Is Illinois tap water hard or soft?
Yes, mostly. 79 % of the 14 cities with published data in Illinois have hard or very hard water (over 120 mg/L). The median is 8 gpg, from 5.7 gpg in Springfield, IL to 28 gpg in East Peoria.
We have published hardness data for 14 cities in Illinois. The median is 8 gpg; the hardest water is in East Peoria (28 gpg), the softest in Springfield, IL (5.7 gpg).
79 % of these cities have hard or very hard water (over 120 mg/L).
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Cities in Illinois, hardest first
| gpg | mg/L | ||
|---|---|---|---|
| East Peoria | 28 | 479 | very hard |
| Rockford | 20.5 | 351 | very hard |
| Western Springs | 11.4 | 196 | very hard |
| Kankakee | 9.5 | 163 | hard |
| Elmhurst | 8.4 | 144 | hard |
| La Grange Park | 8 | 137 | hard |
| Palatine | 8 | 137 | hard |
| Wheaton | 7.9 | 136 | hard |
| Des Plaines | 7.9 | 136 | hard |
| Chicago | 7.9 | 135 | hard |
| Elgin | 7.5 | 128 | hard |
| DeKalb | 7 | 120 | moderately hard |
| Lake Zurich | 7 | 120 | moderately hard |
| Springfield, IL | 5.7 | 97 | moderately hard |
FAQ
Is Illinois water hard or soft?
Yes, mostly. 79 % of the 14 cities we cover have hard or very hard water; the median is 8 gpg.
Which city in Illinois has the hardest water?
East Peoria, at 28 gpg, has the hardest water of the 14 cities with published data.
Which city in Illinois has the softest water?
Springfield, IL, at 5.7 gpg, has the softest water of the 14 cities with published data.
Do I need a water softener in Illinois?
Above about 120 mg/L (7 gpg) scale builds up in water heaters, kettles and dishwashers, and a softener or at least regular descaling pays off. Look up your own city in the table: in Illinois the values range from 5.7 gpg to 28 gpg.
On a private well? Well water hardness in Illinois by county →