Every Illinois public water system that reported a PFAS detection during EPA UCMR 5 monitoring, how many sit above the 2024 federal limits, and the standard Illinois applies. Concentrations are in nanograms per litre, the same unit as parts per trillion.
This is the United States view of the North American PFAS dataset. The complete dataset, including all 3,452 US systems and 97 Canadian sites, lives on the main PFAS contamination map.
State enforceable standard
The Pollution Control Board adopted these as groundwater quality standards in docket R22-18, effective 28 March 2025, with the same values for Class I and Class II groundwater. Five of the six match the federal MCLs, and PFBS is set as a flat 2,000 ng/L rather than through a Hazard Index. They are not drinking water MCLs, and public water systems in Illinois follow the federal rule.
Compound
Limit (ng/L)
Note
PFOA
4
Class I and Class II groundwater standard
PFOS
4
Class I and Class II groundwater standard
PFHxS
10
Class I and Class II groundwater standard
PFNA
10
Class I and Class II groundwater standard
PFBS
2,000
Class I and Class II groundwater standard
HFPO-DA
10
Class I and Class II groundwater standard
Illinois EPA, Part 620 standards comparison table
US EPA PFAS National Primary Drinking Water Regulation (2024)
Last reviewed 2026-08-13. Verify against the agency source before making a compliance or remediation decision.
Full Illinois regulatory brief
Ranked by how far the worst single compound sits above its 2024 federal limit. Values are the maximum each system reported during its UCMR 5 monitoring period.
Water system
PWSID
Worst compound
Max ng/L
Times the limit
Collinsville, Il
IL1194280
PFOA
18
4.5x
East Alton
IL1190200
PFOS
17
4.3x
Galesburg
IL0950200
PFOA
14
3.5x
Freeport
IL1770200
PFOS
14
3.5x
Crest Hill
IL1970250
PFOA
13.7
3.4x
New Baden
IL0274700
PFOS
9.4
2.4x
Abingdon
IL0950050
PFOA
9.4
2.4x
Prairie Path Water Co. - Whispering Hills
IL1115700
PFOA
8.3
2.1x
Il American-Valley View
IL0437350
PFOA
7.3
1.8x
North Park Pwd
IL2015500
PFOS
7.3
1.8x
Freeburg
IL1630600
PFOS
7
1.8x
Il American-Peoria
IL1435030
PFOS
6.5
1.6x
Channahon
IL1970200
PFOS
5.9
1.5x
South Elgin
IL0890800
PFOA
5.7
1.4x
Il American - Lincoln
IL1075030
PFOA
5.7
1.4x
Pleasant Valley Pwd
IL1435470
PFHxS
14
1.4x
Dupo
IL1630350
PFOS
5.6
1.4x
Dixmoor
IL0310660
PFOS
5.5
1.4x
Fox Lake
IL0970200
PFOS
5
1.3x
Mount Carmel
IL1850200
PFOS
4.8
1.2x
Open the full map and filter Illinois pins
Every count above is read straight from a published government file. Nothing is modelled, averaged, or estimated. The rules below are the exact rules used to produce the figures for Illinois.
Who is in UCMR 5. All public water systems serving more than 3,300 people, plus a national sample of 800 smaller systems. Private wells and most small systems are not monitored, so they cannot appear here.
Which systems are listed. Only systems whose state field is IL and that reported at least one measured PFAS detection. Systems that monitored and found nothing are not shown, and their absence is not evidence of contamination. That gives 123 systems in Illinois.
Systems that cannot be placed. 87 systems nationally reported a detection but have no serviced ZIP code published by EPA, so they carry no location and are excluded from these counts. National totals on the map page include them.
Which value is used. The highest result a system reported for each compound across its sampling events. Results flagged by EPA as non-detects are excluded, as are the lithium results carried in the same file.
The above a limit count. A system is counted when its maximum result for a compound exceeds the 2024 federal Maximum Contaminant Level: 4 ng/L for PFOA and PFOS, 10 ng/L for PFHxS, PFNA, and HFPO-DA. That is 27 systems in Illinois.
The Hazard Index count. Calculated with EPA's own mixture method for PFHxS, PFNA, HFPO-DA, and PFBS. A system is counted when the index is above 1. That is 6 systems in Illinois.
What monitoring data is not. Exceeding a 2024 limit in this dataset is not a compliance violation. The federal limits carry a 2029 compliance date, which EPA proposed on 18 May 2026 to move to 2031 for PFOA and PFOS in a rule that is not final, and treatment may have been installed since the sample was taken.
If any figure on this page does not match its source file, tell Nelson and it will be corrected or removed.
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