Measured, not modelled
Measured well-water hardness for Missouri, county by county: the median of laboratory hardness samples taken at real water wells, in grains per gallon and mg/L as CaCO3, with the number of wells behind every figure.
Most published hardness-by-county tables are estimates from municipal tap water. The figures below are different: they are medians of laboratory samples taken at water wells, from the public record, and every row says how many wells stand behind it. The same table qualifies every lead Hard Water Feed sells, so this page is also how you check our arithmetic — the full method is on the methodology page.
Ratings below use the Water Quality Association scale, in grains per gallon (gpg); 1 gpg is 17.118 mg/L as CaCO3.
| Rating | Range |
|---|---|
| soft | 0 – 1 gpg |
| slightly hard | 1 – 3.5 gpg |
| moderately hard | 3.5 – 7 gpg |
| hard | 7 – 10.5 gpg |
| very hard | over 10.5 gpg |
Source: Water Quality Portal (USGS & US EPA). Water Quality Portal (USGS NWIS + EPA STORET), siteType Well, 13 analytes. 3049 wells filed a hardness value; 2 had it computed from calcium + magnesium. 364 local cells, 85 counties. 26 counties dropped for straddling the softener threshold. A county appears only when at least 3 distinct wells carry a laboratory hardness result; the 30 of Missouri’s 115 counties not listed fall short of that bar or fall under the note above, and they are left out rather than guessed at.
| County | Median (gpg) | Middle half (gpg) | mg/L CaCO3 | Rating | Wells | Samples |
|---|---|---|---|---|---|---|
| Andrew | 19.6 | 12–24.1 | 336 | very hard | 16 | 16 |
| Atchison | 20.2 | 15.8–27.6 | 346 | very hard | 24 | 24 |
| Audrain | 18.1 | 15.6–19.3 | 310 | very hard | 30 | 30 |
| Barry | 10.5 | 8–12.9 | 180 | very hard | 47 | 47 |
| Barton | 9.9 | 8.8–11.1 | 169 | hard | 33 | 33 |
| Benton | 15.2 | 13.4–19.4 | 260 | very hard | 9 | 9 |
| Bollinger | 14.9 | 13.6–16.9 | 255 | very hard | 6 | 6 |
| Boone | 19.3 | 16.4–25 | 330 | very hard | 83 | 83 |
| Buchanan | 20.3 | 15.8–31 | 347 | very hard | 22 | 22 |
| Butler | 11.4 | 9.3–14.6 | 195 | very hard | 28 | 28 |
| Callaway | 17.5 | 15.9–21.6 | 300 | very hard | 20 | 20 |
| Camden | 16.1 | 15.8–17.4 | 276 | very hard | 8 | 8 |
| Cape Girardeau | 13.4 | 10–16.2 | 229 | very hard | 28 | 28 |
| Carroll | 19.9 | 13.4–39.7 | 341 | very hard | 43 | 43 |
| Carter | 13.5 | 12.3–14.6 | 231 | very hard | 15 | 15 |
| Cedar | 9.9 | 9.6–13 | 169 | hard | 9 | 9 |
| Chariton | 17.5 | 12–87.6 | 300 | very hard | 27 | 27 |
| Christian | 9.3 | 8.3–10.5 | 159 | hard | 12 | 12 |
| Clark | 16.4 | 12.9–20.4 | 281 | very hard | 28 | 28 |
| Clay | 27.2 | 19.1–32.9 | 466 | very hard | 40 | 40 |
| Clinton | 15.2 | 11.7–20.2 | 260 | very hard | 14 | 14 |
| Cole | 17.2 | 15.2–20.3 | 294 | very hard | 22 | 22 |
| Cooper | 16.1 | 14.8–17.3 | 276 | very hard | 16 | 16 |
| Crawford | 11.7 | 9.9–13.4 | 200 | very hard | 20 | 20 |
| Dade | 9.3 | 8.6–13.6 | 159 | hard | 17 | 17 |
| Dallas | 18.7 | 14.8–22.3 | 320 | very hard | 16 | 16 |
| Dent | 11.7 | 10.5–13.1 | 200 | very hard | 17 | 17 |
| Douglas | 14.6 | 14.2–15 | 250 | very hard | 4 | 4 |
| Franklin | 16.7 | 11.7–22.8 | 286 | very hard | 54 | 54 |
| Gasconade | 14.6 | 13.6–17.2 | 250 | very hard | 16 | 16 |
| Gentry | 21.6 | 18–31.6 | 370 | very hard | 12 | 12 |
| Greene | 9.9 | 8.7–12.6 | 169 | hard | 29 | 29 |
| Grundy | 27.5 | 16.4–54.8 | 471 | very hard | 38 | 38 |
