How hard is the water in Caribou County, ID?
23 grains per gallon
A softener will pay its way here.
The median hardness measured in Caribou County, ID is 394 mg/L as calcium carbonate, which is 23 gpg. That is very hard on the USGS scale. It comes from 189 samples at 46 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 15.4 and 30.8 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 23 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 4.3 to 75.9 gpg
The softest single sample on record in Caribou County was 74.2 mg/L and the hardest 1,300 mg/L, an 18-fold gap. The top quarter of sites read above 30.8 gpg and the bottom quarter below 15.4 gpg.
Wells 23 gpg, rivers and lakes 15.3 gpg
189 groundwater samples from 46 wells put the median at 393.5 mg/L. 505 surface samples from 30 sites put it at 262.5 mg/L. In Caribou County the wells come out 7.7 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 32,000-grain unit covers a week between regenerations. Expect about 502 lb of salt a year (13 bags of 40 lb, about $90), 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 $190 a year.
Sizing at 23 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 1,380 | 24,000 | 168 lb |
| 2 | 2,760 | 24,000 | 336 lb |
| 4 | 5,520 | 40,000 | 672 lb |
| 6 | 8,280 | 64,000 | 1,007 lb |
Caribou County against the rest of Idaho
Among the 44 Idaho counties with data, Caribou County is the hardest. Across the whole country it is harder than 89% of counties.
Softest in Idaho: Valley County at 1.3 gpg. Closest to Caribou County: Oneida County (18.6), Twin Falls County (18), Bear Lake County (17.3).