Tap Water Results

Illinois PFAS results from EPA's final data

Report published Nov 14, 2026 · EPA UCMR 5 final data file of Oct 15, 2026 (samples collected 2023–2025) · Method · National results →

13 Illinois water systems serving 353,817 people had PFAS above a 2024 federal limit in EPA's final round of nationwide PFAS testing: 3% of the 479 Illinois systems tested, compared with 11% nationally.

479
systems tested (serving 11.1 million people)
127
had at least one PFAS detected
13
had an average above a federal limit
353,817
people served by those systems

Highest PFOA or PFOS averages in Illinois

  1. Crest Hill Water System Crest Hill · PFOA
    12.4 ppt
  2. East Alton Water System East Alton · PFOA
    12.3 ppt
  3. Galesburg Water System Galesburg · PFOA
    11 ppt
  4. Freeport Water System Freeport · PFOS
    10.8 ppt
  5. Abingdon Water System Abingdon · PFOA
    9.25 ppt
  6. Collinsville Water System Collinsville · PFOA
    9 ppt
  7. North Park Public Water District Machesney Park · PFOA
    5.75 ppt
  8. Channahon Water System Channahon · PFOS
    5.65 ppt
  9. Illinois American Water – Lincoln Lincoln · PFOA
    5.5 ppt
  10. South Elgin Water System South Elgin · PFOA
    5.4 ppt
  11. Dupo Water System Dupo · PFOS
    5.05 ppt
  12. Illinois American Water – Whispering Hills McHenry · PFOA
    4.15 ppt
  13. Illinois American Water – Peoria Peoria · PFOS
    4.1 ppt
  14. Elburn Water System Elburn · PFOA
    3.75 ppt
  15. Fox Lake Water System Fox Lake · PFOS
    2.5 ppt
The 15 Illinois systems with the highest PFOA or PFOS entry-point average (whichever is higher) in EPA's 2023–2025 testing, in parts per trillion.
Chart data as a table
Systemppt
Crest Hill Water System · Crest Hill · PFOA12.4
East Alton Water System · East Alton · PFOA12.3
Galesburg Water System · Galesburg · PFOA11
Freeport Water System · Freeport · PFOS10.8
Abingdon Water System · Abingdon · PFOA9.25
Collinsville Water System · Collinsville · PFOA9
North Park Public Water District · Machesney Park · PFOA5.75
Channahon Water System · Channahon · PFOS5.65
Illinois American Water – Lincoln · Lincoln · PFOA5.5
South Elgin Water System · South Elgin · PFOA5.4
Dupo Water System · Dupo · PFOS5.05
Illinois American Water – Whispering Hills · McHenry · PFOA4.15
Illinois American Water – Peoria · Peoria · PFOS4.1
Elburn Water System · Elburn · PFOA3.75
Fox Lake Water System · Fox Lake · PFOS2.5

Largest systems above a limit

#SystemPeople servedAbove the limit forPFOA avgPFOS avg
1Illinois American Water – Peoria
Peoria
Above: PFOS
137,575PFOS–4.1 ppt
2North Park Public Water District
Machesney Park
Above: PFOA, PFOS, PFHxS, Hazard Index
35,580PFOA, PFOS, PFHxS, Hazard Index5.75 ppt5.7 ppt
3Galesburg Water System
Galesburg
Above: PFOA
31,620PFOA11 ppt2.1 ppt
4Collinsville Water System
Collinsville
Above: PFOA, PFOS
30,616PFOA, PFOS9 ppt4.45 ppt
5Freeport Water System
Freeport
Above: PFOS
23,930PFOS–10.8 ppt
6South Elgin Water System
South Elgin
Above: PFOA
23,648PFOA5.4 ppt–
7Crest Hill Water System
Crest Hill
Above: PFOA
20,223PFOA12.4 ppt–
8Illinois American Water – Lincoln
Lincoln
Above: PFOA
15,200PFOA5.5 ppt–
9Channahon Water System
Channahon
Above: PFOS
13,380PFOS2.3 ppt5.65 ppt
10Illinois American Water – Whispering Hills
McHenry
Above: PFOA
8,300PFOA4.15 ppt–

All 13 Illinois systems above a limit

Every Illinois community water system whose UCMR 5 results averaged above a 2024 federal PFAS limit, largest first. Systems that were not tested are not listed: not tested is not the same as not detected.

