How hard is the water in Caddo County, OK?
10.5 grains per gallon
A softener will pay its way here.
The median hardness measured in Caddo County, OK is 181 mg/L as calcium carbonate, which is 10.5 gpg. That is very hard on the USGS scale. It comes from 16 samples at 12 sites between 1990 and 2025, 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 7.4 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: medium (how it is measured).
What to do next
At 10.5 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 Caddo 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 4.2 to 17.2 gpg
The softest single sample on record in Caddo County was 71.3 mg/L and the hardest 294 mg/L, a 4-fold gap. The top quarter of sites read above 13.8 gpg and the bottom quarter below 7.4 gpg.
Wells 10.5 gpg, rivers and lakes 39.8 gpg
16 groundwater samples from 12 wells put the median at 180.5 mg/L. 626 surface samples from 28 sites put it at 680.5 mg/L. In Caddo County the rivers and lakes come out 29.3 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 24,000-grain unit covers a week between regenerations. Expect about 230 lb of salt a year (6 bags of 40 lb, about $41), 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 $141 a year.
Sizing at 10.5 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 630 | 24,000 | 77 lb |
| 2 | 1,260 | 24,000 | 153 lb |
| 4 | 2,520 | 24,000 | 307 lb |
| 6 | 3,780 | 32,000 | 460 lb |
Caddo County against the rest of Oklahoma
Among the 77 Oklahoma counties with data, Caddo County is number 53 of 77 counting from the hardest. Across the whole country it is harder than 53% of counties.
Softest in Oklahoma: McCurtain County at 0.8 gpg. Hardest: Greer County at 125 gpg. Closest to Caddo County: Bryan County (10.8), McIntosh County (11), Lincoln County (11.1).