How hard is the water in Watonwan County, MN?
19.9 grains per gallon
A softener will pay its way here.
The median hardness measured in Watonwan County, MN is 340 mg/L as calcium carbonate, which is 19.9 gpg. That is very hard on the USGS scale. It comes from 52 samples at 21 sites between 2013 and 2025, drawn from every sampling site in the county, wells and surface water together.
How much it varies here
Half the sites came in between 15.8 and 22.8 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: high (how it is measured).
What to do next
At 19.9 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 10.5 to 27.7 gpg
The softest single sample on record in Watonwan County was 180 mg/L and the hardest 475 mg/L, a 3-fold gap. The top quarter of sites read above 22.8 gpg and the bottom quarter below 15.8 gpg.
What a softener would cost to run
For a household of 3, a 32,000-grain unit covers a week between regenerations. Expect about 434 lb of salt a year (11 bags of 40 lb, about $78), 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 $178 a year.
Sizing at 19.9 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 1,194 | 24,000 | 145 lb |
| 2 | 2,388 | 24,000 | 291 lb |
| 4 | 4,776 | 40,000 | 581 lb |
| 6 | 7,164 | 64,000 | 872 lb |
Watonwan County against the rest of Minnesota
Among the 87 Minnesota counties with data, Watonwan County is number 26 of 87 counting from the hardest. Across the whole country it is harder than 84% of counties.
Softest in Minnesota: Lake County at 1.3 gpg. Hardest: Traverse County at 42.6 gpg. Closest to Watonwan County: Faribault County (19.9), Stearns County (19.7), Scott County (19.7).