How hard is the water in Franklin County, ID?
16.3 grains per gallon
A softener will pay its way here.
The median hardness measured in Franklin County, ID is 279 mg/L as calcium carbonate, which is 16.3 gpg. That is very hard on the USGS scale. It comes from 66 samples at 21 sites between 1990 and 2015, 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 11.7 and 18.9 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 16.3 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 1.3 to 34.2 gpg
The softest single sample on record in Franklin County was 21.6 mg/L and the hardest 585 mg/L, a 27-fold gap. The top quarter of sites read above 18.9 gpg and the bottom quarter below 11.7 gpg. So even here some sites draw water soft enough to need nothing at all.
Wells 16.3 gpg, rivers and lakes 18.4 gpg
66 groundwater samples from 21 wells put the median at 279 mg/L. 618 surface samples from 26 sites put it at 315 mg/L. In Franklin County the rivers and lakes come out 2.1 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 356 lb of salt a year (9 bags of 40 lb, about $64), 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 $164 a year.
Sizing at 16.3 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 978 | 24,000 | 119 lb |
| 2 | 1,956 | 24,000 | 238 lb |
| 4 | 3,912 | 32,000 | 476 lb |
| 6 | 5,868 | 48,000 | 714 lb |
Franklin County against the rest of Idaho
Among the 44 Idaho counties with data, Franklin County is number 5 of 44 counting from the hardest. Across the whole country it is harder than 73% of counties.
Softest in Idaho: Valley County at 1.3 gpg. Hardest: Caribou County at 23 gpg. Closest to Franklin County: Minidoka County (16.1), Bannock County (15.5), Bear Lake County (17.3).