Private Well Water Testing in Iowa
County-by-county USGS area-risk estimates for private wells across Iowa — arsenic exceedance probability and private-well population — plus how to test your own well at a Iowa-certified laboratory.
Iowa private-well risk summary
Counties covered
99
Iowa counties with modeled risk data.
People on private wells
area estimate501,221
estimated across covered Iowa counties.
Average arsenic risk
area estimate13%
average modeled chance a well exceeds 10 µg/L arsenic across covered counties.
Iowa counties
- Linn County5% arsenic exceedance (area estimate)23,934 people on private wells
- Dubuque County5% arsenic exceedance (area estimate)20,265 people on private wells
- Johnson County11% arsenic exceedance (area estimate)16,285 people on private wells
- Pottawattamie County8% arsenic exceedance (area estimate)15,751 people on private wells
- Black Hawk County5% arsenic exceedance (area estimate)13,082 people on private wells
- Scott County17% arsenic exceedance (area estimate)11,282 people on private wells
- Warren County16% arsenic exceedance (area estimate)10,706 people on private wells
- Clinton County12% arsenic exceedance (area estimate)10,564 people on private wells
- Muscatine County9% arsenic exceedance (area estimate)10,117 people on private wells
- Polk County24% arsenic exceedance (area estimate)9,985 people on private wells
- Benton County8% arsenic exceedance (area estimate)8,931 people on private wells
- Delaware County8% arsenic exceedance (area estimate)8,577 people on private wells
- Clayton County7% arsenic exceedance (area estimate)8,141 people on private wells
- Lee County10% arsenic exceedance (area estimate)8,108 people on private wells
- Winneshiek County4% arsenic exceedance (area estimate)8,062 people on private wells
- Buchanan County5% arsenic exceedance (area estimate)8,039 people on private wells
- Woodbury County23% arsenic exceedance (area estimate)7,998 people on private wells
- Dallas County22% arsenic exceedance (area estimate)7,943 people on private wells
- Jones County10% arsenic exceedance (area estimate)7,863 people on private wells
- Jackson County7% arsenic exceedance (area estimate)7,460 people on private wells
- Des Moines County9% arsenic exceedance (area estimate)7,459 people on private wells
- Story County37% arsenic exceedance (area estimate)7,385 people on private wells
- Bremer County7% arsenic exceedance (area estimate)7,320 people on private wells
- Washington County10% arsenic exceedance (area estimate)7,032 people on private wells
- Madison County8% arsenic exceedance (area estimate)6,886 people on private wells
- Fayette County2% arsenic exceedance (area estimate)6,831 people on private wells
- Plymouth County12% arsenic exceedance (area estimate)6,779 people on private wells
- Cedar County11% arsenic exceedance (area estimate)6,407 people on private wells
- Allamakee County5% arsenic exceedance (area estimate)6,375 people on private wells
- Webster County12% arsenic exceedance (area estimate)6,017 people on private wells
- Butler County4% arsenic exceedance (area estimate)5,854 people on private wells
- Cerro Gordo County6% arsenic exceedance (area estimate)5,633 people on private wells
- Harrison County8% arsenic exceedance (area estimate)5,629 people on private wells
- Mills County6% arsenic exceedance (area estimate)5,415 people on private wells
- Iowa County13% arsenic exceedance (area estimate)5,214 people on private wells
- Boone County11% arsenic exceedance (area estimate)5,198 people on private wells
- Kossuth County32% arsenic exceedance (area estimate)5,141 people on private wells
- Tama County11% arsenic exceedance (area estimate)5,079 people on private wells
- Henry County10% arsenic exceedance (area estimate)4,992 people on private wells
- Chickasaw County9% arsenic exceedance (area estimate)4,968 people on private wells
- Mitchell County4% arsenic exceedance (area estimate)4,852 people on private wells
- Louisa County7% arsenic exceedance (area estimate)4,765 people on private wells
- Floyd County5% arsenic exceedance (area estimate)4,764 people on private wells
- Hardin County12% arsenic exceedance (area estimate)4,527 people on private wells
- Jasper County16% arsenic exceedance (area estimate)4,394 people on private wells
- Grundy County16% arsenic exceedance (area estimate)4,185 people on private wells
- Marion County12% arsenic exceedance (area estimate)3,976 people on private wells
- Keokuk County12% arsenic exceedance (area estimate)3,973 people on private wells
- Franklin County25% arsenic exceedance (area estimate)3,845 people on private wells
