Ohio PFAS results from EPA's final data
Report published Nov 14, 2026 · EPA UCMR 5 final data file of Oct 15, 2026 (samples collected 2023–2025) · Method · National results →
35 Ohio water systems serving 1.5 million people had PFAS above a 2024 federal limit in EPA's final round of nationwide PFAS testing: 11% of the 331 Ohio systems tested, compared with 11% nationally.
Highest PFOA or PFOS averages in Ohio
- McDonald Village Public Water System McDonald · PFOS17.5 ppt
- Loveland City Public Water System Loveland · PFOS15.9 ppt
- Putnam Community Water Association Public Water System Marietta · PFOA15.3 ppt
- Wright-Patterson AFB Area B Public Water System Wright-Patterson AFB · PFOS14 ppt
- Indian Hill City Public Water System The Village of Indian Hill · PFOS11.7 ppt
- Lordstown Village Public Water System Lordstown · PFOS11.5 ppt
- Canfield City Public Water System Canfield · PFOS11.4 ppt
- Trumbull County – Howland Township Public Water System Howland Center · PFOS10.6 ppt
- Warren Comm Water & Sewer District Association 2 Marietta · PFOA10 ppt
- Western Water Company South Lebanon · PFOS9.8 ppt
- Clermont Public Water System Amelia · PFOS9.2 ppt
- Dayton VA Bldg 410 Water System Dayton · PFOS8.55 ppt
- Caldwell Village Public Water System Caldwell · PFOA8.43 ppt
- Guernsey County Water Dept. Old Washington · PFOA7.8 ppt
- Milford City Public Water System Milford · PFOS7.8 ppt
Chart data as a table
| System | ppt |
|---|---|
| McDonald Village Public Water System · McDonald · PFOS | 17.5 |
| Loveland City Public Water System · Loveland · PFOS | 15.9 |
| Putnam Community Water Association Public Water System · Marietta · PFOA | 15.3 |
| Wright-Patterson AFB Area B Public Water System · Wright-Patterson AFB · PFOS | 14 |
| Indian Hill City Public Water System · The Village of Indian Hill · PFOS | 11.7 |
| Lordstown Village Public Water System · Lordstown · PFOS | 11.5 |
| Canfield City Public Water System · Canfield · PFOS | 11.4 |
| Trumbull County – Howland Township Public Water System · Howland Center · PFOS | 10.6 |
| Warren Comm Water & Sewer District Association 2 · Marietta · PFOA | 10 |
| Western Water Company · South Lebanon · PFOS | 9.8 |
| Clermont Public Water System · Amelia · PFOS | 9.2 |
| Dayton VA Bldg 410 Water System · Dayton · PFOS | 8.55 |
| Caldwell Village Public Water System · Caldwell · PFOA | 8.43 |
| Guernsey County Water Dept. · Old Washington · PFOA | 7.8 |
| Milford City Public Water System · Milford · PFOS | 7.8 |
Largest systems above a limit
| # | System | People served |
|---|---|---|
| 1 | Cincinnati Public Water System Cincinnati Above: PFOS | 800,000 |
| 2 | Montgomery County Water Services 1 Public Water System Kettering Above: PFOS | 150,207 |
| 3 | Dayton Public Water System Dayton Above: PFOS | 141,407 |
| 4 | Clermont Public Water System Amelia Above: PFOS | 133,059 |
| 5 | Western Water Company South Lebanon Above: PFOS | 39,508 |
| 6 | Gallia County Rural Water Association Rio Grande Above: PFOA | 20,995 |
| 7 | Springboro Public Water System Springboro Above: PFOA, PFOS | 19,263 |
| 8 | Marietta City Public Water System Marietta Above: PFOA, PFOS | 18,707 |
| 9 | Wright-Patterson AFB Area A Public Water System Wright-Patterson AFB Above: PFOS | 16,551 |
| 10 | Indian Hill City Public Water System The Village of Indian Hill Above: PFOS | 15,000 |
All 35 Ohio systems above a limit
Every Ohio community water system whose UCMR 5 results averaged above a 2024 federal PFAS limit, largest first. Systems that were not tested are not listed: not tested is not the same as not detected.
Full list: 35 systems, largest first
The same list, with PFOA and PFOS averages, is in the data download.
Which limits were exceeded
| PFAS | Federal limit | Systems above it |
|---|---|---|
| PFOA 147,461 people | 4 ppt | 17 |
| PFOS 1.4 million people | 4 ppt | 21 |
| PFHxS 11,034 people | 10 ppt | 1 |
| PFNA | 10 ppt | 0 |
| GenX (HFPO-DA) | 10 ppt | 0 |
| Hazard Index 11,034 people | 1 | 1 |
"–" in the table above means not detected. A system can be above more than one limit. EPA proposed in May 2026 to rescind the PFHxS, PFNA, GenX and Hazard Index limits. That proposal is not final.
Data and how to cite it
- Download every Ohio water system as CSV (PFOA and PFOS averages, systems above a limit, lead, violations).
- EPA's source file: UCMR 5 occurrence data.
Suggested citation:
Tap Water Results, "Ohio PFAS results from EPA's final UCMR 5 data" (published Nov 14, 2026, EPA data file of Oct 15, 2026). https://tapwaterresults.com/pfas/ohio/
You're welcome to quote and republish these figures with a link back. Questions from reporters: see contact.
Method
For each system we average each entry point's UCMR 5 results (non-detects count as zero, complete sets of samples only) and compare the highest entry-point average with the 2024 federal limit, using EPA's rounding. This is how EPA compares UCMR 5 results to the limits in its own data summary, and our national counts match EPA's published table within 2% (how we check). Results are monitoring data from 2023–2025, not compliance determinations, and treatment installed since then is not reflected. Full method.
Questions
How many Ohio water systems have PFAS above the limit?
35 of the 331 Ohio community water systems EPA tested in 2023–2025 (11%) had at least one entry-point average above a 2024 federal PFAS limit. They serve 1.5 million people. Nationally the share is 11%.
Are these systems violating the law?
Not yet. Systems have until 2029 to meet the 2024 limits, and EPA has proposed moving the PFOA and PFOS deadline to 2031 and rescinding the other limits. EPA's UCMR 5 results are monitoring data and do not determine compliance.
Which systems were tested?
EPA's UCMR 5 tested every community water system serving more than 3,300 people and a representative sample of smaller ones. Systems that were not tested have no federal result, which is not the same as having no PFAS.
All Ohio water systems → · National results → · PFAS results for every state →
Source: U.S. EPA drinking water records and PFAS testing (UCMR 5). How we read the data.