Two of three Clermont County water treatment plants showed PFAS contamination in 2025. One plant recorded a single PFOS reading nearly three times the future federal limit, according to the county's annual water quality report.

The Clermont County Public Water System serves Symmes Township and surrounding communities. It is a separate system from the Milford city wells, which also reported PFAS detections in a report we covered Sept. 23.

The county system operates three plants that feed a shared distribution network. Two showed PFAS detections during sampling on May 28 and Dec. 3, 2025. The third plant had no detections.

The highest reading came from the Miami, Goshen, Stonelick plant near Miamiville, which draws groundwater from the Little Miami River Aquifer. PFOS there measured 10.9 parts per trillion on Dec. 3, 2025. The federal maximum contaminant level, or MCL, for PFOS is 4 ppt. An earlier sample on May 28 measured 9.22 ppt.

PFOA at the same plant reached 3.69 ppt in May and 2.79 ppt in December, both below the 4 ppt federal limit.

At the Pierce, Union, Batavia plant near New Palestine, PFOA measured 4.13 ppt on May 28, just above the 4 ppt threshold. A December sample came in at 3.75 ppt. PFOS at that plant measured 1.82 ppt in May and 3.41 ppt in December. The PUB wellfield provides drinking water to about 145,000 Clermont County residents, according to a county notice related to the former Beckjord coal plant site.

The readings are not violations because the federal limits don't take effect until 2029 at the earliest, and compliance will be based on annual averages rather than single samples. The report did not explain why readings above the MCL did not trigger a violation. The county held an unconditioned license to operate the system in 2025.

The Clermont County Water Resources Department said in the report that a detection does not mean the water is unsafe. The department described PFAS as contaminants of emerging concern, noting that research into their health effects is still ongoing.

The U.S. EPA's 2024 drinking water rule set MCLs of 4 ppt for PFOA and PFOS individually. On May 18, 2026, the EPA proposed extending the compliance deadline for those two compounds from 2029 to 2031 while maintaining the 4 ppt limits, according to a Kaplan Kirsch analysis of the proposed rules.

The Ohio EPA reviewed and updated source water assessments for both the MGS and PUB aquifers in 2025. Both carry a high susceptibility rating for contamination, though the county report noted that the rating reflects potential risk, not current water quality.

Residents with questions about the Clermont County water system can contact Tim Neyer at the Clermont County Water Resources Department at (513) 732-7945.