- Marshall County24% arsenic exceedance (area estimate)3,636 people on private wells
- Hamilton County12% arsenic exceedance (area estimate)3,586 people on private wells
- Buena Vista County38% arsenic exceedance (area estimate)3,571 people on private wells
- Crawford County4% arsenic exceedance (area estimate)3,485 people on private wells
- Jefferson County13% arsenic exceedance (area estimate)3,477 people on private wells
- Howard County6% arsenic exceedance (area estimate)3,414 people on private wells
- Hancock County13% arsenic exceedance (area estimate)3,404 people on private wells
- Sioux County27% arsenic exceedance (area estimate)3,334 people on private wells
- Guthrie County8% arsenic exceedance (area estimate)3,259 people on private wells
- Winnebago County18% arsenic exceedance (area estimate)3,222 people on private wells
- Carroll County10% arsenic exceedance (area estimate)3,110 people on private wells
- Sac County28% arsenic exceedance (area estimate)3,051 people on private wells
- Shelby County5% arsenic exceedance (area estimate)3,038 people on private wells
- Worth County6% arsenic exceedance (area estimate)3,012 people on private wells
- Monona County12% arsenic exceedance (area estimate)2,997 people on private wells
- Cass County8% arsenic exceedance (area estimate)2,814 people on private wells
- Clarke County12% arsenic exceedance (area estimate)2,784 people on private wells
- Dickinson County32% arsenic exceedance (area estimate)2,784 people on private wells
- Mahaska County7% arsenic exceedance (area estimate)2,743 people on private wells
- Wright County11% arsenic exceedance (area estimate)2,683 people on private wells
- Wapello County13% arsenic exceedance (area estimate)2,610 people on private wells
- Greene County9% arsenic exceedance (area estimate)2,468 people on private wells
- Adair County6% arsenic exceedance (area estimate)2,314 people on private wells
- Lyon County39% arsenic exceedance (area estimate)2,311 people on private wells
- Fremont County9% arsenic exceedance (area estimate)2,307 people on private wells
- Palo Alto County34% arsenic exceedance (area estimate)2,295 people on private wells
- Humboldt County14% arsenic exceedance (area estimate)2,256 people on private wells
- Montgomery County6% arsenic exceedance (area estimate)2,233 people on private wells
- Pocahontas County17% arsenic exceedance (area estimate)2,229 people on private wells
- Ida County8% arsenic exceedance (area estimate)2,198 people on private wells
- Poweshiek County17% arsenic exceedance (area estimate)2,184 people on private wells
- Audubon County10% arsenic exceedance (area estimate)2,137 people on private wells
- Calhoun County16% arsenic exceedance (area estimate)2,093 people on private wells
- Emmet County33% arsenic exceedance (area estimate)1,909 people on private wells
- Cherokee County29% arsenic exceedance (area estimate)1,878 people on private wells
- Decatur County7% arsenic exceedance (area estimate)1,878 people on private wells
- Union County7% arsenic exceedance (area estimate)1,874 people on private wells
- Taylor County4% arsenic exceedance (area estimate)1,797 people on private wells
- Adams County7% arsenic exceedance (area estimate)1,680 people on private wells
- Page County6% arsenic exceedance (area estimate)1,665 people on private wells
- O'Brien County33% arsenic exceedance (area estimate)1,556 people on private wells
- Ringgold County5% arsenic exceedance (area estimate)1,501 people on private wells
- Osceola County33% arsenic exceedance (area estimate)1,478 people on private wells
- Clay County62% arsenic exceedance (area estimate)1,368 people on private wells
- Davis County7% arsenic exceedance (area estimate)1,201 people on private wells
- Van Buren County7% arsenic exceedance (area estimate)1,042 people on private wells
- Appanoose County9% arsenic exceedance (area estimate)1,002 people on private wells
- Lucas County10% arsenic exceedance (area estimate)911 people on private wells
- Wayne County15% arsenic exceedance (area estimate)857 people on private wells
- Monroe County7% arsenic exceedance (area estimate)597 people on private wells
Find a Iowa-certified testing lab
Get your well tested at a Iowa-certified laboratory. We list certification programs by state.
These figures are USGS area estimates: statistical groundwater models describing how likely elevated contaminant levels are across a county. They are not designed to predict the concentration in any single well. Only testing your own well reveals its water quality.
By TapWaterData Editorial
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