Well water hardness in Iowa
Across 72 counties of Iowa, the median well sampled by the USGS has 19.5 gpg of hardness. Counties range from 12 gpg (Muscatine County) to 28.6 gpg (Plymouth County).
Millions of American households drink water from their own well. No utility tests that water and no water quality report covers it. These pages summarise the hardness the U.S. Geological Survey measured in wells county by county, so you know what to expect before you test your own well.
Counties, hardest first
| gpg | mg/L | wells | ||
|---|---|---|---|---|
| Plymouth County | 28.6 | 490 | 23 | very hard |
| Lyon County | 28.3 | 485 | 16 | very hard |
| Webster County | 28 | 480 | 25 | very hard |
| Cherokee County | 26.3 | 450 | 22 | very hard |
| Ida County | 26.3 | 450 | 13 | very hard |
| Kossuth County | 26.3 | 450 | 19 | very hard |
| Sac County | 26 | 445 | 16 | very hard |
| Crawford County | 25.7 | 440 | 31 | very hard |
| Monona County | 25.7 | 440 | 32 | very hard |
| O'Brien County | 25.4 | 435 | 16 | very hard |
| Woodbury County | 24.5 | 419 | 38 | very hard |
| Greene County | 23.9 | 410 | 27 | very hard |
| Harrison County | 23.9 | 410 | 33 | very hard |
| Hamilton County | 23.6 | 405 | 50 | very hard |
| Boone County | 23.4 | 400 | 13 | very hard |
| Shelby County | 23.4 | 400 | 26 | very hard |
| Humboldt County | 22.8 | 390 | 18 | very hard |
| Audubon County | 21.9 | 375 | 12 | very hard |
| Dallas County | 21.9 | 375 | 32 | very hard |
| Pottawattamie County | 21.9 | 375 | 30 | very hard |
| Marshall County | 21.8 | 374 | 24 | very hard |
| Monroe County | 21.6 | 370 | 11 | very hard |
| Wright County | 21.5 | 368 | 14 | very hard |
| Polk County | 21.4 | 367 | 22 | very hard |
| Carroll County | 21.2 | 363 | 55 | very hard |
| Grundy County | 21 | 359 | 20 | very hard |
| Hardin County | 20.8 | 356 | 80 | very hard |
| Hancock County | 20.7 | 355 | 16 | very hard |
| Jasper County | 20.4 | 350 | 36 | very hard |
| Mills County | 20.4 | 350 | 15 | very hard |
| Story County | 20.4 | 350 | 27 | very hard |
| Washington County | 20.2 | 345 | 13 | very hard |
| Tama County | 20 | 342 | 27 | very hard |
| Henry County | 19.9 | 340 | 10 | very hard |
| Winnebago County | 19.6 | 335 | 11 | very hard |
| Franklin County | 19.5 | 334 | 16 | very hard |
| Worth County | 19.5 | 334 | 11 | very hard |
| Fayette County | 19.5 | 334 | 22 | very hard |
| Cerro Gordo County | 19.4 | 333 | 14 | very hard |
| Scott County | 19.4 | 333 | 16 | very hard |
| Dubuque County | 19.3 | 330 | 19 | very hard |
| Johnson County | 19.3 | 330 | 21 | very hard |
| Mahaska County | 19.3 | 330 | 12 | very hard |
| Marion County | 19.3 | 330 | 21 | very hard |
| Benton County | 19 | 325 | 27 | very hard |
| Keokuk County | 19 | 325 | 22 | very hard |
| Cedar County | 18.8 | 323 | 14 | very hard |
| Fremont County | 18.4 | 315 | 19 | very hard |
| Jones County | 18.1 | 310 | 17 | very hard |
| Winneshiek County | 17.9 | 306 | 14 | very hard |
| Iowa County | 17.6 | 302 | 81 | very hard |
| Howard County | 17.5 | 300 | 11 | very hard |
| Jackson County | 17.5 | 300 | 22 | very hard |
| Clayton County | 16.6 | 285 | 27 | very hard |
| Des Moines County | 16.3 | 279 | 15 | very hard |
| Floyd County | 16.2 | 278 | 18 | very hard |
| Bremer County | 16.2 | 277 | 16 | very hard |
| Lee County | 16.2 | 277 | 16 | very hard |
| Black Hawk County | 16 | 274 | 32 | very hard |
| Delaware County | 15.8 | 270 | 13 | very hard |
| Linn County | 15.8 | 270 | 152 | very hard |
| Clinton County | 15.5 | 265 | 22 | very hard |
| Buchanan County | 15.4 | 264 | 19 | very hard |
| Guthrie County | 15.4 | 264 | 41 | very hard |
| Warren County | 15.2 | 260 | 18 | very hard |
| Page County | 14.9 | 255 | 12 | very hard |
| Chickasaw County | 14.7 | 253 | 12 | very hard |
| Louisa County | 14.2 | 244 | 30 | very hard |
| Butler County | 14 | 240 | 23 | very hard |
| Cass County | 13.2 | 226 | 21 | very hard |
| Montgomery County | 12.7 | 218 | 17 | very hard |
| Muscatine County | 12 | 205 | 63 | very hard |
Counties with fewer than 10 sampled wells, or a median outside 5–500 mg/L, are not shown until the figure is reviewed.
Iowa: tap water hardness by city → · Well water hardness by state and county →