Water quality · IL
Illinois Water Quality (2026)
Last updated: June 2026
Lake Michigan supplies most of northern Illinois with soft–moderate water; lead service lines remain a concern in older Chicago-area homes.
Our Illinois coverage focuses on the 5 metros below. Each city page lists the utility's water source, hardness in grains per gallon, contaminants flagged above EWG's stricter health guideline, and the whole-house system that fits that specific profile, not a generic recommendation copied across the state.
Common contaminants flagged across Illinois
Across the Illinois cities we cover, these are the contaminants most often reported above EWG's health guideline. None exceed federal EPA legal limits.
- radium
- lead service lines (older homes)
- Lead from legacy lead service lines in older homes
- radium (groundwater)
- disinfection byproducts
Cities we cover in Illinois
| City | Hardness | Flagged above EWG guideline | Best fit |
|---|---|---|---|
| Aurora | - | radium, lead service lines (older homes) | Softener + POU RO / lead filter |
| Chicago | ~8 (moderately hard) | Lead from legacy lead service lines in older homes | Lead-certified point-of-use filter + whole-house carbon |
| Naperville | - | lead service lines (older homes) | Carbon + POU RO / lead filter |
| Rockford | - | radium (groundwater) | Softener + POU RO |
| Springfield | - | disinfection byproducts | Softener + carbon |
Recommended systems for Illinois
Most Illinois homes benefit from a layered setup: whole-house carbon for chlorine and taste, a softener if your CCR shows hardness above 7 gpg, and a certified under-sink RO at the kitchen tap if lead, PFAS, nitrate or arsenic are flagged.
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Find your system →Illinois water FAQ
+Is Illinois tap water safe to drink?
Yes, by federal standards: the cities on this page all meet every EPA legal limit. The contaminants we flag sit above EWG's stricter, non-enforceable health guideline, which is the benchmark most homeowners use when deciding whether to filter further at home.
+Why is Illinois water hard?
Hardness comes from calcium and magnesium picked up as water moves through local geology. In Illinois, the values vary city by city, see the table above for your metro. Anything above 7 grains per gallon is considered hard and is where a softener starts to make a noticeable difference.
+Do I need a softener or a filter in Illinois?
Different problems, different tools. A whole-house carbon filter handles chlorine, chloramine and taste. A softener handles scale from hard water. Many Illinois homes benefit from both, and a kitchen-tap RO if lead, PFAS or nitrate appear on your CCR.
Sources: EWG; city data