How hard is the water in Lemhi County, ID?
8.6 grains per gallon
A softener is worth it here.
The median hardness measured in Lemhi County, ID is 147 mg/L as calcium carbonate, which is 8.6 gpg. That is hard on the USGS scale. It comes from 129 samples at 34 sites between 1990 and 2011, 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 5.8 and 11.6 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 8.6 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 Lemhi 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 1.9 to 59.9 gpg
The softest single sample on record in Lemhi County was 32.4 mg/L and the hardest 1,025 mg/L, a 32-fold gap. The top quarter of sites read above 11.6 gpg and the bottom quarter below 5.8 gpg. So even here some sites draw water soft enough to need nothing at all.
Wells 8.6 gpg, rivers and lakes 10.4 gpg
129 groundwater samples from 34 wells put the median at 147 mg/L. 36 surface samples from 3 sites put it at 177.5 mg/L. In Lemhi County the rivers and lakes come out 1.8 gpg harder. Here the surface water reads harder than the wells, which often points to streams fed by limestone springs or irrigation return flow. 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 188 lb of salt a year (5 bags of 40 lb, about $34), 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 $134 a year.
Sizing at 8.6 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 516 | 24,000 | 63 lb |
| 2 | 1,032 | 24,000 | 126 lb |
| 4 | 2,064 | 24,000 | 251 lb |
| 6 | 3,096 | 24,000 | 377 lb |
Lemhi County against the rest of Idaho
Among the 44 Idaho counties with data, Lemhi County is number 22 of 44 counting from the hardest. Across the whole country it is harder than 45% of counties.
Softest in Idaho: Valley County at 1.3 gpg. Hardest: Caribou County at 23 gpg. Closest to Lemhi County: Clark County (8.5), Custer County (8.5), Lincoln County (8.2).