| Harrison | 24.5 | 17.4–37.7 | 419 | very hard | 17 | 17 |
| Hickory | 13.4 | 11.7–15.2 | 229 | very hard | 11 | 11 |
| Holt | 26.2 | 17.2–33 | 448 | very hard | 21 | 21 |
| Howell | 12.3 | 11.1–13 | 211 | very hard | 19 | 19 |
| Iron | 11.7 | 10.5–94.2 | 200 | very hard | 13 | 13 |
| Jasper | 13.9 | 10.6–22.2 | 238 | very hard | 100 | 100 |
| Jefferson | 18.1 | 16.1–22.8 | 310 | very hard | 121 | 121 |
| Knox | 20.4 | 16.9–34.5 | 349 | very hard | 5 | 5 |
| Laclede | 15.8 | 11.8–17.5 | 270 | very hard | 12 | 12 |
| Lawrence | 9.7 | 8.8–11.6 | 166 | hard | 24 | 24 |
| Lewis | 15.8 | 11.7–20.4 | 270 | very hard | 23 | 23 |
| Lincoln | 16.4 | 15.2–16.9 | 281 | very hard | 16 | 16 |
| Linn | 15.2 | 12–21.3 | 260 | very hard | 21 | 21 |
| Macon | 61.3 | 14.3–119.8 | 1,049 | very hard | 29 | 29 |
| Maries | 17.5 | 15.2–29.2 | 300 | very hard | 11 | 11 |
| Marion | 15.2 | 12.3–19.9 | 260 | very hard | 9 | 9 |
| Mercer | 46.7 | 17.2–74.5 | 799 | very hard | 16 | 16 |
| Miller | 18.7 | 14.6–20.4 | 320 | very hard | 11 | 11 |
| Moniteau | 15.2 | 13–16.8 | 260 | very hard | 12 | 12 |
| Monroe | 18.7 | 16.6–24 | 320 | very hard | 5 | 5 |
| Montgomery | 19.3 | 16.4–21.6 | 330 | very hard | 15 | 15 |
| Morgan | 15.8 | 11.1–17.5 | 270 | very hard | 7 | 7 |
| Newton | 9.3 | 8.2–11.7 | 159 | hard | 35 | 35 |
| Oregon | 15.8 | 13.2–16.9 | 270 | very hard | 23 | 23 |
| Osage | 17.5 | 16.4–19.3 | 300 | very hard | 11 | 11 |
| Ozark | 15.2 | 14–17.5 | 260 | very hard | 7 | 7 |
| Perry | 18.7 | 12.1–21.8 | 320 | very hard | 14 | 14 |
| Pettis | 16.4 | 13.4–18.1 | 281 | very hard | 19 | 19 |
| Phelps | 17.5 | 15–21 | 300 | very hard | 46 | 46 |
| Pike | 18.7 | 14–20.4 | 320 | very hard | 8 | 8 |
| Platte | 19.9 | 12.7–33.6 | 341 | very hard | 26 | 26 |
| Polk | 11.7 | 11.1–15.2 | 200 | very hard | 7 | 7 |
| Pulaski | 15.3 | 12.9–18.6 | 262 | very hard | 116 | 116 |
| Putnam | 24 | 18.1–30.1 | 411 | very hard | 13 | 13 |
| Reynolds | 90.5 | 11.4–120.5 | 1,549 | very hard | 36 | 36 |
| Ripley | 12.7 | 8.3–16.8 | 217 | very hard | 8 | 8 |
| Saline | 18.7 | 14.3–29.5 | 320 | very hard | 68 | 68 |
| Shannon | 13 | 11.7–16.4 | 223 | very hard | 43 | 43 |
| St. Charles | 18.7 | 15.8–24.5 | 320 | very hard | 167 | 167 |
| St. Clair | 12.9 | 11.7–16.2 | 221 | very hard | 7 | 7 |
| St. Francois | 30.6 | 16.6–40.6 | 524 | very hard | 65 | 65 |
| St. Louis | 17.5 | 12.9–22.2 | 300 | very hard | 122 | 122 |
| Ste. Genevieve | 18.1 | 13.6–22.5 | 310 | very hard | 10 | 10 |
| Stone | 8.8 | 7.6–11.9 | 151 | hard | 9 | 9 |
| Sullivan | 21.6 | 17.5–38.6 | 370 | very hard | 11 | 11 |
| Taney | 15.2 | 14–17.5 | 260 | very hard | 15 | 15 |
| Texas | 13.4 | 11.7–14.6 | 229 | very hard | 23 | 23 |
| Warren | 16.4 | 16.4–21 | 281 | very hard | 15 | 15 |
| Washington | 15.2 | 14–18.7 | 260 | very hard | 11 | 11 |
| Webster | 11.7 | 9.9–14.5 | 200 | very hard | 7 | 7 |
| Worth | 18.4 | 12.4–21.9 | 315 | very hard | 8 | 8 |
| Wright | 12.4 | 10.7–12.9 | 212 | very hard | 12 | 12 |
Yes — the median across 167 measured wells, one reading each in St. Charles County is 18.7 grains per gallon (about 320 mg/L as CaCO3), which is “very hard” on the Water Quality Association scale. The middle half of those wells falls between 15.8 and 24.5 gpg, so individual wells vary widely around the median. This is groundwater measured at other wells in the county, not a reading from any one property.
