How hard is the water in Montgomery County, MO?
10.1 grains per gallon
A softener is worth it here.
The median hardness measured in Montgomery County, MO is 173 mg/L as calcium carbonate, which is 10.1 gpg. That is hard on the USGS scale. It comes from 483 samples at 7 sites between 1990 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 8.1 and 12 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: medium (how it is measured).
What to do next
At 10.1 gpg a softener is worth getting, mainly to protect the water heater and cut soap use. Get at least two quotes, ask each installer what grain capacity they are fitting, and check it against the sizing table below. Because Montgomery 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 6.8 to 21.2 gpg
The softest single sample on record in Montgomery County was 117 mg/L and the hardest 363 mg/L, a 3-fold gap. The top quarter of sites read above 12 gpg and the bottom quarter below 8.1 gpg.
Wells 21.2 gpg, rivers and lakes 9.7 gpg
1 groundwater samples from 1 wells put the median at 363 mg/L. 482 surface samples from 6 sites put it at 165.5 mg/L. In Montgomery County the wells come out 11.5 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 221 lb of salt a year (6 bags of 40 lb, about $40), 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 $140 a year.
Sizing at 10.1 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 606 | 24,000 | 74 lb |
| 2 | 1,212 | 24,000 | 147 lb |
| 4 | 2,424 | 24,000 | 295 lb |
| 6 | 3,636 | 32,000 | 442 lb |
Montgomery County against the rest of Missouri
Among the 110 Missouri counties with data, Montgomery County is number 86 of 110 counting from the hardest. Across the whole country it is harder than 52% of counties.
Softest in Missouri: Livingston County at 4.1 gpg. Hardest: Reynolds County at 96.7 gpg. Closest to Montgomery County: Madison County (10.1), Wright County (10), Gasconade County (10.2).