In EPA UCMR5 testing from 2023-2025, the highest single-sample PFAS totals among systems serving 10,000+ people were in Calhoun, GA (323 ppt across six regulated compounds), Emmaus, PA (313 ppt), and Gadsden, AL (224 ppt). Many hotspots cluster in northwest Georgia and Alabama, downstream of the Dalton carpet industry.
The EPA's most comprehensive PFAS testing program finished sampling in 2025, and the results show contamination is both widespread and concentrated. The highest single samples show PFOA or PFOS at up to about 45 times the new 4 ppt federal limits.
We pulled KYE's copy of the UCMR5 results (about 10,000 public water systems tested) and ranked systems serving at least 10,000 people by their highest single-sample total across six key compounds: PFOA, PFOS, PFNA, PFHxS, PFBS, and HFPO-DA (GenX). Values are KYE's analysis of EPA data, in parts per trillion.
This table shows the water systems with the highest six-compound total in any single UCMR5 sample. The "Largest compound" is the one contributing the most to that sample:
| Rank | Water system (city or area) | State | People served | Highest sample, 6 PFAS (ppt) | PFOA + PFOS in that sample (ppt) | Largest compound | |------|------|-------|------|-------------------------|------|-------------------| | 1 | Calhoun | GA | 53,090 | 323 | 33 | PFBS | | 2 | Emmaus Borough | PA | 14,000 | 313 | 175 | PFOS | | 3 | Gadsden Water Works | AL | 44,637 | 224 | 64 | PFBS | | 4 | Aqua NC Bayleaf (Wake County) | NC | 16,715 | 214 | 21 | PFHxS | | 5 | Tempe | AZ | 165,000 | 188 | 92 | PFHxS | | 6 | Lubeck Public Service District (Wood County) | WV | 11,724 | 188 | 180 | PFOA | | 7 | Shelby County Water Services | AL | 40,101 | 165 | 49 | PFBS | | 8 | Payson | AZ | 17,682 | 152 | 75 | PFBS | | 9 | Atwater | CA | 29,479 | 145 | 78 | PFHxS | | 10 | Safford | AZ | 20,600 | 144 | not detected | PFBS | | 11 | Augusta-Richmond County | GA | 204,000 | 138 | 81 | PFHxS | | 12 | LaFayette | GA | 18,177 | 136 | 87 | PFOS | | 13 | Emerald Coast Utilities Authority (Pensacola) | FL | 242,172 | 133 | 62 | PFHxS | | 14 | Prattville | AL | 46,614 | 130 | 42 | PFBS | | 15 | Wetumpka | AL | 10,137 | 130 | 48 | PFBS | | 16 | Alabaster | AL | 41,061 | 125 | 40 | PFBS | | 17 | Pell City | AL | 17,586 | 115 | 21 | PFBS | | 18 | Brookwood Community Water System (Cumberland County) | NC | 15,380 | 111 | 37 | PFBS | | 19 | Moses Lake | WA | 32,428 | 111 | 52 | PFHxS | | 20 | Clanton | AL | 13,500 | 108 | 46 | PFBS | | 21 | Floyd County (Rome area) | GA | 46,143 | 107 | 14 | PFBS | | 22 | Savannah Valley Utility District | TN | 30,571 | 107 | 53 | PFBS | | 23 | Tri-Community Water System (Millbrook) | AL | 11,832 | 99 | 26 | PFBS | | 24 | Arizona Water Co. Pinal Valley | AZ | 134,432 | 97 | not detected | PFBS | | 25 | Ocala | FL | 66,449 | 95 | 45 | PFHxS |
The EPA's 2024 maximum contaminant levels (MCLs) set enforceable limits at 4 ppt for PFOA and PFOS individually. PFNA, PFHxS and GenX are limited to 10 ppt each, and a "hazard index" calculation covers mixtures of those three plus PFBS.
Most systems in this ranking had at least one sample above the 4 ppt PFOA or PFOS limit, some by a wide margin: Lubeck's top sample had about 180 ppt of PFOA, roughly 45 times the limit. Two systems (Safford and Arizona Water's Pinal Valley system) were driven almost entirely by PFBS, which has no individual limit. Compliance is judged on running annual averages, not single samples, 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.
A few patterns stand out on this list.
The carpet belt. Nine of the 25 systems (Calhoun, LaFayette, and Floyd County in Georgia, plus Gadsden, Pell City, Shelby County, Clanton, Wetumpka, and Millbrook in Alabama) sit in northwest Georgia near Dalton, the center of the US carpet industry, which used PFAS-based stain-resistant treatments for decades, or in central and northeast Alabama, several of them along the Coosa River that flows downstream from that region. Prattville and Alabaster are nearby. Most of these systems are dominated by PFBS, a shorter-chain PFAS.
