How hard is the water in Jefferson County, ID?
11.1 grains per gallon
A softener will pay its way here.
The median hardness measured in Jefferson County, ID is 190 mg/L as calcium carbonate, which is 11.1 gpg. That is very hard on the USGS scale. It comes from 257 samples at 76 sites between 1990 and 2018, 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 7.5 and 13.8 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 11.1 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. Because Jefferson 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 4.3 to 59.0 gpg
The softest single sample on record in Jefferson County was 74 mg/L and the hardest 1,009.5 mg/L, a 14-fold gap. The top quarter of sites read above 13.8 gpg and the bottom quarter below 7.5 gpg.
Wells 11.1 gpg, rivers and lakes 7.5 gpg
257 groundwater samples from 76 wells put the median at 189.5 mg/L. 12 surface samples from 2 sites put it at 129.1 mg/L. In Jefferson County the wells come out 3.6 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 24,000-grain unit covers a week between regenerations. Expect about 242 lb of salt a year (7 bags of 40 lb, about $44), 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 $144 a year.
Sizing at 11.1 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 666 | 24,000 | 81 lb |
| 2 | 1,332 | 24,000 | 162 lb |
| 4 | 2,664 | 24,000 | 324 lb |
| 6 | 3,996 | 32,000 | 486 lb |
Jefferson County against the rest of Idaho
Among the 44 Idaho counties with data, Jefferson County is number 15 of 44 counting from the hardest. Across the whole country it is harder than 55% of counties.
Softest in Idaho: Valley County at 1.3 gpg. Hardest: Caribou County at 23 gpg. Closest to Jefferson County: Payette County (11.3), Teton County (10.9), Canyon County (10.7).