Measured, not modelled
Measured well-water hardness for Minnesota, 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. 1484 wells filed a hardness value; 3065 had it computed from calcium + magnesium. 535 local cells, 29 counties. 2 counties dropped for straddling the softener threshold. A county appears only when at least 3 distinct wells carry a laboratory hardness result; the 58 of Minnesota’s 87 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) | mg/L CaCO3 | Rating | Wells | Samples |
|---|---|---|---|---|---|
| Anoka | 12.9 | 221 | very hard | 245 | 245 |
| Becker | 18.2 | 312 | very hard | 162 | 162 |
| Beltrami | 15.3 | 262 | very hard | 107 | 107 |
| Benton | 11.2 | 192 | very hard | 112 | 112 |
| Carver | 23.8 | 407 | very hard | 90 | 90 |
| Cass | 12.5 | 214 | very hard | 162 | 162 |
| Chippewa | 35.3 | 604 | very hard | 21 | 21 |
| Clearwater | 17.8 | 305 | very hard | 30 | 30 |
| Douglas | 21.2 | 363 | very hard | 75 | 75 |
| Hennepin | 22.6 | 387 | very hard | 370 | 370 |
| Hubbard | 14.3 | 245 | very hard | 186 | 186 |
| Isanti | 13.5 | 231 | very hard | 138 | 138 |
| Itasca | 12.5 | 214 | very hard | 96 | 96 |
| Kandiyohi | 21.6 | 370 | very hard | 121 | 121 |
| Mcleod | 22.8 | 390 | very hard | 85 | 85 |
| Meeker | 20.2 | 346 | very hard | 105 | 105 |
| Mille Lacs | 13.7 | 235 | very hard | 42 | 42 |
| Morrison | 12.9 | 221 | very hard | 184 | 184 |
| Otter Tail | 18.4 | 315 | very hard | 385 | 385 |
| Pope | 19.9 | 341 | very hard | 155 | 155 |
| Renville | 30.3 | 519 | very hard | 128 | 128 |
| Sherburne | 13.1 | 224 | very hard | 213 | 213 |
| Sibley | 26.7 | 457 | very hard | 108 | 108 |
| Stearns | 19.6 | 336 | very hard | 374 | 374 |
| Stevens | 31.8 | 544 | very hard | 48 | 48 |
| Swift | 22.9 | 392 | very hard | 56 | 56 |
| Todd | 19.5 | 334 | very hard | 128 | 128 |
| Wadena | 15.2 | 260 | very hard | 179 | 179 |
| Wright | 21.8 | 373 | very hard | 129 | 129 |
Yes — the median of 385 laboratory hardness samples from 385 measured wells in Otter Tail County is 18.4 grains per gallon (about 315 mg/L as CaCO3), which is “very hard” on the Water Quality Association scale. This is groundwater measured at other wells in the county, not a reading from any one property.
Yes — the median of 374 laboratory hardness samples from 374 measured wells in Stearns County is 19.6 grains per gallon (about 336 mg/L as CaCO3), which is “very hard” on the Water Quality Association scale. This is groundwater measured at other wells in the county, not a reading from any one property.
Yes — the median of 370 laboratory hardness samples from 370 measured wells in Hennepin County is 22.6 grains per gallon (about 387 mg/L as CaCO3), which is “very hard” on the Water Quality Association scale. This is groundwater measured at other wells in the county, not a reading from any one property.
Yes — the median of 245 laboratory hardness samples from 245 measured wells in Anoka County is 12.9 grains per gallon (about 221 mg/L as CaCO3), which is “very hard” on the Water Quality Association scale. This is groundwater measured at other wells in the county, not a reading from any one property.
Yes — the median of 213 laboratory hardness samples from 213 measured wells in Sherburne County is 13.1 grains per gallon (about 224 mg/L as CaCO3), which is “very hard” on the Water Quality Association scale. This is groundwater measured at other wells in the county, not a reading from any one property.
Yes — the median of 186 laboratory hardness samples from 186 measured wells in Hubbard County is 14.3 grains per gallon (about 245 mg/L as CaCO3), which is “very hard” on the Water Quality Association scale. This is groundwater measured at other wells in the county, not a reading from any one property.
Yes — the median of 184 laboratory hardness samples from 184 measured wells in Morrison County is 12.9 grains per gallon (about 221 mg/L as CaCO3), which is “very hard” on the Water Quality Association scale. This is groundwater measured at other wells in the county, not a reading from any one property.
Yes — the median of 179 laboratory hardness samples from 179 measured wells in Wadena County is 15.2 grains per gallon (about 260 mg/L as CaCO3), which is “very hard” on the Water Quality Association scale. This is groundwater measured at other wells in the county, not a reading from any one property.
Yes — the median of 162 laboratory hardness samples from 162 measured wells in Becker County is 18.2 grains per gallon (about 312 mg/L as CaCO3), which is “very hard” on the Water Quality Association scale. This is groundwater measured at other wells in the county, not a reading from any one property.
Yes — the median of 162 laboratory hardness samples from 162 measured wells in Cass County is 12.5 grains per gallon (about 214 mg/L as CaCO3), which is “very hard” on the Water Quality Association scale. 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 Minnesota? The new wells behind these figures are sold by territory — well water leads in Minnesota.
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.