How hard is the water in Marion County, OH?
19.3 grains per gallon
A softener will pay its way here.
The median hardness measured in Marion County, OH is 331 mg/L as calcium carbonate, which is 19.3 gpg. That is very hard on the USGS scale. It comes from 885 samples at 74 sites between 1995 and 2024, drawn from every sampling site in the county, wells and surface water together.
How much it varies here
Half the sites came in between 16.7 and 21.8 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 19.3 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 10.5 to 33.8 gpg
The softest single sample on record in Marion County was 180 mg/L and the hardest 578 mg/L, a 3-fold gap. The top quarter of sites read above 21.8 gpg and the bottom quarter below 16.7 gpg.
Wells 33.5 gpg, rivers and lakes 19.2 gpg
8 groundwater samples from 3 wells put the median at 574 mg/L. 807 surface samples from 67 sites put it at 329 mg/L. In Marion County the wells come out 14.3 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 422 lb of salt a year (11 bags of 40 lb, about $76), 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 $176 a year.
Sizing at 19.3 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 1,158 | 24,000 | 141 lb |
| 2 | 2,316 | 24,000 | 282 lb |
| 4 | 4,632 | 40,000 | 564 lb |
| 6 | 6,948 | 64,000 | 845 lb |
Marion County against the rest of Ohio
Among the 88 Ohio counties with data, Marion County is number 34 of 88 counting from the hardest. Across the whole country it is harder than 82% of counties.
Softest in Ohio: Scioto County at 5.7 gpg. Hardest: Perry County at 113.3 gpg. Closest to Marion County: Auglaize County (19.3), Seneca County (19.1), Washington County (19.1).