How hard is the water in Miami County, OH?
23.9 grains per gallon
A softener will pay its way here.
The median hardness measured in Miami County, OH is 409 mg/L as calcium carbonate, which is 23.9 gpg. That is very hard on the USGS scale. It comes from 62 samples at 21 sites between 1990 and 2024, 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 19.6 and 26.3 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 23.9 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 0.0 to 30.2 gpg
The softest single sample on record in Miami County was 0.3 mg/L and the hardest 517 mg/L, a 1,723-fold gap. The top quarter of sites read above 26.3 gpg and the bottom quarter below 19.6 gpg. So even here some sites draw water soft enough to need nothing at all.
Wells 23.9 gpg, rivers and lakes 18.1 gpg
62 groundwater samples from 21 wells put the median at 409 mg/L. 906 surface samples from 93 sites put it at 309 mg/L. In Miami County the wells come out 5.8 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 32,000-grain unit covers a week between regenerations. Expect about 522 lb of salt a year (14 bags of 40 lb, about $94), 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 $194 a year.
Sizing at 23.9 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 1,434 | 24,000 | 174 lb |
| 2 | 2,868 | 24,000 | 349 lb |
| 4 | 5,736 | 48,000 | 698 lb |
| 6 | 8,604 | 64,000 | 1,047 lb |
Miami County against the rest of Ohio
Among the 88 Ohio counties with data, Miami County is number 9 of 88 counting from the hardest. Across the whole country it is harder than 91% of counties.
Softest in Ohio: Scioto County at 5.7 gpg. Hardest: Perry County at 113.3 gpg. Closest to Miami County: Darke County (23.7), Fairfield County (23.5), Pickaway County (23.4).