Full list: 13 systems, largest first
SystemPeople servedAbove the limit for
Illinois American Water – Peoria
Peoria
Above: PFOS
137,575PFOS
North Park Public Water District
Machesney Park
Above: PFOA, PFOS, PFHxS, Hazard Index
35,580PFOA, PFOS, PFHxS, Hazard Index
Galesburg Water System
Galesburg
Above: PFOA
31,620PFOA
Collinsville Water System
Collinsville
Above: PFOA, PFOS
30,616PFOA, PFOS
Freeport Water System
Freeport
Above: PFOS
23,930PFOS
South Elgin Water System
South Elgin
Above: PFOA
23,648PFOA
Crest Hill Water System
Crest Hill
Above: PFOA
20,223PFOA
Illinois American Water – Lincoln
Lincoln
Above: PFOA
15,200PFOA
Channahon Water System
Channahon
Above: PFOS
13,380PFOS
Illinois American Water – Whispering Hills
McHenry
Above: PFOA
8,300PFOA
East Alton Water System
East Alton
Above: PFOA, PFOS
5,786PFOA, PFOS
Dupo Water System
Dupo
Above: PFOS
4,684PFOS
Abingdon Water System
Abingdon
Above: PFOA
3,275PFOA

The same list, with PFOA and PFOS averages, is in the data download.

Which limits were exceeded

PFASFederal limitSystems above itPeople served
PFOA
174,248 people
4 ppt9174,248
PFOS
251,551 people
4 ppt7251,551
PFHxS
35,580 people
10 ppt135,580
PFNA10 ppt00
GenX (HFPO-DA)10 ppt00
Hazard Index
35,580 people
1135,580

"–" in the table above means not detected. A system can be above more than one limit. EPA proposed in May 2026 to rescind the PFHxS, PFNA, GenX and Hazard Index limits. That proposal is not final.

Illinois has its own PFAS rules. 35 Ill. Adm. Code 611 identical-in-substance rule plus Hazard Index MCL. Public Act 104-0510 (June 2026) keeps them if EPA rescinds federal limits. Details. This report compares results with the federal limits only.

Data and how to cite it

Suggested citation:

Tap Water Results, "Illinois PFAS results from EPA's final UCMR 5 data" (published Nov 14, 2026, EPA data file of Oct 15, 2026). https://tapwaterresults.com/pfas/illinois/

You're welcome to quote and republish these figures with a link back. Questions from reporters: see contact.

Method

For each system we average each entry point's UCMR 5 results (non-detects count as zero, complete sets of samples only) and compare the highest entry-point average with the 2024 federal limit, using EPA's rounding. This is how EPA compares UCMR 5 results to the limits in its own data summary, and our national counts match EPA's published table within 2% (how we check). Results are monitoring data from 2023–2025, not compliance determinations, and treatment installed since then is not reflected. Full method.

Questions

How many Illinois water systems have PFAS above the limit?

13 of the 479 Illinois community water systems EPA tested in 2023–2025 (3%) had at least one entry-point average above a 2024 federal PFAS limit. They serve 353,817 people. Nationally the share is 11%.

Are these systems violating the law?

Not yet. Systems have until 2029 to meet the 2024 limits, and EPA has proposed moving the PFOA and PFOS deadline to 2031 and rescinding the other limits. EPA's UCMR 5 results are monitoring data and do not determine compliance.

Which systems were tested?

EPA's UCMR 5 tested every community water system serving more than 3,300 people and a representative sample of smaller ones. Systems that were not tested have no federal result, which is not the same as having no PFAS.

All Illinois water systems → · National results → · PFAS results for every state →

Source: U.S. EPA drinking water records and PFAS testing (UCMR 5). How we read the data.