How hard is the water in Blue Earth County, MN?
27.6 grains per gallon
A softener will pay its way here.
The median hardness measured in Blue Earth County, MN is 473 mg/L as calcium carbonate, which is 27.6 gpg. That is very hard on the USGS scale. It comes from 13 samples at 13 sites between 1991 and 2025, drawn from groundwater wells, which is what most taps and private wells in the county draw on.
How much it varies here
Half the sites came in between 21.2 and 37.3 gpg. The whole middle of that range gives the same answer, so a test of your own tap is unlikely to change it. Confidence in the county figure: medium (how it is measured).
What to do next
At 27.6 gpg a softener pays its way here. Before you buy, check the quoted unit's grain capacity against the sizing table below, and ask whether it regenerates on demand, which uses less salt than a timer. Call your utility for its own report if you are on city water.
More on sizing a softener for your household.
From 18.9 to 53.6 gpg
The softest single sample on record in Blue Earth County was 323 mg/L and the hardest 917 mg/L, a 3-fold gap. The top quarter of sites read above 37.3 gpg and the bottom quarter below 21.2 gpg.
Wells 27.6 gpg, rivers and lakes 19.1 gpg
13 groundwater samples from 13 wells put the median at 473 mg/L. 417 surface samples from 45 sites put it at 327 mg/L. In Blue Earth County the wells come out 8.5 gpg harder. Groundwater sits in contact with rock for years and picks up calcium and magnesium as it goes, so wells usually read harder. A utility here that draws from the river can deliver noticeably different water from a private well next door.
What a softener would cost to run
For a household of 3, a 40,000-grain unit covers a week between regenerations. Expect about 603 lb of salt a year (16 bags of 40 lb, about $109), and roughly 2,346 gallons of regeneration water. Installed, most units run $1,000 to $4,500; spread over 15 years with salt, that is about $209 a year.
Sizing at 27.6 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 1,656 | 24,000 | 201 lb |
| 2 | 3,312 | 24,000 | 403 lb |
| 4 | 6,624 | 48,000 | 806 lb |
| 6 | 9,936 | 80,000 | 1,209 lb |
Blue Earth County against the rest of Minnesota
Among the 87 Minnesota counties with data, Blue Earth County is number 6 of 87 counting from the hardest. Across the whole country it is harder than 93% of counties.
Softest in Minnesota: Lake County at 1.3 gpg. Hardest: Traverse County at 42.6 gpg. Closest to Blue Earth County: Lincoln County (26.4), Chippewa County (26.3), Wilkin County (25.6).