How hard is the water in Idaho County, ID?
5.5 grains per gallon
Optional: a softener helps, but plenty of homes skip it.
The median hardness measured in Idaho County, ID is 95 mg/L as calcium carbonate, which is 5.5 gpg. That is moderately hard on the USGS scale. It comes from 161 samples at 45 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 3.7 and 7.7 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 5.5 gpg this is your call. Look for white film on glasses and crust on the shower head: if you see little of either, you can live without one. If you do want one, a 24,000-grain unit is enough, so ask for that size rather than a bigger one. Because Idaho County straddles a decision line, check your own tap with a $10 test strip before you spend anything.
More on when a softener is not worth it.
From 0.3 to 16.7 gpg
The softest single sample on record in Idaho County was 5.4 mg/L and the hardest 285.5 mg/L, a 53-fold gap. The top quarter of sites read above 7.7 gpg and the bottom quarter below 3.7 gpg.
Wells 5.5 gpg, rivers and lakes 3.4 gpg
161 groundwater samples from 45 wells put the median at 94.5 mg/L. 80 surface samples from 8 sites put it at 58.5 mg/L. In Idaho County the wells come out 2.1 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 121 lb of salt a year (4 bags of 40 lb, about $22), 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 $122 a year.
Sizing at 5.5 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 330 | 24,000 | 40 lb |
| 2 | 660 | 24,000 | 80 lb |
| 4 | 1,320 | 24,000 | 161 lb |
| 6 | 1,980 | 24,000 | 241 lb |
Idaho County against the rest of Idaho
Among the 44 Idaho counties with data, Idaho County is number 36 of 44 counting from the hardest. Across the whole country it is harder than 33% of counties.
Softest in Idaho: Valley County at 1.3 gpg. Hardest: Caribou County at 23 gpg. Closest to Idaho County: Bonner County (5.8), Gem County (5.3), Kootenai County (5.9).