Chemical manufacturing. Plants making Teflon, Scotchgard, and other fluoropolymer products released PFAS into air and wastewater for decades. Lubeck Public Service District in West Virginia is near DuPont's (now Chemours') Washington Works plant outside Parkersburg and was one of the water districts in the original C8 class action over PFOA. In North Carolina, GenX from Chemours' Fayetteville Works plant contaminated the Cape Fear River, which supplies Wilmington; Wilmington's utility added granular activated carbon treatment in 2022, and its UCMR5 finished-water samples showed no GenX detections.
Military bases and airports. Firefighting foam (AFFF) used at military bases and airports since the 1970s contained large amounts of PFOS and related compounds. The Department of Defense is assessing more than 700 installations for known or suspected PFAS releases. Atwater, California sits next to the former Castle Air Force Base, and Moses Lake, Washington next to the former Larson Air Force Base; see our military base PFAS tracker for more.
But here's the thing: this list isn't the whole picture. UCMR5 covered every system serving more than 3,300 people plus only a sample of smaller ones, and this ranking leaves out systems under 10,000 people. Some of the worst contamination is in towns too small to make it.
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. In May 2026 the EPA proposed rescinding all but the PFOA and PFOS limits and letting systems extend compliance to 2031.
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 to take action. The agency estimated compliance costs at about $1.5 billion a year 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.
Many water systems sued the manufacturers to recover cleanup costs, and settlements are now paying out: 3M agreed to a $10.3 billion deal in 2023 to settle claims from public water systems nationwide.
Not even close. The systems on this list stand out partly because UCMR5 tested every system of their size. 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 list PFOA/PFOS under NSF/ANSI 53 or 58, assume it isn't certified for PFAS.
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? Among systems serving 10,000+ people, Calhoun, Georgia had the highest single-sample total in KYE's analysis of EPA UCMR5 data: about 323 parts per trillion across six regulated PFAS, mostly PFBS. Emmaus, Pennsylvania (about 313 ppt, mostly PFOS) and Gadsden, Alabama (about 224 ppt) rank second and third.
Are PFAS levels going down in these cities? UCMR5 was a single sampling round from 2023 to 2025, so it can't show trends on its own. Many systems with high results are adding treatment, as Wilmington, North Carolina did with granular activated carbon in 2022. Water systems have until 2029 to meet EPA limits, and EPA has proposed extending the PFOA/PFOS deadline to 2031.
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.
Do military bases cause PFAS contamination? Often, yes. The military used AFFF (aqueous film-forming foam) containing PFOS and related compounds for firefighting training and hangar fire suppression since the 1970s, and the Department of Defense is assessing more than 700 installations for known or suspected PFAS releases. The foam soaked into soil and groundwater, contaminating nearby drinking water sources. In this UCMR5 ranking, though, the largest cluster is in the Georgia and Alabama carpet belt, not around bases.
Do water filters actually remove PFAS or is that marketing? NSF-certified filters work. Look for NSF/ANSI Standard 53 (carbon filters) or 58 (reverse osmosis) with PFOA/PFOS reduction listed. Reverse osmosis removes 95%+ of all PFAS. Carbon pitcher filters without a PFAS certification have no verified PFAS performance and may remove much less. 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? Among systems serving 10,000+ people, Calhoun, Georgia had the highest single-sample total in KYE's analysis of EPA UCMR5 data: about 323 parts per trillion across six regulated PFAS, mostly PFBS. Emmaus, Pennsylvania (about 313 ppt, mostly PFOS) and Gadsden, Alabama (about 224 ppt) rank second and third.
Are PFAS levels going down in these cities? UCMR5 was a single sampling round from 2023 to 2025, so it can't show trends on its own. Many systems with high results are adding treatment, as Wilmington, North Carolina did with granular activated carbon in 2022. Water systems have until 2029 to meet EPA limits, and EPA has proposed extending the PFOA/PFOS deadline to 2031.
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.
Do military bases cause PFAS contamination? Often, yes. The military used AFFF (aqueous film-forming foam) containing PFOS and related compounds for firefighting training and hangar fire suppression since the 1970s, and the Department of Defense is assessing more than 700 installations for known or suspected PFAS releases. The foam soaked into soil and groundwater, contaminating nearby drinking water sources. In this UCMR5 ranking, though, the largest cluster is in the Georgia and Alabama carpet belt, not around bases.
Do water filters actually remove PFAS or is that marketing? NSF-certified filters work. Look for NSF/ANSI Standard 53 (carbon filters) or 58 (reverse osmosis) with PFOA/PFOS reduction listed. Reverse osmosis removes 95%+ of all PFAS. Carbon pitcher filters without a PFAS certification have no verified PFAS performance and may remove much less. Check the product spec sheet – if PFAS removal isn't listed with test data, it probably doesn't work.