How hard is the water in DuPage County, IL?
17.6 grains per gallon
A softener will pay its way here.
The median hardness measured in DuPage County, IL is 302 mg/L as calcium carbonate, which is 17.6 gpg. That is very hard on the USGS scale. It comes from 304 samples at 13 sites between 1990 and 2002, drawn from every sampling site in the county, wells and surface water together.
How much it varies here
Half the sites came in between 15.9 and 19.3 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 17.6 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 11.2 to 35.6 gpg
The softest single sample on record in DuPage County was 191 mg/L and the hardest 610 mg/L, a 3-fold gap. The top quarter of sites read above 19.3 gpg and the bottom quarter below 15.9 gpg.
Wells 28.5 gpg, rivers and lakes 17.5 gpg
21 groundwater samples from 4 wells put the median at 488 mg/L. 283 surface samples from 9 sites put it at 299 mg/L. In DuPage County the wells come out 11.0 gpg harder. Groundwater sits in contact with rock for years and picks up calcium and magnesium as it goes, so wells usually read harder. 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 385 lb of salt a year (10 bags of 40 lb, about $69), 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 $169 a year.
Sizing at 17.6 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 1,056 | 24,000 | 128 lb |
| 2 | 2,112 | 24,000 | 257 lb |
| 4 | 4,224 | 32,000 | 514 lb |
| 6 | 6,336 | 48,000 | 771 lb |
DuPage County against the rest of Illinois
Among the 102 Illinois counties with data, DuPage County is number 47 of 102 counting from the hardest. Across the whole country it is harder than 78% of counties.
Softest in Illinois: Pope County at 4.3 gpg. Hardest: Cook County at 34.8 gpg. Closest to DuPage County: Coles County (17.6), Mason County (17.5), Sangamon County (17.5).