How hard is the water in McHenry County, IL?
23.2 grains per gallon
A softener will pay its way here.
The median hardness measured in McHenry County, IL is 398 mg/L as calcium carbonate, which is 23.2 gpg. That is very hard on the USGS scale. It comes from 204 samples at 78 sites between 1990 and 2021, 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 18.8 and 26.6 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 23.2 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 8.2 to 39.0 gpg
The softest single sample on record in McHenry County was 141 mg/L and the hardest 668 mg/L, a 5-fold gap. The top quarter of sites read above 26.6 gpg and the bottom quarter below 18.8 gpg.
Wells 23.2 gpg, rivers and lakes 22.2 gpg
204 groundwater samples from 78 wells put the median at 397.5 mg/L. 428 surface samples from 30 sites put it at 380 mg/L. In McHenry County the wells come out 1.0 gpg harder. Groundwater sits in contact with rock for years and picks up calcium and magnesium as it goes, so wells usually read harder. The two sources are close, so the county figure should hold whichever one your tap is on.
What a softener would cost to run
For a household of 3, a 32,000-grain unit covers a week between regenerations. Expect about 507 lb of salt a year (13 bags of 40 lb, about $91), 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 $191 a year.
Sizing at 23.2 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 1,392 | 24,000 | 169 lb |
| 2 | 2,784 | 24,000 | 339 lb |
| 4 | 5,568 | 40,000 | 677 lb |
| 6 | 8,352 | 64,000 | 1,016 lb |
McHenry County against the rest of Illinois
Among the 102 Illinois counties with data, McHenry County is number 9 of 102 counting from the hardest. Across the whole country it is harder than 90% of counties.
Softest in Illinois: Pope County at 4.3 gpg. Hardest: Cook County at 34.8 gpg. Closest to McHenry County: Lake County (23.4), McLean County (23.4), LaSalle County (22.7).