How hard is the water in Park County, MT?
5.1 grains per gallon
Optional: a softener helps, but plenty of homes skip it.
The median hardness measured in Park County, MT is 88 mg/L as calcium carbonate, which is 5.1 gpg. That is moderately hard on the USGS scale. It comes from 94 samples at 44 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 2.2 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 5.1 gpg this is your call. Look for white film on glasses and crust on the shower head: if you see little of either, you can live without one. If you do want one, a 24,000-grain unit is enough, so ask for that size rather than a bigger one. Because Park County straddles a decision line, check your own tap with a $10 test strip before you spend anything.
More on when a softener is not worth it.
From 0.6 to 61.3 gpg
The softest single sample on record in Park County was 10.3 mg/L and the hardest 1,050 mg/L, a 102-fold gap. The top quarter of sites read above 13.8 gpg and the bottom quarter below 2.2 gpg.
Wells 5.1 gpg, rivers and lakes 4.7 gpg
94 groundwater samples from 44 wells put the median at 88.1 mg/L. 747 surface samples from 206 sites put it at 80.4 mg/L. In Park County the wells come out 0.4 gpg harder. Groundwater sits in contact with rock for years and picks up calcium and magnesium as it goes, so wells usually read harder. 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 112 lb of salt a year (3 bags of 40 lb, about $20), 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 $120 a year.
Sizing at 5.1 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 306 | 24,000 | 37 lb |
| 2 | 612 | 24,000 | 74 lb |
| 4 | 1,224 | 24,000 | 149 lb |
| 6 | 1,836 | 24,000 | 223 lb |
Park County against the rest of Montana
Among the 56 Montana counties with data, Park County is number 51 of 56 counting from the hardest. Across the whole country it is harder than 31% of counties.
Softest in Montana: Lincoln County at 3.4 gpg. Hardest: Rosebud County at 138.9 gpg. Closest to Park County: Sweet Grass County (5), Ravalli County (4.6), Mineral County (4.5).