If you want the short answer: PFAS "forever chemicals" were detected in 85 of Connecticut's 301 public-water ZIP codes — about 28% of the state — and 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 honest, data-based 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 by how many of the five tracked PFAS compounds appear in a town's public water (breadth of contamination) first, then by how often samples exceed the health guideline (severity). Breadth comes first on purpose — a system with five different PFAS compounds has a more complex problem than one with a single high reading.
| Rank | Town | PFAS compounds detected | Samples over the health guideline |
|---|---|---|---|
| 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 — along with Westport and a few of their 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 at roughly 34% of samples over the guideline. Their numbers are almost byte-for-byte identical because it is literally the same water. This is a regional PFAS footprint, not a handful of separate coincidences.
The five compounds Connecticut tracks are PFOA, PFOS, PFHxS, PFBS, and PFHxA. Greenwich is the only town where all five appear.
The other way to read "worst": highest exceedance
Breadth isn't the only lens. If you rank by how often a compound is over the guideline, three towns with fewer compounds jump up: Manchester, Chester, and Norwalk each have three PFAS compounds, but with samples exceeding the guideline above 62% — higher than the Fairfield County systems. And three smaller systems — Putnam, Colchester, and Bethel — each had a single PFAS compound over the guideline in 100% of samples. Fewer compounds, but every sample affected. We show you both lenses rather than pick the scarier one.
Want your town's exact PFAS numbers? Enter your ZIP code at CheckYourTap.com — it shows every PFAS compound detected in your water and how it compares to the health limit, free, in about 30 seconds.
Why 4 Parts Per Trillion Matters
In 2024 the EPA finalized enforceable PFAS limits at 4 parts per trillion for PFOA and PFOS. To put that in perspective, 4 parts per trillion is one of the lowest limits the EPA has ever set for any drinking-water contaminant — roughly four drops in a billion gallons. The limit is that low because the science on PFAS is that serious: it 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 have the highest exposure per pound of body weight — formula mixed with tap water can be the single largest source of PFAS a baby receives — and their developing systems are the most vulnerable. If you are in any of the towns above and you are pregnant or preparing formula, do not wait for a citywide fix. Test your specific water, and 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 apply 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, and 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–$800 — immediate protection while any larger municipal fix works its way through.
But the first step is knowing your number. A statewide ranking tells you the pattern; only your address tells you your exposure.
See what's in your water: Check your ZIP at CheckYourTap.com for your town's full PFAS results and the other contaminants tracked there.
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.