Yes — the median across 122 measured wells, one reading each in St. Louis County is 17.5 grains per gallon (about 300 mg/L as CaCO3), which is “very hard” on the Water Quality Association scale. The middle half of those wells falls between 12.9 and 22.2 gpg, so individual wells vary widely around the median. This is groundwater measured at other wells in the county, not a reading from any one property.
Yes — the median across 121 measured wells, one reading each in Jefferson County is 18.1 grains per gallon (about 310 mg/L as CaCO3), which is “very hard” on the Water Quality Association scale. The middle half of those wells falls between 16.1 and 22.8 gpg, so individual wells vary widely around the median. This is groundwater measured at other wells in the county, not a reading from any one property.
Yes — the median across 116 measured wells, one reading each in Pulaski County is 15.3 grains per gallon (about 262 mg/L as CaCO3), which is “very hard” on the Water Quality Association scale. The middle half of those wells falls between 12.9 and 18.6 gpg, so individual wells vary widely around the median. This is groundwater measured at other wells in the county, not a reading from any one property.
Yes — the median across 100 measured wells, one reading each in Jasper County is 13.9 grains per gallon (about 238 mg/L as CaCO3), which is “very hard” on the Water Quality Association scale. The middle half of those wells falls between 10.6 and 22.2 gpg, so individual wells vary widely around the median. This is groundwater measured at other wells in the county, not a reading from any one property.
Yes — the median across 83 measured wells, one reading each in Boone County is 19.3 grains per gallon (about 330 mg/L as CaCO3), which is “very hard” on the Water Quality Association scale. The middle half of those wells falls between 16.4 and 25 gpg, so individual wells vary widely around the median. This is groundwater measured at other wells in the county, not a reading from any one property.
Yes — the median across 68 measured wells, one reading each in Saline County is 18.7 grains per gallon (about 320 mg/L as CaCO3), which is “very hard” on the Water Quality Association scale. The middle half of those wells falls between 14.3 and 29.5 gpg, so individual wells vary widely around the median. This is groundwater measured at other wells in the county, not a reading from any one property.
Yes — the median across 65 measured wells, one reading each in St. Francois County is 30.6 grains per gallon (about 524 mg/L as CaCO3), which is “very hard” on the Water Quality Association scale. The middle half of those wells falls between 16.6 and 40.6 gpg, so individual wells vary widely around the median. This is groundwater measured at other wells in the county, not a reading from any one property.
Yes — the median across 54 measured wells, one reading each in Franklin County is 16.7 grains per gallon (about 286 mg/L as CaCO3), which is “very hard” on the Water Quality Association scale. The middle half of those wells falls between 11.7 and 22.8 gpg, so individual wells vary widely around the median. This is groundwater measured at other wells in the county, not a reading from any one property.
Yes — the median across 47 measured wells, one reading each in Barry County is 10.5 grains per gallon (about 180 mg/L as CaCO3), which is “very hard” on the Water Quality Association scale. The middle half of those wells falls between 8 and 12.9 gpg, so individual wells vary widely around the median. This is groundwater measured at other wells in the county, not a reading from any one property.
The answers above cover the 10 counties with the most measured wells; the table covers every county that clears the minimum. If your county isn’t listed, the honest answer is that the public record doesn’t hold enough well samples there for us to say — not that its water is soft.
Hard Water Feed publishes a weekly feed of newly filed domestic wells in these counties, qualified against this same hardness table and sold to one water-treatment business per territory. The territory grid shows what’s open; the category guide explains the mechanism.
Selling water treatment in Missouri? The new wells behind these figures are sold by territory — well water leads in Missouri.
Built from the same data that builds the feed, and regenerated with it — figures on this page change only when the underlying public record does.