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 Wisconsin water systems

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

EPA UCMR 5 detected PFOA or PFOS at or above 6 parts per trillion in 4 large Wisconsin 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 4 large Wisconsin 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.

Wisconsin systems, highest detections first

Water system	PFOA (ppt)	PFOS (ppt)	vs. 4 ppt reference
Marshfield Utilities	—	14	3.5×
Weston Municipal Utilities	5.9	13	3.3×
Hartford Waterworks, WI	6.8	5.5	1.7×
West Bend Waterworks	6.5	—	1.6×

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.