How hard is the water in Tillman County, OK?
52 grains per gallon
A softener will pay its way here.
The median hardness measured in Tillman County, OK is 890 mg/L as calcium carbonate, which is 52 gpg. That is very hard on the USGS scale. It comes from 273 samples at 13 sites between 1990 and 2025, drawn from every sampling site in the county, wells and surface water together.
How much it varies here
Half the sites came in between 28.4 and 55.5 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 52 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 10.4 to 139.0 gpg
The softest single sample on record in Tillman County was 178 mg/L and the hardest 2,380 mg/L, a 13-fold gap. The top quarter of sites read above 55.5 gpg and the bottom quarter below 28.4 gpg.
What a softener would cost to run
For a household of 3, a 80,000-grain unit covers a week between regenerations. Expect about 1,135 lb of salt a year (29 bags of 40 lb, about $204), 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 $304 a year.
Sizing at 52 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 3,120 | 24,000 | 380 lb |
| 2 | 6,240 | 48,000 | 759 lb |
| 4 | 12,480 | twin tank | 1,518 lb |
| 6 | 18,720 | twin tank | 2,278 lb |
Tillman County against the rest of Oklahoma
Among the 77 Oklahoma counties with data, Tillman County is number 10 of 77 counting from the hardest. Across the whole country it is harder than 98% of counties.
Softest in Oklahoma: McCurtain County at 0.8 gpg. Hardest: Greer County at 125 gpg. Closest to Tillman County: Kiowa County (43.8), Beckham County (41), Washita County (64.8).