waterbycounty

Missouri Water Quality

Drinking water data for all 115 counties.

Avg Water Score

48.8

State Grade

D

Counties with Data

115

of 115 total

All Missouri Counties

CountyWater Score
Atchison County86.0
Barton County86.0
Bollinger County86.0
Boone County86.0
Buchanan County86.0
Callaway County86.0
Carter County86.0
Christian County86.0
Clark County86.0
Clinton County86.0
Cole County86.0
Cooper County86.0
Crawford County86.0
Dallas County86.0
Dent County86.0
Douglas County86.0
Grundy County86.0
Jackson County86.0
Johnson County86.0
Knox County86.0
Laclede County86.0
Linn County86.0
Macon County86.0
Madison County86.0
Maries County86.0
Randolph County86.0
Schuyler County86.0
Shannon County86.0
St. Charles County86.0
St. Louis city86.0
St. Louis County86.0
Worth County86.0
Wright County86.0
Greene County69.5
Cape Girardeau County69.0
Jasper County65.8
Livingston County61.2
Ray County59.8
Polk County59.6
Marion County58.3
Pulaski County58.3
Platte County56.3
Barry County52.1
Jefferson County50.5
Warren County50.3
Camden County49.9
Butler County49.5
Phelps County49.5
Vernon County48.3
Newton County47.0
Lafayette County46.9
Moniteau County46.7
Perry County46.2
Taney County46.1
Oregon County45.8
Audrain County45.5
Ripley County45.0
Daviess County44.7
Osage County44.0
Howell County43.8
Adair County42.8
Saline County42.4
Montgomery County42.0
St. Clair County41.0
Dade County39.7
Webster County39.2
Franklin County38.6
Howard County38.4
Benton County38.2
Dunklin County38.1
Cass County37.1
Gasconade County36.9
Lewis County36.2
Stone County35.4
Carroll County34.6
Clay County34.5
McDonald County33.8
Washington County32.6
Putnam County32.2
Reynolds County30.0
Stoddard County29.3
Nodaway County28.4
Andrew County28.1
Miller County27.5
Pemiscot County25.5
Texas County25.4
Pettis County24.9
Henry County24.5
Lawrence County24.2
Sullivan County24.1
Scott County22.9
Wayne County22.7
Harrison County22.2
New Madrid County20.3
Ralls County19.9
Ste. Genevieve County19.9
Cedar County19.2
Chariton County19.1
Holt County18.2
Mississippi County18.1
Hickory County17.5
St. Francois County16.7
Pike County16.1
Shelby County14.2
Ozark County11.4
Lincoln County11.1
Caldwell County10.9
DeKalb County10.0
Bates County9.6
Morgan County9.5
Scotland County8.4
Gentry County7.1
Iron County5.5
Monroe County4.6
Mercer County4.3

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Frequently Asked Questions

Which county in Missouri has the best water quality?
Atchison County has the highest water quality score in Missouri at 86.0/100 (Grade: A), based on EPA SDWIS data.
Which county in Missouri has the most water violations?
Mercer County has among the lowest water quality scores in Missouri at 4.3/100. See the individual county page for detailed violation history.
Is the tap water safe to drink in Missouri?
Missouri has an average water quality score of 48.8/100 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 Missouri 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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