How hard is the water in Roosevelt County, MT?
49.5 grains per gallon
A softener will pay its way here.
The median hardness measured in Roosevelt County, MT is 847 mg/L as calcium carbonate, which is 49.5 gpg. That is very hard on the USGS scale. It comes from 184 samples at 128 sites between 1990 and 2021, 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 20.4 and 127.2 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 49.5 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 1.6 to 269.9 gpg
The softest single sample on record in Roosevelt County was 27 mg/L and the hardest 4,620 mg/L, a 171-fold gap. The top quarter of sites read above 127.2 gpg and the bottom quarter below 20.4 gpg. So even here some sites draw water soft enough to need nothing at all.
Wells 49.5 gpg, rivers and lakes 14.1 gpg
184 groundwater samples from 128 wells put the median at 847 mg/L. 129 surface samples from 15 sites put it at 242 mg/L. In Roosevelt County the wells come out 35.4 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 64,000-grain unit covers a week between regenerations. Expect about 1,081 lb of salt a year (28 bags of 40 lb, about $195), 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 $295 a year.
Sizing at 49.5 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 2,970 | 24,000 | 361 lb |
| 2 | 5,940 | 48,000 | 723 lb |
| 4 | 11,880 | twin tank | 1,445 lb |
| 6 | 17,820 | twin tank | 2,168 lb |
Roosevelt County against the rest of Montana
Among the 56 Montana counties with data, Roosevelt County is number 7 of 56 counting from the hardest. Across the whole country it is harder than 98% of counties.
Softest in Montana: Lincoln County at 3.4 gpg. Hardest: Rosebud County at 138.9 gpg. Closest to Roosevelt County: Petroleum County (50.9), Cascade County (58.6), Powder River County (60.8).