How hard is the water in Clay County, MO?
31 grains per gallon
A softener will pay its way here.
The median hardness measured in Clay County, MO is 531 mg/L as calcium carbonate, which is 31 gpg. That is very hard on the USGS scale. It comes from 69 samples at 11 sites between 1998 and 2026, 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 28.2 and 32.4 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 31 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 18.9 to 33.3 gpg
The softest single sample on record in Clay County was 323 mg/L and the hardest 570 mg/L, a 2-fold gap. The top quarter of sites read above 32.4 gpg and the bottom quarter below 28.2 gpg.
What a softener would cost to run
For a household of 3, a 40,000-grain unit covers a week between regenerations. Expect about 677 lb of salt a year (17 bags of 40 lb, about $122), 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 $222 a year.
Sizing at 31 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 1,860 | 24,000 | 226 lb |
| 2 | 3,720 | 32,000 | 453 lb |
| 4 | 7,440 | 64,000 | 905 lb |
| 6 | 11,160 | 80,000 | 1,358 lb |
Clay County against the rest of Missouri
Among the 110 Missouri counties with data, Clay County is number 5 of 110 counting from the hardest. Across the whole country it is harder than 95% of counties.
Softest in Missouri: Livingston County at 4.1 gpg. Hardest: Reynolds County at 96.7 gpg. Closest to Clay County: Howard County (34.3), Jackson County (26.9), St. Francois County (35.2).