waterbycounty

Ohio Water Quality

Drinking water data for all 88 counties.

Avg Water Score

56.2

State Grade

D

Counties with Data

88

of 88 total

All Ohio Counties

CountyWater Score
Butler County86.0
Cuyahoga County86.0
Delaware County86.0
Erie County86.0
Gallia County86.0
Highland County86.0
Knox County86.0
Marion County86.0
Mercer County86.0
Morrow County86.0
Pike County86.0
Scioto County86.0
Wyandot County86.0
Hamilton County71.8
Mahoning County71.1
Greene County70.8
Lake County70.1
Lucas County70.1
Montgomery County69.8
Clermont County69.7
Franklin County68.8
Summit County68.6
Medina County68.2
Fairfield County67.7
Miami County67.3
Ashtabula County66.8
Licking County66.5
Ross County66.2
Tuscarawas County65.6
Sandusky County65.3
Columbiana County65.1
Union County65.0
Warren County64.5
Ashland County64.4
Wood County63.2
Clinton County62.8
Lawrence County62.6
Lorain County62.6
Washington County62.6
Portage County62.3
Stark County62.0
Champaign County61.5
Jackson County61.4
Allen County60.8
Huron County60.6
Adams County60.1
Auglaize County59.8
Coshocton County59.4
Shelby County59.3
Fayette County57.7
Belmont County55.7
Trumbull County54.8
Wayne County52.2
Meigs County51.8
Preble County51.6
Brown County51.0
Seneca County50.6
Darke County50.4
Pickaway County49.7
Noble County49.3
Williams County48.5
Madison County46.2
Ottawa County45.7
Jefferson County44.4
Vinton County43.0
Logan County42.9
Guernsey County42.6
Richland County42.4
Carroll County42.0
Clark County41.6
Hardin County39.9
Hocking County39.5
Athens County39.0
Geauga County35.7
Hancock County34.4
Monroe County32.5
Crawford County31.9
Holmes County30.8
Muskingum County29.3
Harrison County24.5
Perry County23.9
Putnam County23.7
Morgan County23.6
Paulding County17.9
Van Wert County13.6
Defiance County12.1
Fulton County11.8
Henry County5.9

Concerned about your water quality?

Berkey water filters remove contaminants at home.

Shop Filters →

Sponsored

Frequently Asked Questions

Which county in Ohio has the best water quality?
Butler County has the highest water quality score in Ohio at 86.0/100 (Grade: A), based on EPA SDWIS data.
Which county in Ohio has the most water violations?
Henry County has among the lowest water quality scores in Ohio at 5.9/100. See the individual county page for detailed violation history.
Is the tap water safe to drink in Ohio?
Ohio has an average water quality score of 56.2/100 based on EPA Safe Drinking Water Act compliance data. Individual county scores vary — check your specific county's page for detailed information.
What contaminants are found in Ohio water supplies?
Drinking water quality varies by county and water system. The EPA Safe Drinking Water Information System (SDWIS) tracks violations for contaminants like lead, nitrates, bacteria, and disinfection byproducts. See individual county pages for specific contaminant and violation history.

Data Source

Water quality data sourced from the EPA Safe Drinking Water Information System (SDWIS) via the ECHO enforcement database. Scores reflect compliance history and health-based violation counts.

Disclaimer: This data is informational only. It is not health, legal, or professional advice. For concerns about your specific water supply, contact your local water utility.

← Back to All States

Explore more data for Ohio

Property TaxCost of LivingCrime RateIncomeHealthSchoolsDisaster RiskWeatherCounty Score