Illinois system directory
Find a community water system
Search every Illinois community water system with a current nitrate result. Open a system to see its latest reading, reporting date, nitrate band and population served.
1,782
systems with a current result
12,060,936
people served by them
719
systems carrying a supplier result
57
systems at or above 5 mg/L
3
systems listed with older records
How to read the directory: each system is placed in a band by its most recent reported result in the rolling three-year window. Purchased-water systems carry their supplier's result and are tagged. Bands describe how strongly human activity, read from nitrate, has marked a water source; they are not a safety verdict. Also listed: 3 systems whose latest report predates the window, marked “no current result” - the dated record is on the system's own page, and it is counted in no figure here.