How hard is the water in Otter Tail County, MN?
17.6 grains per gallon
A softener will pay its way here.
The median hardness measured in Otter Tail County, MN is 301 mg/L as calcium carbonate, which is 17.6 gpg. That is very hard on the USGS scale. It comes from 146 samples at 61 sites between 1991 and 2023, 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 15.5 and 21.1 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 17.6 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 0.1 to 27.2 gpg
The softest single sample on record in Otter Tail County was 1.6 mg/L and the hardest 465 mg/L, a 291-fold gap. The top quarter of sites read above 21.1 gpg and the bottom quarter below 15.5 gpg. So even here some sites draw water soft enough to need nothing at all.
Wells 17.6 gpg, rivers and lakes 12.3 gpg
146 groundwater samples from 61 wells put the median at 301 mg/L. 133 surface samples from 58 sites put it at 210 mg/L. In Otter Tail County the wells come out 5.3 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 24,000-grain unit covers a week between regenerations. Expect about 384 lb of salt a year (10 bags of 40 lb, about $69), 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 $169 a year.
Sizing at 17.6 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 1,056 | 24,000 | 128 lb |
| 2 | 2,112 | 24,000 | 257 lb |
| 4 | 4,224 | 32,000 | 514 lb |
| 6 | 6,336 | 48,000 | 771 lb |
Otter Tail County against the rest of Minnesota
Among the 87 Minnesota counties with data, Otter Tail County is number 39 of 87 counting from the hardest. Across the whole country it is harder than 78% of counties.
Softest in Minnesota: Lake County at 1.3 gpg. Hardest: Traverse County at 42.6 gpg. Closest to Otter Tail County: Freeborn County (17.5), Kittson County (17.5), Norman County (17.7).