How hard is the water in Stanley County, SD?

16.1 grains per gallon

A softener will pay its way here.

The median hardness measured in Stanley County, SD is 275 mg/L as calcium carbonate, which is 16.1 gpg. That is very hard on the USGS scale. It comes from 46 samples at 3 sites between 1991 and 2014, drawn from every sampling site in the county, wells and surface water together.

How much it varies here

Half the sites came in between 16.1 and 31.5 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 16.1 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 16.1 to 46.9 gpg

The softest single sample on record in Stanley County was 275 mg/L and the hardest 803 mg/L, a 3-fold gap. The top quarter of sites read above 31.5 gpg and the bottom quarter below 16.1 gpg.

What a softener would cost to run

For a household of 3, a 24,000-grain unit covers a week between regenerations. Expect about 351 lb of salt a year (9 bags of 40 lb, about $63), 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 $163 a year.

Sizing at 16.1 gpg

Stanley County against the rest of South Dakota

Among the 55 South Dakota counties with data, Stanley County is number 38 of 55 counting from the hardest. Across the whole country it is harder than 73% of counties.

Softest in South Dakota: Dewey County at 0.5 gpg. Hardest: Hanson County at 84.7 gpg. Closest to Stanley County: Hughes County (16.4), Custer County (15.5), Perkins County (15.1).