PFAS · Illinois

PFAS in Illinois drinking water: EPA’s final survey results

EPA’s national PFAS survey (UCMR 5) tested 479 of the community water systems that serve homes in Illinois. 127 found at least one of 29 PFAS above the laboratory reporting level, and 13 had a PFOA or PFOS sampling-location yearly average at or above EPA’s 4.0 ppt limit. Samples were collected from January 2023 to April 2026.

In focus27%of surveyed systems found PFAS

Public records. Clearer context.

Data as of EPA UCMR 5 final release, August 2026 (file dated Aug 28, 2026) · EPA SDWIS 2026Q2 (file dated Jul 9, 2026). How we build these pages

479

Illinois community systems in EPA’s survey

serving about 11,052,183 people

127

found at least one PFAS

27% of surveyed systems; about 2,651,896 people served

PFOA or PFOS yearly average at or above the MCL

compared the way EPA does: the average of a complete sampling set

105

lithium at or above EPA’s health reference level

lithium was part of the same survey

PFBA was the compound Illinois community systems found most often: 84 of 479 tested systems measured it above the reporting level. Across the country, 35% of surveyed community systems found at least one PFAS; in Illinois the share is 27%. The largest Illinois system with a detection, Aurora, serves 183,000 people and found 4 of the 29 compounds.

Which PFAS were found most often in Illinois

Each row counts the Illinois community water systems where that compound was measured above the reporting level at least once. A detection is a measurement, not a violation: most of these compounds have no federal limit.

Compound	Systems where found	Systems tested	Share
PFBA	84	479	18%
PFPeA	59	479	12%
PFHxA	42	479	9%
PFBS	40	479	8%
PFHxS	19	479	4%
PFOS	19	479	4%
PFOA	17	479	4%
PFHpA	6	479	1%
6:2 FTS	3	479	1%
4:2 FTS	1	479	0%
PFNA	1	479	0%
PFPeS	1	479	0%

Illinois systems with the most PFAS found

The 10 surveyed community water systems that found the most different PFAS, with PFOA and PFOS compared to EPA’s 4.0 ppt limits on the yearly average at the highest sampling location. Larger systems come first when counts tie.

Water system	People served	PFAS found (of 29)	PFOA	PFOS
Collinsville IL1194280	29,500	8	9.0 ppt at or above the MCL	4.5 ppt at or above the MCL
East Alton IL1190200	5,786	8	12.3 ppt at or above the MCL	11.2 ppt at or above the MCL
North Park Pwd IL2015500	35,580	7	5.8 ppt at or above the MCL	5.7 ppt at or above the MCL
Il American-Pekin IL1795040	31,731	7	— not detected above the reporting level	2.2 ppt below the MCL
Crest Hill IL1970250	21,169	7	12.4 ppt at or above the MCL	— not detected above the reporting level
Prairie Path Water Co-Whispering Hills IL1115700	8,300	7	4.2 ppt at or above the MCL	— not detected above the reporting level
Channahon IL1970200	13,380	6	2.3 ppt below the MCL	5.7 ppt at or above the MCL
Il American-Peoria IL1435030	137,575	5	— not detected above the reporting level	4.1 ppt at or above the MCL
Galesburg IL0950200	31,620	5	11.0 ppt at or above the MCL	2.1 ppt below the MCL
South Elgin IL0890800	23,648	5	5.4 ppt at or above the MCL	— not detected above the reporting level

Counties with the most systems that found PFAS

Madison County 17 of 19 surveyed systems
Cook County 8 of 109 surveyed systems
Will County 8 of 22 surveyed systems
St. Clair County 8 of 10 surveyed systems
Kane County 7 of 18 surveyed systems
McHenry County 6 of 12 surveyed systems
Williamson County 5 of 7 surveyed systems
DuPage County 4 of 32 surveyed systems

How to read these numbers

UCMR 5 asked every community and non-transient non-community water system serving 3,300 or more people, and a sample of smaller ones, to test for 29 PFAS and lithium. EPA published the final data in August 2026; its samples were collected from January 2023 to June 2026. A system that was not in the survey has no result here; that is not the same as having no PFAS.

UCMR 5 is a one-time national monitoring survey. Its results do not indicate compliance or non-compliance with the PFAS Maximum Contaminant Levels, which are enforced on running annual averages and take effect in 2029 (EPA has proposed allowing extensions to 2031). A single result above a limit on this page is a measurement, not a violation.

See how to read UCMR 5 results and our methodology for how systems are matched to places.

After Illinois’s PFAS results

Find your system. Then read its report.

State recordsAll Illinois water recordsCounties, ZIP reports, lead results and violations for the whole state.FiltersChoosing a PFAS filterHow to check a filter’s certified PFAS reduction before you buy.Your utilityFind your annual water reportYour utility’s Consumer Confidence Report will list its own PFAS results and any treatment plans.

County pages

Illinois water records

Sources

EPA UCMR 5 occurrence data, samples collected 2023-01-03 – 2026-06-17, final release, August 2026 (file dated Aug 28, 2026); EPA SDWIS via ECHO, 2026Q2 extract (file dated Jul 9, 2026); EPA service-area boundaries v3.0; Census 2020 ZCTAs. Database prepared 2026-09-03.