2026 WATER QUALITY INTELLIGENCE
Illinois Water Quality
Water quality across 193 cities in Illinois, drawn from EPA drinking-water records. Each city page shows the measured contaminants and a reproducible Purity Score.
Illinois on the water intelligence map
Open the national map to locate published city reports and inspect the underlying place records. Map coverage is not a statewide safety assessment.
How to read this report
PurityMap tracks 193 cities and 193 public water systems in Illinois. Scores reflect only what has been measured; a contaminant that was never tested is shown as pending, never as a pass.
What is being reported in Illinois?
Major water sources
Water-source summary not published
Source-water information varies by supplier and reporting period. Use a water-system record for the source description tied to a local utility.
Browse water systemsExplore Illinois city reports
These reports are presented as a directory, not a ranking. Open a city to see its supplier, measurements, interpretation and source documents.
Largest systems in Illinois
System directory not published for this state
The state report does not yet include an authored population-ordered system list. Use the national directory to search available records.
Browse water systemsWhere the record is thin
Coverage-gap detail not published
This page does not quantify missing or stale records beyond the published indicators above. Treat an absent value as unknown, not as zero.
Read the data methodologyUnderstanding the limits
What this state view does not tell you
A statewide rollup cannot tell you what is delivered to a specific address. Water quality varies by supplier, sampling period and household plumbing. Use a city or water-system report for the evidence behind a local result.
Find the system behind your tapWhat you can do next
Start with your supplier
State patterns cannot identify what reaches a specific address. Resolve your public water system before choosing treatment.
Find the system behind your tapMatch treatment to evidence
A technology is useful only when its certified claim addresses the contaminant and concentration in the local record.
Compare treatment technologiesFilters for what’s on record in Illinois
Matched to contaminant categories in this published record. Confirm the specific NSF/ANSI listing before you buy; recommendations follow the findings, and as an Amazon Associate PurityMap earns from qualifying purchases.
Best for renters/apartments facing PFAS, lead, arsenic, or nitrate who cannot modify plumbing.
Read the analysis →Best for a cheap, no-tools way to reduce lead and chlorine at a single faucet.
Read the analysis →Best for renters or off-grid use who want no-plumbing lead and chlorine reduction on the counter.
Read the analysis →Best when lead is the main concern and you want a low-cost, no-plumbing option.
Read the analysis →Frequently asked questions
How much of Illinois does PurityMap cover?
PurityMap has published records for 193 cities across 193 public water systems in Illinois. Each links back to its dated source record.
What are the most common water concerns in Illinois?
Across published Illinois city records, the contaminants that appear most are PFOA (forever chemical) (193 cities), PFOS (forever chemical) (193 cities), PFHxS (forever chemical) (193 cities), Lead (193 cities). This reflects what has been monitored and reported, not a ranking of risk.
Sources and methodology
PurityMap assembles this page from the published city and water-system records represented above. Every local report carries its own measurement dates and source documents.
About state sources
How PurityMap analyzes water data