How hard is the water in Warren County, MO?

13.3 grains per gallon

A softener will pay its way here.

The median hardness measured in Warren County, MO is 228 mg/L as calcium carbonate, which is 13.3 gpg. That is very hard on the USGS scale. It comes from 74 samples at 10 sites between 2004 and 2026, drawn from every sampling site in the county, wells and surface water together.

How much it varies here

Half the sites came in between 11.1 and 13.6 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 13.3 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 8.9 to 15.9 gpg

The softest single sample on record in Warren County was 152 mg/L and the hardest 273 mg/L, a 2-fold gap. The top quarter of sites read above 13.6 gpg and the bottom quarter below 11.1 gpg.

What a softener would cost to run

For a household of 3, a 24,000-grain unit covers a week between regenerations. Expect about 290 lb of salt a year (8 bags of 40 lb, about $52), 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 $152 a year.

Sizing at 13.3 gpg

Warren County against the rest of Missouri

Among the 110 Missouri counties with data, Warren County is number 30 of 110 counting from the hardest. Across the whole country it is harder than 63% of counties.

Softest in Missouri: Livingston County at 4.1 gpg. Hardest: Reynolds County at 96.7 gpg. Closest to Warren County: Carter County (13.3), DeKalb County (13.4), Oregon County (13.4).