The short answer: PFAS "forever chemicals" turned up in 85 of Connecticut's 301 public-water ZIP codes, about 28% of the state. The town with the most is Greenwich, where all five tracked PFAS compounds show up in the water. Behind Greenwich, the list is dominated by lower Fairfield County.
Here is the ranking, and exactly how we built it.
This ranking covers public (city) water systems, the water most Connecticut homes receive, which the state tests and updates regularly. Private wells are tested separately and are not included here. If you're on a well, see the private-well note below.
The Connecticut Towns With the Most PFAS
We rank first by how many of the five tracked PFAS compounds appear in a town's public water, then by how often those compounds turn up in a sample. Breadth comes first on purpose. A system with five different PFAS compounds has a messier problem than one with a single high reading.
| Rank | Town | PFAS compounds detected | Share of samples with a detection |
|---|---|---|---|
| 1 | Greenwich | 5 of 5 | up to 59% |
| 2 | Darien | 4 | ~34% |
| 3 | Milford | 4 | ~34% |
| 4 | Bridgeport | 4 | ~34% |
| 5 | Stratford | 4 | ~34% |
| 6 | Fairfield | 4 | ~34% |
| 7 | Stamford | 4 | ~34% |
Why the four-compound towns tie: the six towns above, plus Westport and a few neighbors (about eight communities in all), are served by the same regional water system in lower Fairfield County. So they share nearly identical PFAS results: four compounds, roughly a detection in 34% of samples. The numbers line up because it is literally the same water. This is a regional PFAS footprint, not a run of separate coincidences.
The five compounds Connecticut tracks are PFOA, PFOS, PFHxS, PFBS, and PFHxA. Greenwich is the only town where all five appear.
One clarification, because we publish two PFAS rankings and they name different towns. This page ranks by breadth: how many distinct PFAS compounds turn up. Our other ranking sorts by concentration: the single highest reading. Greenwich leads the first, Norwich leads the second. Neither is "the" answer, and a town can top one and not the other.
The other way to read "worst": the highest reading
Breadth is one lens. The other is concentration: not how many compounds show up, but how much of any one of them. Those two questions have different answers, and we would rather show you both than pick whichever sounds worse.
By concentration, the highest single PFOA or PFOS reading in Connecticut is 16.2 ng/L of PFOS at Norwich Public Utilities, followed by Manchester (16.0) and Aquarion's Newtown system (15.9). Greenwich, which leads on breadth, does not lead on concentration. We publish that ranking in full in Connecticut towns with the most PFAS right now.
We used to rank this section a third way, and we were wrong to. We ranked by how often a sample sat over a 1 part-per-trillion guideline, and reported that some towns were over it in 100% of samples. That number is real but it is empty: the monitoring program does not report any PFAS result below 4 ng/L, so every detection is automatically over a 1 ng/L guideline. "100% of samples over the guideline" was arithmetic, not a finding. We removed it rather than leave a statistic standing that could only ever say one thing.
Want ZIP-level PFAS context? Enter your ZIP code at CheckYourTap.com to review available public-system records associated with that ZIP. The report does not identify a property’s serving utility or measure its tap.
Why 4 Parts Per Trillion Matters
In 2024 the EPA finalized enforceable PFAS limits at 4 parts per trillion for PFOA and PFOS. That is one of the lowest limits the agency has ever set for any drinking-water contaminant, roughly four drops in a billion gallons. The limit sits that low because the health science is serious. PFAS is linked to kidney and testicular cancer, thyroid disease, immune suppression, high cholesterol, and developmental effects in children.
PFAS is called a "forever chemical" because it does not break down in the environment or in your body. It accumulates.
If you are pregnant or mixing infant formula
This is the group that should act first. Infants take in more per pound of body weight than anyone else, and formula mixed with tap water can be the single largest source of PFAS a baby receives. Their developing systems are also the most vulnerable. If you live in one of the towns above and you are pregnant or preparing formula, don't wait for a citywide fix. Test your specific water. If PFAS is present, use a filter certified to remove it for formula preparation. Boiling does not remove PFAS. It concentrates it.
If you are on a private well
Public-system data does not cover private wells, and wells near contamination sources can be worse than the nearby public supply. If you are on a well in or around any town on this list, PFAS testing is worth it. The EPA's PFAS limits speak to the health risk regardless of who tests your water.
How to Get PFAS Out of Your Water
The treatment options are well established. According to NSF International, reverse osmosis filtration certified to NSF/ANSI 58 removes the great majority of PFAS compounds. Activated carbon filters certified to NSF/ANSI 53 for PFOA/PFOS can reduce them as well. A point-of-use system for a single tap costs roughly $300 to $800, which buys you protection now while any larger municipal fix works its way through.
The first step is distinguishing area records from property exposure. A statewide ranking shows broad patterns; only a certified property sample can establish conditions at a tap.
Review available ZIP records: Check your ZIP at CheckYourTap.com for associated public-system PFAS records and other reported contaminants, then confirm the serving utility and tap when making property decisions.
Data source: Connecticut public water system testing, per-ZIP results as published on CheckYourTap.com. Detection and exceedance rates reflect the samples in the state dataset for each ZIP code. Town names reflect the primary municipality for each ZIP code. "Over the health guideline" means the share of samples above the enforceable limit tracked for that compound.
