How hard is the water in Big Horn County, MT?
32.1 grains per gallon
A softener will pay its way here.
The median hardness measured in Big Horn County, MT is 550 mg/L as calcium carbonate, which is 32.1 gpg. That is very hard on the USGS scale. It comes from 68 samples at 60 sites between 1990 and 2026, 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 9.7 and 49 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 32.1 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 Big Horn 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 0.2 to 182.3 gpg
The softest single sample on record in Big Horn County was 2.7 mg/L and the hardest 3,120 mg/L, a 1,156-fold gap. The top quarter of sites read above 49 gpg and the bottom quarter below 9.7 gpg. So even here some sites draw water soft enough to need nothing at all.
Wells 32.1 gpg, rivers and lakes 20.4 gpg
68 groundwater samples from 60 wells put the median at 550 mg/L. 827 surface samples from 43 sites put it at 349.5 mg/L. In Big Horn County the wells come out 11.7 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 48,000-grain unit covers a week between regenerations. Expect about 702 lb of salt a year (18 bags of 40 lb, about $126), 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 $226 a year.
Sizing at 32.1 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 1,926 | 24,000 | 234 lb |
| 2 | 3,852 | 32,000 | 469 lb |
| 4 | 7,704 | 64,000 | 937 lb |
| 6 | 11,556 | twin tank | 1,406 lb |
Big Horn County against the rest of Montana
Among the 56 Montana counties with data, Big Horn County is number 11 of 56 counting from the hardest. Across the whole country it is harder than 95% of counties.
Softest in Montana: Lincoln County at 3.4 gpg. Hardest: Rosebud County at 138.9 gpg. Closest to Big Horn County: Wibaux County (30.8), Dawson County (30.2), Richland County (29.1).