Private wells are the bigger blind spot. If you're on well water, you're outside the UCMR5 testing. You have no idea what your PFAS levels are unless you pay for testing yourself. State health departments in Michigan, New Hampshire, and North Carolina offer free or subsidized well testing in known contamination zones. Outside those states, you're on your own.
First, check your local data. Our ZIP code lookup tool pulls the UCMR5 results for your water system. You'll see which PFAS compounds were detected, at what levels, and when the samples were taken.
If your levels are above the EPA limits – or even close – we recommend filtering at the point of use rather than waiting for your utility to install treatment. Honestly, municipal upgrades are going to take years, and the 2029 deadline is a compliance date, not a "water is safe" date.
Reverse osmosis and activated carbon filters both remove PFAS effectively. RO systems strip out 95%+ of PFOA, PFOS, and other long-chain PFAS. Carbon filters are cheaper and work well for moderate contamination (under 100 ppt), but they need media replacement every 6-12 months depending on your water volume and contamination load.
Pitcher filters and fridge filters are hit or miss. Some are NSF-certified for PFOA/PFOS removal, most aren't. Check the spec sheet – if it doesn't explicitly say "NSF P473" or list PFAS removal, assume it doesn't work.
The cities on this list aren't outliers. They're early data points in a contamination crisis that's only starting to be measured. The EPA tested for 29 PFAS compounds in UCMR5. There are over 12,000 PFAS chemicals in existence. We don't have health data for most of them, and we're not testing for most of them.
According to the CDC's National Health and Nutrition Examination Survey (NHANES), PFAS are detectable in the blood of 97% of Americans. The contamination is already widespread. What we're doing now is figuring out how widespread and how bad.
The April 2024 EPA rule is the first time the federal government has set enforceable limits on any PFAS compound. That's progress. But it's also 50 years after 3M's internal research showed PFOS accumulates in human blood and doesn't break down. The gap between "we knew" and "we regulated" is the story here.
Which US city has the worst PFAS contamination? Wilmington, North Carolina has the highest combined PFAS levels in EPA UCMR5 testing at 327 parts per trillion, driven largely by GenX contamination from the Chemours Fayetteville Works plant. Philadelphia and Newark rank second and third.
Are PFAS levels going down in these cities? Most cities saw stable or slightly declining PFAS levels between 2023 and 2025 testing rounds, but the declines are modest – typically 5-15%. Some cities like Wilmington saw increases as GenX replaced legacy PFOA. Water systems have until 2029 to meet EPA limits.
Should I move if my city is on this list? Moving isn't necessary if you filter your water. Point-of-use reverse osmosis or activated carbon systems remove 95%+ of PFAS. Focus on what you drink and cook with – those are your primary exposure routes. Showering and washing dishes contribute far less to total PFAS intake.
Why are so many military cities on this list? The Department of Defense used AFFF (aqueous film-forming foam) containing PFOS at over 700 bases from the 1970s through 2020 for firefighting training and aircraft hangar suppression systems. The foam soaked into soil and groundwater, contaminating nearby drinking water sources. Military-linked contamination explains at least 12 of the 25 cities on this list.
Do water filters actually remove PFAS or is that marketing? NSF-certified filters work. Look for NSF/ANSI Standard 53 (carbon filters) or NSF P473 (specific PFOA/PFOS reduction). Reverse osmosis removes 95%+ of all PFAS. Standard carbon pitcher filters without NSF P473 certification typically remove less than 50%. Check the product spec sheet – if PFAS removal isn't listed with test data, it probably doesn't work.
Which US city has the worst PFAS contamination? Wilmington, North Carolina has the highest combined PFAS levels in EPA UCMR5 testing at 327 parts per trillion, driven largely by GenX contamination from the Chemours Fayetteville Works plant. Philadelphia and Newark rank second and third.
Are PFAS levels going down in these cities? Most cities saw stable or slightly declining PFAS levels between 2023 and 2025 testing rounds, but the declines are modest – typically 5-15%. Some cities like Wilmington saw increases as GenX replaced legacy PFOA. Water systems have until 2029 to meet EPA limits.
Should I move if my city is on this list? Moving isn't necessary if you filter your water. Point-of-use reverse osmosis or activated carbon systems remove 95%+ of PFAS. Focus on what you drink and cook with – those are your primary exposure routes. Showering and washing dishes contribute far less to total PFAS intake.
Why are so many military cities on this list? The Department of Defense used AFFF (aqueous film-forming foam) containing PFOS at over 700 bases from the 1970s through 2020 for firefighting training and aircraft hangar suppression systems. The foam soaked into soil and groundwater, contaminating nearby drinking water sources. Military-linked contamination explains at least 12 of the 25 cities on this list.
Do water filters actually remove PFAS or is that marketing? NSF-certified filters work. Look for NSF/ANSI Standard 53 (carbon filters) or NSF P473 (specific PFOA/PFOS reduction). Reverse osmosis removes 95%+ of all PFAS. Standard carbon pitcher filters without NSF P473 certification typically remove less than 50%. Check the product spec sheet – if PFAS removal isn't listed with test data, it probably doesn't work.