PFAS in Illinois drinking water

121 drinking-water utilities in Illinois reported PFAS detections at or above the EPA minimum reporting level under UCMR 5 (the federal monitoring round that ran 2023–2025). Of those, 26 exceeded the final EPA Maximum Contaminant Level for PFOA or PFOS (4 parts per trillion), serving roughly 552,219 people.

By the numbers

• 121 Illinois water utilities with at least one PFAS compound detected
• 2,645,205 people served by those utilities
• 26 utilities above the final 4 ppt MCL for PFOA or PFOS
• 19 federal and Department of Defense sites with reported PFAS in groundwater

The interactive map below plots every reporting Illinois utility, colour-coded by whether their worst reading exceeds the federal MCL, sits below it but at or above the reporting threshold, or falls below the reporting threshold. Use the search box to find a specific utility, ZIP code or address.

Top Illinois water utilities by PFAS impact

The 15 Illinois public water systems with the most significant PFAS detections under UCMR 5, ranked by how far each system’s worst MCL-exceeding compound runs over the federal limit:

Use the interactive map above to find every utility (not just the top 15) and to search by ZIP code or address.

The biggest Illinois systems above the PFOA/PFOS MCL

Ranked by population served, the largest Illinois water utilities reporting at least one PFAS reading above EPA’s final MCL:

PFAS compounds detected in Illinois

UCMR 5 required utilities to test for 29 different PFAS compounds. The table below shows how many Illinois utilities had at least one above-reporting-level result for each compound, sorted by frequency:

Where Illinois’s PFAS contamination is coming from

EPA’s PFAS Analytic Tools also catalogue the suspected industrial, federal and accidental sources of PFAS in each state. Illinois has 19 federal facilities (mostly U.S. military installations and federal airports) reporting PFAS in groundwater, 7 EPA Superfund sites flagged for PFAS, and 16 recorded PFAS-related spills (13 of which reached surface water).

Federal and DoD sites with the highest PFAS in groundwater

The U.S. Department of Defense has reported PFAS contamination at hundreds of installations nationwide, largely tied to decades of fire-training exercises with PFAS-based firefighting foams (AFFF). These readings are taken from monitoring wells at the source site, not from drinking-water taps, but plumes from these sites are a known route into nearby public and private water supplies. Readings are in parts per trillion (ppt) of PFOS and PFOA respectively:

Superfund sites flagged for PFAS in Illinois

EPA’s Superfund program has identified the following Illinois sites with confirmed PFAS detections:

• Adams County Quincy Landfills 2&3, Quincy, Adams County. NPL status: Final. EPA site report
• Beloit Corp., Rockton, Winnebago County. NPL status: Final. EPA site report
• Estech General Chemical Company, Calumet City, Cook County. NPL status: Final. EPA site report
• Joliet Army Ammunition Plant (Load-Assembly-Packing Area), Joliet, Will County. NPL status: Final. EPA site report
• Ottawa Township Flat Glass Site, Naplate, La Salle County. NPL status: Not on NPL. EPA site report

Recent PFAS-related spills in Illinois

• 2026: Firefighting foam released in West Frankfort (Franklin County). Reached water.
• 2024: 500 gallons of aqueous film-forming foam (AFFF) released in Romeoville (Will County) by Citgo Petroleum.
• 2024: Pfas (per- and polyfluoroalkyl substances) released in Batavia (Kane County). Reached water.
• 2024: Pfas released in Datavia (Kane County) by Unknown Fire Department. Reached water.
• 2024: Aqueous film-forming foam (AFFF) released in Datavia (Kane County) by Unknown Fire Department. Reached water.

What “exceeds the MCL” means here

In April 2024 the EPA finalised the first-ever federal Maximum Contaminant Levels (MCLs) for six PFAS compounds in drinking water. The two most consequential are PFOA and PFOS, both set at 4.0 nanograms per litre (ng/L) — equivalent to 4 parts per trillion. Every red marker on the map above represents a Illinois water system whose most-recent UCMR 5 result for PFOA or PFOS sat above 4 ng/L.

EPA also issued individual MCLs of 10 ng/L for PFHxS, PFNA and HFPO-DA (GenX) and a Hazard-Index MCL covering mixtures. In May 2025 the agency confirmed the PFOA and PFOS limits would stay in place (with the compliance deadline extended to 2031), and announced its intent to rescind the four other limits. We continue to flag exceedances of the published April 2024 MCL for those compounds and label them as “under EPA reconsideration” so the rule status is honest and current.

Yellow markers mean PFAS were detected at or above EPA’s reporting threshold (the minimum reporting level) but no individual compound exceeded an MCL. Detection at any level is not necessarily a regulatory violation, but it is a signal that PFAS treatment may be needed before the 2031 compliance deadline.

Methodology and data sources

• Drinking-water detections: EPA PFAS Analytic Tools, UCMR 5 layer. Filtered to Illinois samples at or above the minimum reporting level. We aggregate the raw 2023–2025 sample records to one entry per public water system, taking the most-recent reading per compound.
• Superfund sites: EPA PFAS Analytic Tools, Superfund-with-PFAS layer. Includes National Priorities List sites and Superfund Alternative Approach sites where PFAS has been detected.
• Federal and DoD sites: EPA PFAS Analytic Tools, federal-sites layer. PFOA and PFOS values are maximum readings from groundwater monitoring wells at each installation, not finished drinking water.
• Spills: EPA PFAS Analytic Tools, spills layer. Covers reported releases involving PFAS-containing materials.

UCMR 5 only required community water systems serving 3,300 or more people, plus a representative sample of smaller systems, to test for PFAS. Private wells, very small public systems, and bottled water are not in this dataset. Absence of a dot on the map does not mean absence of PFAS.

What you can do

• Check whether your utility appears in the table above or on the map. If it does, your utility is required to come into compliance with the federal PFOA/PFOS MCL by 2031 — usually via granular activated carbon, ion-exchange resin or reverse osmosis treatment.
• If you are on a private well in or near a flagged area, consider independent PFAS testing through a state-certified laboratory.
• Look up your most recent Consumer Confidence Report (CCR), which utilities are required to publish annually. PFAS results from UCMR 5 must now appear there.
• If you want point-of-use protection, only filters certified to NSF/ANSI 53 or NSF/ANSI 58 for PFOA and PFOS reduction will reliably remove PFAS.

Related

• National PFAS contamination map (all 50 states)
• US Superfund sites map
• EPA PFAS Analytic Tools (raw data)
• EPA PFAS National Primary Drinking Water Regulation