How hard is the water in Todd County, SD?
8.3 grains per gallon
A softener is worth it here.
The median hardness measured in Todd County, SD is 142 mg/L as calcium carbonate, which is 8.3 gpg. That is hard on the USGS scale. It comes from 122 samples at 115 sites between 1990 and 2016, 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 5.7 and 9.6 gpg. That spread crosses a decision line, so some homes here land on a different answer. A $10 test strip on your own tap settles it. Confidence in the county figure: high (how it is measured).
What to do next
At 8.3 gpg a softener is worth getting, mainly to protect the water heater and cut soap use. Get at least two quotes, ask each installer what grain capacity they are fitting, and check it against the sizing table below. Because Todd County straddles a decision line, check your own tap with a $10 test strip before you spend anything.
More on sizing a softener for your household.
From 0.6 to 37.8 gpg
The softest single sample on record in Todd County was 10 mg/L and the hardest 647 mg/L, a 65-fold gap. The top quarter of sites read above 9.6 gpg and the bottom quarter below 5.7 gpg. So even here some sites draw water soft enough to need nothing at all.
Wells 8.3 gpg, rivers and lakes 6.4 gpg
122 groundwater samples from 115 wells put the median at 142 mg/L. 57 surface samples from 13 sites put it at 109.5 mg/L. In Todd County the wells come out 1.9 gpg harder. Groundwater sits in contact with rock for years and picks up calcium and magnesium as it goes, so wells usually read harder. The two sources are close, so the county figure should hold whichever one your tap is on.
What a softener would cost to run
For a household of 3, a 24,000-grain unit covers a week between regenerations. Expect about 181 lb of salt a year (5 bags of 40 lb, about $33), 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 $133 a year.
Sizing at 8.3 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 498 | 24,000 | 61 lb |
| 2 | 996 | 24,000 | 121 lb |
| 4 | 1,992 | 24,000 | 242 lb |
| 6 | 2,988 | 24,000 | 364 lb |
Todd County against the rest of South Dakota
Among the 55 South Dakota counties with data, Todd County is number 49 of 55 counting from the hardest. Across the whole country it is harder than 44% of counties.
Softest in South Dakota: Dewey County at 0.5 gpg. Hardest: Hanson County at 84.7 gpg. Closest to Todd County: Oglala Lakota County (8.2), Tripp County (9.9), Beadle County (10.5).