How hard is the water in Dewey County, OK?
116.4 grains per gallon
A softener will pay its way here.
The median hardness measured in Dewey County, OK is 1992 mg/L as calcium carbonate, which is 116.4 gpg. That is very hard on the USGS scale. It comes from 192 samples at 9 sites between 1990 and 2023, drawn from every sampling site in the county, wells and surface water together.
How much it varies here
Half the sites came in between 112.2 and 129.3 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: medium (how it is measured).
What to do next
At 116.4 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 48.5 to 164.6 gpg
The softest single sample on record in Dewey County was 830 mg/L and the hardest 2,817 mg/L, a 3-fold gap. The top quarter of sites read above 129.3 gpg and the bottom quarter below 112.2 gpg.
Wells 134.4 gpg, rivers and lakes 116.3 gpg
1 groundwater samples from 1 wells put the median at 2300 mg/L. 191 surface samples from 8 sites put it at 1991.6 mg/L. In Dewey County the wells come out 18.1 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, the water is harder than a standard single tank handles in a week, so plan on a larger or twin-tank unit. Expect about 2,541 lb of salt a year (64 bags of 40 lb, about $457), 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 $557 a year.
Sizing at 116.4 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 6,984 | 64,000 | 850 lb |
| 2 | 13,968 | twin tank | 1,699 lb |
| 4 | 27,936 | twin tank | 3,399 lb |
| 6 | 41,904 | twin tank | 5,098 lb |
Dewey County against the rest of Oklahoma
Among the 77 Oklahoma counties with data, Dewey County is number 3 of 77 counting from the hardest. Across the whole country it is harder than 99% of counties.
Softest in Oklahoma: McCurtain County at 0.8 gpg. Hardest: Greer County at 125 gpg. Closest to Dewey County: Custer County (115.8), Woods County (115.7), Harmon County (120.9).