Is Illinois Tap Water Safe to Drink?
Water quality data for 31 cities across Illinois. Find your city below.
Water quality in Illinois varies significantly from city to city. Across 31 cities we track, hardness ranges from 140 PPM in Oak Park South to 380 PPM in Yorkville, with a statewide average of 253 PPM. 31 of 31 cities have hard water above 120 PPM where a water softener provides measurable benefits.
1 Illinois cities have forever chemicals (PFAS) above the EPA's 2024 limit of 4 parts per trillion: Peoria (28.9 ppt). A reverse osmosis system or NSF P473-certified filter can reduce PFAS to safe levels.
Complete Illinois Guide
Statewide water quality overview, costs, and treatment recommendations.
Well Water in Illinois
Testing, treatment, and common issues for private wells.
Hardest Water Rankings
Illinois cities ranked by water hardness level.
City Treatment Guides
Sized recommendations based on each city's specific water data.
City Comparisons
Yorkville vs Oak Park South
Side-by-side water quality comparison.
Yorkville vs Washington
Side-by-side water quality comparison.
Washington vs Bolingbrook
Side-by-side water quality comparison.
Illinois Cities by Water Hardness
| City | Hardness (PPM) | Level | PFAS (ppt) | Source |
|---|---|---|---|---|
| Yorkville | 380 | Extremely Hard | 0 | Deep wells (limestone) |
| Washington | 380 | Extremely Hard | 0 | Deep wells |
| Bolingbrook | 350 | Extremely Hard | 0 | Lake Michigan via DuPage Water |
| Plainfield | 350 | Extremely Hard | 0 | Deep wells + DuPage Water |
| DeKalb South | 340 | Extremely Hard | 0 | Deep wells |
| Orland Park | 320 | Extremely Hard | 0 | Lake Michigan blend |
| Wheaton | 310 | Extremely Hard | 0 | Lake Michigan via DuPage |
| Libertyville | 310 | Extremely Hard | 5.1 | Lake Michigan via Lake County |
| Naperville South | 310 | Extremely Hard | 0 | Lake Michigan via DuPage |
| Palatine | 300 | Extremely Hard | 0 | Lake Michigan via NW Water |
| Arlington Heights | 290 | Extremely Hard | 0 | Lake Michigan via NW Water |
| Bloomington | 289 | Extremely Hard | 5.2 | Evergreen Lake, Lake Bloomington |
| Champaign | 285 | Extremely Hard | 0 | Mahomet Aquifer |
| Normal | 285 | Extremely Hard | 0 | Local wells in Mahomet Aquifer |
| Urbana | 280 | Extremely Hard | 0 | Mahomet Aquifer wells |
| Joliet | 279 | Extremely Hard | 0 | Des Plaines River wells, Lake Michigan p… |
| DeKalb | 270 | Extremely Hard | 0 | Deep bedrock wells |
| Peoria | 231 | Very Hard | 28.9 | Illinois River |
| Springfield | 227 | Very Hard | 6 | Lake Springfield |
| Belleville | 225 | Very Hard | 0 | Mississippi River alluvial wells |
| Naperville | 220 | Very Hard | 0 | Deep groundwater wells |
| Elgin | 191 | Very Hard | 15.3 | Fox River wells, Lake Michigan blend |
| Decatur | 191 | Very Hard | 0 | Lake Decatur |
| Rockford | 185 | Very Hard | 10.75 | Groundwater wells |
| Schaumburg | 175 | Hard | 0 | Lake Michigan via NW Water Commission |
| Waukegan | 165 | Hard | 0 | Lake Michigan |
| Cicero | 150 | Hard | 0 | Lake Michigan via Chicago DWM |
| Oak Park | 145 | Hard | 0 | Lake Michigan via Chicago |
| Chicago | 140 | Hard | 0 | Lake Michigan |
| Evanston | 140 | Hard | 0 | Lake Michigan |
| Oak Park South | 140 | Hard | 0 | Lake Michigan |