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Illinois Water Hardness Map

6 cities · average 14.7 GPG

Average hardness

14.7 GPG

Hardest city

Peoria 28 GPG

Softest city

Springfield 5.79 GPG

Map — Illinois cities by hardness

Very HardHardModerateSoft

Tier distribution

Very Hard3Hard2Moderate1

Cities ranked by hardness

1Peoria28 GPGVery Hard2Rockford20.5 GPGVery Hard3Joliet17.53 GPGVery Hard4Chicago8.19 GPGHard5Aurora7.89 GPGHard6Springfield5.79 GPGModerate