How hard is the water in St. Francois County, MO?
35.2 grains per gallon
A softener will pay its way here.
The median hardness measured in St. Francois County, MO is 602 mg/L as calcium carbonate, which is 35.2 gpg. That is very hard on the USGS scale. It comes from 126 samples at 53 sites between 1990 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 27.2 and 46.4 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 35.2 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 11.0 to 109.2 gpg
The softest single sample on record in St. Francois County was 188 mg/L and the hardest 1,870 mg/L, a 10-fold gap. The top quarter of sites read above 46.4 gpg and the bottom quarter below 27.2 gpg.
Wells 35.2 gpg, rivers and lakes 17 gpg
126 groundwater samples from 53 wells put the median at 602 mg/L. 606 surface samples from 54 sites put it at 291 mg/L. In St. Francois County the wells come out 18.2 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 48,000-grain unit covers a week between regenerations. Expect about 768 lb of salt a year (20 bags of 40 lb, about $138), 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 $238 a year.
Sizing at 35.2 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 2,112 | 24,000 | 257 lb |
| 2 | 4,224 | 32,000 | 514 lb |
| 4 | 8,448 | 64,000 | 1,028 lb |
| 6 | 12,672 | twin tank | 1,542 lb |
St. Francois County against the rest of Missouri
Among the 110 Missouri counties with data, St. Francois County is number 3 of 110 counting from the hardest. Across the whole country it is harder than 96% of counties.
Softest in Missouri: Livingston County at 4.1 gpg. Hardest: Reynolds County at 96.7 gpg. Closest to St. Francois County: Howard County (34.3), Clay County (31), Jackson County (26.9).