How hard is the water in Ottawa County, OK?
11.5 grains per gallon
A softener will pay its way here.
The median hardness measured in Ottawa County, OK is 198 mg/L as calcium carbonate, which is 11.5 gpg. That is very hard on the USGS scale. It comes from 103 samples at 35 sites between 1990 and 2023, 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 8 and 23.3 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 11.5 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. Because Ottawa County straddles a decision line, check your own tap with a $10 test strip before you spend anything.
More on sizing a softener for your household.
From 5.2 to 92.9 gpg
The softest single sample on record in Ottawa County was 88.6 mg/L and the hardest 1,590 mg/L, an 18-fold gap. The top quarter of sites read above 23.3 gpg and the bottom quarter below 8 gpg.
Wells 11.5 gpg, rivers and lakes 10 gpg
103 groundwater samples from 35 wells put the median at 197.5 mg/L. 779 surface samples from 44 sites put it at 171 mg/L. In Ottawa County the wells come out 1.5 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 252 lb of salt a year (7 bags of 40 lb, about $45), 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 $145 a year.
Sizing at 11.5 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 690 | 24,000 | 84 lb |
| 2 | 1,380 | 24,000 | 168 lb |
| 4 | 2,760 | 24,000 | 336 lb |
| 6 | 4,140 | 32,000 | 504 lb |
Ottawa County against the rest of Oklahoma
Among the 77 Oklahoma counties with data, Ottawa County is number 48 of 77 counting from the hardest. Across the whole country it is harder than 57% of counties.
Softest in Oklahoma: McCurtain County at 0.8 gpg. Hardest: Greer County at 125 gpg. Closest to Ottawa County: Oklahoma County (11.8), Hughes County (11.2), Nowata County (12).