How hard is the water in McDonough County, IL?
20.6 grains per gallon
A softener will pay its way here.
The median hardness measured in McDonough County, IL is 353 mg/L as calcium carbonate, which is 20.6 gpg. That is very hard on the USGS scale. It comes from 6 samples at 5 sites between 1990 and 2017, 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 17.2 and 23.9 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: medium (how it is measured).
What to do next
At 20.6 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 14.9 to 24.8 gpg
The softest single sample on record in McDonough County was 255 mg/L and the hardest 425 mg/L, a 2-fold gap. The top quarter of sites read above 23.9 gpg and the bottom quarter below 17.2 gpg.
Wells 20.6 gpg, rivers and lakes 14.3 gpg
6 groundwater samples from 5 wells put the median at 353 mg/L. 199 surface samples from 11 sites put it at 244 mg/L. In McDonough County the wells come out 6.3 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 450 lb of salt a year (12 bags of 40 lb, about $81), 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 $181 a year.
Sizing at 20.6 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 1,236 | 24,000 | 150 lb |
| 2 | 2,472 | 24,000 | 301 lb |
| 4 | 4,944 | 40,000 | 602 lb |
| 6 | 7,416 | 64,000 | 902 lb |
McDonough County against the rest of Illinois
Among the 102 Illinois counties with data, McDonough County is number 25 of 102 counting from the hardest. Across the whole country it is harder than 85% of counties.
Softest in Illinois: Pope County at 4.3 gpg. Hardest: Cook County at 34.8 gpg. Closest to McDonough County: Fulton County (20.6), Jo Daviess County (20.7), Boone County (20.7).