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Illinois Water Hardness

Across the 6 cities we track in Illinois, hardness ranges from 5.79–28 GPG, with 5 cities running hard or very hard, and 2 more cities don't publish a figure.

6 cities tracked. View the Illinois hardness map → · Is Illinois water safe to drink? →

Peoria

28 GPG · 450 ppm
Very Hard

Rockford

20.5 GPG · 350.6 ppm
Very Hard

Joliet

17.53 GPG · 300 ppm
Very Hard

Chicago

8.19 GPG · 140 ppm
Hard

Aurora

7.89 GPG · 135 ppm
Hard

Springfield

5.79 GPG · 99 ppm
Moderate

Cities with no published figure

These Illinois cities don't publish a hardness number (it isn't a regulated parameter), so they can't be ranked — but we still track them. See each page for how to check your own tap.

Elgin

Hardness not published
Not Published

Naperville

Hardness not published
Not Published