How hard is the water in Randolph County, MO?
56.5 grains per gallon
A softener will pay its way here.
The median hardness measured in Randolph County, MO is 968 mg/L as calcium carbonate, which is 56.5 gpg. That is very hard on the USGS scale. It comes from 358 samples at 28 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 18.8 and 100.1 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 56.5 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.
More on sizing a softener for your household.
From 9.0 to 170.6 gpg
The softest single sample on record in Randolph County was 154 mg/L and the hardest 2,920 mg/L, a 19-fold gap. The top quarter of sites read above 100.1 gpg and the bottom quarter below 18.8 gpg.
Wells 88.5 gpg, rivers and lakes 54.1 gpg
2 groundwater samples from 1 wells put the median at 1515 mg/L. 356 surface samples from 27 sites put it at 926 mg/L. In Randolph County the wells come out 34.4 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 80,000-grain unit covers a week between regenerations. Expect about 1,235 lb of salt a year (31 bags of 40 lb, about $222), 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 $322 a year.
Sizing at 56.5 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 3,390 | 24,000 | 412 lb |
| 2 | 6,780 | 48,000 | 825 lb |
| 4 | 13,560 | twin tank | 1,650 lb |
| 6 | 20,340 | twin tank | 2,475 lb |
Randolph County against the rest of Missouri
Among the 110 Missouri counties with data, Randolph County is number 2 of 110 counting from the hardest. Across the whole country it is harder than 98% of counties.
Softest in Missouri: Livingston County at 4.1 gpg. Hardest: Reynolds County at 96.7 gpg. Closest to Randolph County: St. Francois County (35.2), Howard County (34.3), Clay County (31).