How hard is the water in Spink County, SD?
26.9 grains per gallon
A softener will pay its way here.
The median hardness measured in Spink County, SD is 460 mg/L as calcium carbonate, which is 26.9 gpg. That is very hard on the USGS scale. It comes from 70 samples at 64 sites between 1990 and 2014, 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 15.4 and 47.3 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: high (how it is measured).
What to do next
At 26.9 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 3.0 to 186.9 gpg
The softest single sample on record in Spink County was 51 mg/L and the hardest 3,200 mg/L, a 63-fold gap. The top quarter of sites read above 47.3 gpg and the bottom quarter below 15.4 gpg. So even here some sites draw water soft enough to need nothing at all.
Wells 26.9 gpg, rivers and lakes 33.3 gpg
70 groundwater samples from 64 wells put the median at 460 mg/L. 164 surface samples from 9 sites put it at 570 mg/L. In Spink County the rivers and lakes come out 6.4 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 40,000-grain unit covers a week between regenerations. Expect about 587 lb of salt a year (15 bags of 40 lb, about $106), 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 $206 a year.
Sizing at 26.9 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 1,614 | 24,000 | 196 lb |
| 2 | 3,228 | 24,000 | 393 lb |
| 4 | 6,456 | 48,000 | 785 lb |
| 6 | 9,684 | 80,000 | 1,178 lb |
Spink County against the rest of South Dakota
Among the 55 South Dakota counties with data, Spink County is number 23 of 55 counting from the hardest. Across the whole country it is harder than 93% of counties.
Softest in South Dakota: Dewey County at 0.5 gpg. Hardest: Hanson County at 84.7 gpg. Closest to Spink County: Minnehaha County (26), Campbell County (27.8), Brookings County (27.9).