Water quality by county
in Ohio
EPA sampled public water systems across Ohio for PFAS under its UCMR 5 programme. Of the 88 counties, 24 have a reading above a federal limit and 2 have not been sampled at all — which is not a clean result, only an absence of one. Each county below shows what was found, at what concentration, and at which utility.
| county | Population | Worst result | Compound |
|---|---|---|---|
| Warren County | 256,059 | 7.2× | PFOS · 28.9 ng/L |
| Trumbull County | 200,300 | 5.3× | PFOS · 21.2 ng/L |
| Washington County | 58,332 | 5.0× | PFOA · 20 ng/L |
| Mahoning County | 225,786 | 4.8× | PFOS · 19.3 ng/L |
| Clermont County | 214,123 | 4.0× | PFOS · 16 ng/L |
| Greene County | 172,347 | 3.5× | PFOS · 14 ng/L |
| Noble County | 14,269 | 3.3× | PFOA · 13 ng/L |
| Hamilton County | 837,359 | 3.1× | PFOS · 12.4 ng/L |
| Montgomery County | 537,443 | 2.6× | PFOS · 10.5 ng/L |
| Guernsey County | 38,219 | 2.5× | PFOA · 9.8 ng/L |
| Belmont County | 64,692 | 2.0× | PFOA · 8.1 ng/L |
| Meigs County | 21,491 | 1.9× | PFOA · 7.6 ng/L |
| Gallia County | 28,886 | 1.9× | PFOA · 7.5 ng/L |
| Clinton County | 42,019 | 1.8× | PFOS · 7.3 ng/L |
| Summit County | 538,370 | 1.8× | PFOA · 7.3 ng/L |
| Franklin County | 1,356,303 | 1.8× | PFOA · 7.2 ng/L |
| Lawrence County | 55,829 | 1.7× | PFOA · 6.8 ng/L |
| Darke County | 51,462 | 1.6× | PFOS · 6.3 ng/L |
| Scioto County | 71,798 | 1.4× | PFOA · 5.4 ng/L |
| Butler County | 399,542 | 1.3× | PFOA · 5.3 ng/L |
| Wayne County | 116,632 | 1.2× | PFOA · 4.8 ng/L |
| Brown County | 44,292 | 1.2× | PFOA · 4.7 ng/L |
| Delaware County | 237,966 | 1.1× | PFOA · 4.2 ng/L |
| Muskingum County | 86,582 | 1.0× | PFOA · 4 ng/L |
| Pike County | 27,065 | under the limit | PFNA · 5.3 ng/L |
| Fulton County | 42,028 | under the limit | PFNA · 4.6 ng/L |
| Adams County | 27,671 | under the limit | — |
| Allen County | 100,866 | under the limit | — |
| Ashland County | 52,420 | under the limit | — |
| Ashtabula County | 96,906 | under the limit | — |
| Athens County | 63,218 | under the limit | — |
| Auglaize County | 45,922 | under the limit | — |
| Carroll County | 26,460 | under the limit | — |
| Champaign County | 38,907 | under the limit | — |
| Clark County | 134,985 | under the limit | — |
| Columbiana County | 99,823 | under the limit | — |
| Coshocton County | 37,003 | under the limit | — |
| Crawford County | 41,626 | under the limit | — |
| Cuyahoga County | 1,240,594 | under the limit | — |
| Defiance County | 38,644 | under the limit | — |
| Erie County | 73,841 | under the limit | — |
| Fairfield County | 167,762 | under the limit | — |
| Fayette County | 28,782 | under the limit | — |
| Geauga County | 95,362 | under the limit | — |
| Hancock County | 75,016 | under the limit | — |
| Hardin County | 30,402 | under the limit | — |
| Harrison County | 14,042 | under the limit | — |
| Henry County | 27,536 | under the limit | — |
| Highland County | 43,785 | under the limit | — |
| Hocking County | 27,429 | under the limit | — |
| Holmes County | 44,668 | under the limit | — |
| Huron County | 58,168 | under the limit | — |
| Jackson County | 32,723 | under the limit | — |
| Jefferson County | 63,900 | under the limit | — |
| Knox County | 63,848 | under the limit | — |
| Lake County | 232,360 | under the limit | — |
| Licking County | 184,898 | under the limit | — |
| Logan County | 46,085 | under the limit | — |
| Lorain County | 322,030 | under the limit | — |
| Lucas County | 426,291 | under the limit | — |
| Madison County | 45,531 | under the limit | — |
| Marion County | 64,976 | under the limit | — |
| Medina County | 184,625 | under the limit | — |
| Mercer County | 42,648 | under the limit | — |
| Miami County | 111,950 | under the limit | — |
| Monroe County | 13,051 | under the limit | — |
| Morgan County | 13,532 | not sampled | — |
| Morrow County | 35,927 | under the limit | — |
| Ottawa County | 39,692 | under the limit | — |
| Paulding County | 18,755 | under the limit | — |
| Perry County | 35,682 | under the limit | — |
| Pickaway County | 62,158 | under the limit | — |
| Portage County | 163,839 | under the limit | — |
| Preble County | 40,801 | under the limit | — |
| Putnam County | 34,206 | under the limit | — |
| Richland County | 124,853 | under the limit | — |
| Ross County | 76,046 | under the limit | — |
| Sandusky County | 58,866 | under the limit | — |
| Seneca County | 54,730 | under the limit | — |
| Shelby County | 47,952 | under the limit | — |
| Stark County | 374,091 | under the limit | — |
| Tuscarawas County | 92,048 | under the limit | — |
| Union County | 71,721 | under the limit | — |
| Van Wert County | 28,887 | under the limit | — |
| Vinton County | 12,545 | not sampled | — |
| Williams County | 36,554 | under the limit | — |
| Wood County | 133,077 | under the limit | — |
| Wyandot County | 21,394 | under the limit | — |