How hard is the water in Prairie County, MT?
24.4 grains per gallon
A softener will pay its way here.
The median hardness measured in Prairie County, MT is 418 mg/L as calcium carbonate, which is 24.4 gpg. That is very hard on the USGS scale. It comes from 37 samples at 16 sites between 1993 and 2018, drawn from every sampling site in the county, wells and surface water together.
How much it varies here
Half the sites came in between 11.3 and 34 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 24.4 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 7.5 to 274.0 gpg
The softest single sample on record in Prairie County was 129 mg/L and the hardest 4,690 mg/L, a 36-fold gap. The top quarter of sites read above 34 gpg and the bottom quarter below 11.3 gpg.
Wells 42.2 gpg, rivers and lakes 24.4 gpg
1 groundwater samples from 1 wells put the median at 722 mg/L. 35 surface samples from 14 sites put it at 417.5 mg/L. In Prairie County the wells come out 17.8 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 533 lb of salt a year (14 bags of 40 lb, about $96), 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 $196 a year.
Sizing at 24.4 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 1,464 | 24,000 | 178 lb |
| 2 | 2,928 | 24,000 | 356 lb |
| 4 | 5,856 | 48,000 | 712 lb |
| 6 | 8,784 | 64,000 | 1,069 lb |
Prairie County against the rest of Montana
Among the 56 Montana counties with data, Prairie County is number 18 of 56 counting from the hardest. Across the whole country it is harder than 91% of counties.
Softest in Montana: Lincoln County at 3.4 gpg. Hardest: Rosebud County at 138.9 gpg. Closest to Prairie County: Phillips County (24.2), Carter County (24), McCone County (23.1).