EPA UCMR 5 · 2023–2025 monitoring
PFAS in Connecticut drinking water
EPA tested 63 public water systems in Connecticut for PFAS under UCMR 5. 42 of them had at least one detection, a rate of 66.7%, which is 2th highest of the 51 states and territories with comparable testing. Systems with a detection serve roughly 1,808,319 people in Connecticut.
Connecticut systems with the highest PFAS results
Highest single compound result recorded at each system during UCMR 5 monitoring.
| Water system | Population served | Highest result |
|---|---|---|
| Aquarion Water/Nh | 34,000 | 25.1 ppt |
| Mashantucket Pequot Water System | 22,171 | 19.1 ppt |
| Norwich Public Utilities | 36,163 | 16.2 ppt |
| Manchester Water Department | 51,198 | 16 ppt |
| Aquarion-Newtown Regional | 6,054 | 15.9 ppt |
Which PFAS compounds were found in Connecticut?
The compounds detected most often across Connecticut systems were: PFOA (33 systems, regulated at 4 ppt), PFOS (26 systems, regulated at 4 ppt), PFPeA (19 systems), PFHxA (19 systems). Only five PFAS currently carry enforceable federal limits, phased in through 2029 (EPA on PFAS risk). Several of the most commonly detected compounds, including PFPeA and PFBA, have no federal limit at all, which is why a system can be fully compliant and still show detections.
What about lead in Connecticut?
Across the 41 Connecticut systems serving 10,000 people or more, the median lead 90th-percentile result is 0 ppb. The federal action level is 15 ppb, but that is a trigger for utility action rather than a health threshold: no level of lead exposure is considered safe. Lead almost always enters through service lines and household plumbing rather than the treatment plant, so a low statewide median tells you about the systems, not about your building.
How often do Connecticut systems break drinking water law?
Across 505 active community water systems in Connecticut, 166 have recorded at least one health-based Safe Drinking Water Act violation since 2020, a rate of 32.9 percent. Those systems serve about 167,987 people. Nationally the equivalent figure is 58.8 million.
A health-based violation means a contaminant exceeded a legal limit or required treatment was not delivered, as distinct from a missed sampling deadline. Small rural systems dominate these counts everywhere: one operator, no treatment budget, and a few hundred customers. Read it as a picture of a state's smallest utilities more than of its cities. Full national analysis.
Is Connecticut tap water safe to drink?
On the PFAS measure specifically, 66.7 percent of tested Connecticut systems recorded a detection, against a national picture where about a third of tested systems did. That is a statement about the state, not about your tap: within any state, results vary enormously between systems drawing from different sources. The only figure that describes your water is your own utility's, which is why we would rather send you to look it up than have you act on a state average.
For what these compounds are understood to do in the body, see ATSDR on PFAS health effects. One rule worth carrying: a system with no UCMR 5 record has not been shown to be clean. It has not been tested. We never label an untested system as PFAS-free, and neither should anyone else.
How does your own system compare?
Fifty of the largest US water systems, scored against health guidance, every figure linked to its source.