Iowa water quality by county
99 counties with public water systems. Pick a county to see every system that serves it.
| County | Active systems | People served | Share with violations, 3 yr | Serious violators | Health flags |
|---|---|---|---|---|---|
| Adair County | 7 | 28,393 | 0 | 0 | |
| Adams County | 3 | 25,113 | 0 | 0 | |
| Allamakee County | 34 | 10,414 | 0 | 0 | |
| Appanoose County | 6 | 40,200 | 0 | 0 | |
| Audubon County | 5 | 3,272 | 0 | 0 | |
| Benton County | 23 | 19,015 | 0 | 0 | |
| Black Hawk County | 18 | 161,165 | 0 | 0 | |
| Boone County | 13 | 32,746 | 0 | 0 | |
| Bremer County | 16 | 56,553 | 0 | 0 | |
| Buchanan County | 20 | 13,086 | 0 | 0 | |
| Buena Vista County | 13 | 24,469 | 0 | 0 | |
| Butler County | 17 | 47,188 | 0 | 0 | |
| Calhoun County | 14 | 8,032 | 0 | 0 | |
| Carroll County | 13 | 19,877 | 0 | 0 | |
| Cass County | 14 | 10,945 | 0 | 0 | |
| Cedar County | 28 | 14,112 | 1 | 1 | |
| Cerro Gordo County | 34 | 39,964 | 1 | 0 | |
| Cherokee County | 12 | 13,156 | 0 | 0 | |
| Chickasaw County | 21 | 7,872 | 0 | 0 | |
| Clarke County | 4 | 31,060 | 0 | 0 | |
| Clay County | 6 | 19,356 | 0 | 0 | |
| Clayton County | 45 | 13,403 | 0 | 1 | |
| Clinton County | 29 | 40,325 | 0 | 0 | |
| Crawford County | 10 | 15,526 | 0 | 0 | |
| Dallas County | 23 | 147,667 | 0 | 0 | |
| Davis County | 3 | 36,056 | 0 | 0 | |
| Decatur County | 6 | 59,209 | 1 | 0 | |
| Delaware County | 28 | 9,400 | 0 | 0 | |
| Des Moines County | 11 | 43,019 | 0 | 0 | |
| Dickinson County | 14 | 14,398 | 0 | 0 | |
| Dubuque County | 74 | 92,880 | 0 | 1 | |
| Emmet County | 11 | 8,005 | 0 | 0 | |
| Fayette County | 23 | 14,592 | 0 | 0 | |
| Floyd County | 18 | 12,330 | 0 | 0 | |
| Franklin County | 20 | 10,347 | 0 | 0 | |
| Fremont County | 13 | 5,711 | 0 | 0 | |
| Greene County | 6 | 11,998 | 0 | 0 | |
| Grundy County | 9 | 46,025 | 0 | 0 | |
| Guthrie County | 11 | 7,933 | 0 | 0 | |
| Hamilton County | 14 | 20,411 | 0 | 0 | |
| Hancock County | 18 | 7,764 | 0 | 0 | |
| Hardin County | 23 | 51,741 | 0 | 0 | |
| Harrison County | 20 | 10,181 | 0 | 0 | |
| Henry County | 11 | 23,991 | 0 | 1 | |
| Howard County | 21 | 7,302 | 0 | 0 | |
| Humboldt County | 13 | 7,145 | 0 | 1 | |
| Ida County | 7 | 5,319 | 0 | 0 | |
| Iowa County | 15 | 13,265 | 0 | 0 | |
| Jackson County | 26 | 12,876 | 1 | 1 | |
| Jasper County | 12 | 64,044 | 0 | 0 | |
| Jefferson County | 10 | 61,798 | 0 | 0 | |
| Johnson County | 126 | 193,432 | 1 | 2 | |
| Jones County | 37 | 16,079 | 1 | 2 | |
| Keokuk County | 12 | 23,108 | 0 | 0 | |
| Kossuth County | 27 | 10,881 | 0 | 0 | |
| Lee County | 7 | 35,911 | 0 | 0 | |
| Linn County | 82 | 224,589 | 3 | 1 | |
| Louisa County | 22 | 9,612 | 1 | 1 | |
| Lucas County | 3 | 37,858 | 0 | 0 | |
| Lyon County | 12 | 12,196 | 0 | 0 | |
| Madison County | 5 | 48,287 | 0 | 0 | |
| Mahaska County | 4 | 25,666 | 0 | 0 | |
| Marion County | 13 | 30,229 | 0 | 0 | |
| Marshall County | 14 | 71,541 | 0 | 0 | |
| Mills County | 17 | 8,756 | 0 | 0 | |
| Mitchell County | 17 | 6,921 | 0 | 0 | |
| Monona County | 14 | 6,465 | 0 | 0 | |
| Monroe County | 3 | 37,193 | 0 | 0 | |
| Montgomery County | 5 | 11,256 | 0 | 0 | |
| Muscatine County | 40 | 38,948 | 0 | 0 | |
| O'Brien County | 7 | 11,182 | 0 | 0 | |
| Osceola County | 7 | 13,222 | 0 | 0 | |
| Page County | 9 | 15,993 | 0 | 0 | |
| Palo Alto County | 8 | 15,555 | 0 | 0 | |
| Plymouth County | 13 | 17,703 | 0 | 0 | |
| Pocahontas County | 12 | 5,668 | 0 | 0 | |
| Polk County | 39 | 565,617 | 0 | 0 | |
| Pottawattamie County | 33 | 85,108 | 1 | 1 | |
| Poweshiek County | 8 | 15,352 | 0 | 1 | |
| Ringgold County | 4 | 23,061 | 0 | 0 | |
| Sac County | 9 | 8,496 | 0 | 0 | |
| Scott County | 78 | 172,135 | 0 | 0 | |
| Shelby County | 9 | 11,941 | 0 | 0 | |
| Sioux County | 16 | 38,678 | 0 | 0 | |
| Story County | 21 | 158,728 | 0 | 0 | |
| Tama County | 13 | 25,305 | 0 | 0 | |
| Taylor County | 4 | 24,181 | 0 | 0 | |
| Union County | 2 | 28,329 | 0 | 0 | |
| Van Buren County | 8 | 36,195 | 0 | 0 | |
| Wapello County | 6 | 44,794 | 0 | 0 | |
| Warren County | 14 | 57,488 | 0 | 0 | |
| Washington County | 25 | 33,345 | 0 | 0 | |
| Wayne County | 6 | 36,392 | 0 | 0 | |
| Webster County | 29 | 38,572 | 0 | 0 | |
| Winnebago County | 19 | 9,425 | 0 | 0 | |
| Winneshiek County | 43 | 14,742 | 1 | 1 | |
| Woodbury County | 32 | 99,514 | 0 | 0 | |
| Worth County | 14 | 8,762 | 0 | 0 | |
| Wright County | 22 | 12,136 | 0 | 0 |
under 30% 30 to 59% 60% and over
About this data
Share with violations counts any violation in the past three years, including monitoring and reporting lapses. Counts cover active systems; systems serving more than one county are counted in each.
Source: the U.S. EPA's Enforcement and Compliance History Online system (ECHO), which publishes the federal Safe Drinking Water Information System. EPA's terms and values are shown as published. The Iowa records are from EPA's data refresh of Oct 7, 2026; EPA refreshes this data quarterly, and states report to EPA with a lag of three to six months, so the newest violations may not appear yet. Retrieved from ECHO on Oct 11, 2026.