waterbycounty

Iowa Water Quality

Drinking water data for all 99 counties.

Avg Water Score

71.7

State Grade

C

Counties with Data

99

of 99 total

All Iowa Counties

CountyWater Score
Adair County86.0
Adams County86.0
Allamakee County86.0
Appanoose County86.0
Audubon County86.0
Black Hawk County86.0
Bremer County86.0
Buchanan County86.0
Buena Vista County86.0
Cerro Gordo County86.0
Cherokee County86.0
Clay County86.0
Clayton County86.0
Clinton County86.0
Crawford County86.0
Dallas County86.0
Davis County86.0
Delaware County86.0
Emmet County86.0
Fayette County86.0
Floyd County86.0
Franklin County86.0
Fremont County86.0
Greene County86.0
Grundy County86.0
Hamilton County86.0
Hardin County86.0
Harrison County86.0
Henry County86.0
Howard County86.0
Humboldt County86.0
Ida County86.0
Jackson County86.0
Jasper County86.0
Jefferson County86.0
Keokuk County86.0
Kossuth County86.0
Lee County86.0
Louisa County86.0
Lucas County86.0
Lyon County86.0
Madison County86.0
Mahaska County86.0
Marion County86.0
Marshall County86.0
Mitchell County86.0
Monona County86.0
Monroe County86.0
Montgomery County86.0
Muscatine County86.0
O'Brien County86.0
Osceola County86.0
Plymouth County86.0
Pottawattamie County86.0
Ringgold County86.0
Shelby County86.0
Sioux County86.0
Tama County86.0
Taylor County86.0
Union County86.0
Van Buren County86.0
Wapello County86.0
Warren County86.0
Washington County86.0
Wayne County86.0
Winnebago County86.0
Winneshiek County86.0
Worth County86.0
Wright County86.0
Polk County69.8
Linn County69.0
Scott County68.2
Woodbury County67.8
Dubuque County67.1
Story County66.8
Des Moines County66.0
Page County59.4
Dickinson County46.3
Jones County44.5
Chickasaw County41.8
Boone County41.1
Cedar County39.4
Johnson County37.9
Pocahontas County37.5
Hancock County36.4
Benton County36.1
Webster County35.8
Clarke County34.5
Butler County32.4
Guthrie County28.6
Cass County27.6
Carroll County17.6
Sac County17.6
Poweshiek County13.6
Palo Alto County13.1
Iowa County11.3
Calhoun County11.2
Decatur County11.1
Mills County10.8

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Frequently Asked Questions

Which county in Iowa has the best water quality?
Adair County has the highest water quality score in Iowa at 86.0/100 (Grade: A), based on EPA SDWIS data.
Which county in Iowa has the most water violations?
Mills County has among the lowest water quality scores in Iowa at 10.8/100. See the individual county page for detailed violation history.
Is the tap water safe to drink in Iowa?
Iowa has an average water quality score of 71.7/100 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 Iowa 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.

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