How hard is the water in Grant County, SD?
25.3 grains per gallon
A softener will pay its way here.
The median hardness measured in Grant County, SD is 434 mg/L as calcium carbonate, which is 25.3 gpg. That is very hard on the USGS scale. It comes from 78 samples at 8 sites between 1997 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 22 and 29.8 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: medium (how it is measured).
What to do next
At 25.3 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 18.3 to 33.9 gpg
The softest single sample on record in Grant County was 314 mg/L and the hardest 580 mg/L, a 2-fold gap. The top quarter of sites read above 29.8 gpg and the bottom quarter below 22 gpg.
Wells 22.3 gpg, rivers and lakes 26.1 gpg
1 groundwater samples from 1 wells put the median at 381 mg/L. 77 surface samples from 7 sites put it at 447.5 mg/L. In Grant County the rivers and lakes come out 3.8 gpg harder. Here the surface water reads harder than the wells, which often points to streams fed by limestone springs or irrigation return flow. A utility here that draws from the aquifer can deliver noticeably different water from a private well next door.
What a softener would cost to run
For a household of 3, a 32,000-grain unit covers a week between regenerations. Expect about 553 lb of salt a year (14 bags of 40 lb, about $100), 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 $200 a year.
Sizing at 25.3 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 1,518 | 24,000 | 185 lb |
| 2 | 3,036 | 24,000 | 369 lb |
| 4 | 6,072 | 48,000 | 739 lb |
| 6 | 9,108 | 64,000 | 1,108 lb |
Grant County against the rest of South Dakota
Among the 55 South Dakota counties with data, Grant County is number 26 of 55 counting from the hardest. Across the whole country it is harder than 92% of counties.
Softest in South Dakota: Dewey County at 0.5 gpg. Hardest: Hanson County at 84.7 gpg. Closest to Grant County: Meade County (25.5), Aurora County (25.1), Fall River County (24.8).