How hard is the water in Cooper County, MO?
11 grains per gallon
A softener will pay its way here.
The median hardness measured in Cooper County, MO is 188 mg/L as calcium carbonate, which is 11 gpg. That is very hard on the USGS scale. It comes from 185 samples at 10 sites between 1999 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 9.7 and 12.2 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 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 Cooper 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 9.0 to 16.6 gpg
The softest single sample on record in Cooper County was 153.5 mg/L and the hardest 285 mg/L, a 2-fold gap. The top quarter of sites read above 12.2 gpg and the bottom quarter below 9.7 gpg.
Wells 16.6 gpg, rivers and lakes 10.9 gpg
1 groundwater samples from 1 wells put the median at 285 mg/L. 184 surface samples from 9 sites put it at 186 mg/L. In Cooper County the wells come out 5.7 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, a 24,000-grain unit covers a week between regenerations. Expect about 240 lb of salt a year (6 bags of 40 lb, about $43), 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 $143 a year.
Sizing at 11 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 660 | 24,000 | 80 lb |
| 2 | 1,320 | 24,000 | 161 lb |
| 4 | 2,640 | 24,000 | 321 lb |
| 6 | 3,960 | 32,000 | 482 lb |
Cooper County against the rest of Missouri
Among the 110 Missouri counties with data, Cooper County is number 73 of 110 counting from the hardest. Across the whole country it is harder than 54% of counties.
Softest in Missouri: Livingston County at 4.1 gpg. Hardest: Reynolds County at 96.7 gpg. Closest to Cooper County: Atchison County (11), Phelps County (11), Lafayette County (10.9).