How hard is the water in Dawson County, MT?
30.2 grains per gallon
A softener will pay its way here.
The median hardness measured in Dawson County, MT is 517 mg/L as calcium carbonate, which is 30.2 gpg. That is very hard on the USGS scale. It comes from 82 samples at 26 sites between 1994 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 18.4 and 44.7 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 30.2 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 0.9 to 172.6 gpg
The softest single sample on record in Dawson County was 14.9 mg/L and the hardest 2,955 mg/L, a 198-fold gap. The top quarter of sites read above 44.7 gpg and the bottom quarter below 18.4 gpg. So even here some sites draw water soft enough to need nothing at all.
Wells 11.6 gpg, rivers and lakes 32.1 gpg
3 groundwater samples from 2 wells put the median at 199.2 mg/L. 78 surface samples from 23 sites put it at 550 mg/L. In Dawson County the rivers and lakes come out 20.5 gpg harder. Here the surface water reads harder than the wells, which often points to streams fed by limestone springs or irrigation return flow. A utility here that draws from the aquifer can deliver noticeably different water from a private well next door.
What a softener would cost to run
For a household of 3, a 40,000-grain unit covers a week between regenerations. Expect about 660 lb of salt a year (17 bags of 40 lb, about $119), 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 $219 a year.
Sizing at 30.2 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 1,812 | 24,000 | 220 lb |
| 2 | 3,624 | 32,000 | 441 lb |
| 4 | 7,248 | 64,000 | 882 lb |
| 6 | 10,872 | 80,000 | 1,323 lb |
Dawson County against the rest of Montana
Among the 56 Montana counties with data, Dawson County is number 13 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 Dawson County: Wibaux County (30.8), Richland County (29.1), Fergus County (28.9).