Does a detection mean the water is unsafe or out of compliance?

No. UCMR 5 is monitoring data and does not indicate compliance or noncompliance with any drinking-water standard. It reports the highest single detected result at the entry point, which is information you can act on by testing your own tap and choosing a certified filter.

PFAS detected in Connecticut water systems

Q: Which Connecticut water systems had PFAS detected in EPA UCMR 5?

EPA UCMR 5 detected PFOA or PFOS at or above 6 parts per trillion in 16 large Connecticut public water systems (each serving more than 10,000 people). Select a system to see the specific PFAS and highest levels detected.

EPA UCMR 5 monitoring (2023–2025) detected PFOA or PFOS at or above 6 parts per trillion in these 16 large Connecticut public water systems, each serving more than 10,000 people. Select a system to see exactly what was detected and the certified filters that reduce it.

Connecticut systems, highest detections first

Water system	PFOA (ppt)	PFOS (ppt)	vs. 4 ppt reference
Norwich Public Utilities	6.7	16.2	4×
Manchester Water Department	13	16	4×
Wallingford Water Department	—	13.9	3.5×
CTWC - Shoreline Region-Guilford System	6	12	3×
Norwalk First Taxing District	9.5	11.2	2.8×
Aquarion Water Co of CT-Main System	10.9	6.6	2.7×
Regional Water Authority	7.1	10.7	2.7×
Meriden Water Division	6.1	9.5	2.4×
East Lyme Water & Sewer Commission	9.2	7.2	2.3×
Hazardville Water Company	8.6	5.4	2.1×
Aquarion Water Co of CT-Valley System	8.1	6.9	2×
Avon Water Co.	7	8	2×
CTWC - Northern Reg-Western System	8	6	2×
Southington Water Department	8	6	2×
Valley Water Systems, Inc.	5.2	6.8	1.7×
CTWC - Unionville System	6	6	1.5×

Highest single EPA UCMR 5 detections (2023–2025), in parts per trillion. The last column is the multiple of the 4 ppt federal reference level for PFOA/PFOS — shown as context only, not a compliance or health determination. — means the compound was not detected at or above 6 ppt.

Not sure what's in your own water? Test it first, then run the selector for a recommendation matched to your home, or read what PFAS is and how it's removed.