How hard is the water in Lyman County, SD?
40.3 grains per gallon
A softener will pay its way here.
The median hardness measured in Lyman County, SD is 690 mg/L as calcium carbonate, which is 40.3 gpg. That is very hard on the USGS scale. It comes from 18 samples at 18 sites between 1990 and 2020, 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 18.7 and 75.9 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 40.3 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 7.6 to 87.6 gpg
The softest single sample on record in Lyman County was 130 mg/L and the hardest 1,500 mg/L, a 12-fold gap. The top quarter of sites read above 75.9 gpg and the bottom quarter below 18.7 gpg.
Wells 40.3 gpg, rivers and lakes 12.9 gpg
18 groundwater samples from 18 wells put the median at 690 mg/L. 276 surface samples from 15 sites put it at 220 mg/L. In Lyman County the wells come out 27.4 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 64,000-grain unit covers a week between regenerations. Expect about 880 lb of salt a year (23 bags of 40 lb, about $158), 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 $258 a year.
Sizing at 40.3 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 2,418 | 24,000 | 294 lb |
| 2 | 4,836 | 40,000 | 588 lb |
| 4 | 9,672 | 80,000 | 1,177 lb |
| 6 | 14,508 | twin tank | 1,765 lb |
Lyman County against the rest of South Dakota
Among the 55 South Dakota counties with data, Lyman County is number 11 of 55 counting from the hardest. Across the whole country it is harder than 97% of counties.
Softest in South Dakota: Dewey County at 0.5 gpg. Hardest: Hanson County at 84.7 gpg. Closest to Lyman County: Marshall County (38.4), Roberts County (38), Buffalo County (35.3).