Illinois EPA Notifies 47 Community Water Systems of Right-to-Know Requirements Triggered by Recent Rulemaking

SPRINGFIELD – The Illinois Environmental Protection Agency (Illinois EPA) is notifying the owners and operators of 21 Community Water Systems (CWSs) that there has been a detection of one or more Per- and Polyfluoroalkyl Substances (PFAS) in the most recent water sampling of those specified CWSs at levels exceeding newly enacted groundwater quality standards. The Illinois EPA is also notifying owners and operators of 26 connected CWSs that obtain water from CWSs that had one or more PFAS exceedances. Existing state Right-to-Know laws require a CWS to notify all end users when groundwater contamination poses a threat of exposure to the public above the Class I groundwater quality standards. This law establishes methods of notification and strict time frames for providing notice.

PFAS are a group of several thousand human-made chemicals that are manufactured for their oil and water-resistant properties. Since the 1940s, PFAS have been used in a wide range of consumer products, industrial processes, and in some fire-fighting foams (called aqueous film-forming foam or AFFF). This has resulted in PFAS being released into the air, water, and soil. PFAS do not easily break down under natural conditions and are often referred to as “forever chemicals.” Attached is a copy of the Public Health Notice being provided to the CWSs, which includes information on potential health effects, home water filter treatment options, and ways to minimize PFAS exposure from other sources.

On December 7, 2021, the Illinois EPA filed amendments of the Illinois Pollution Control Board’s (Board) Part 620 groundwater quality regulations to preserve and protect Illinois groundwater and to ensure that the state’s groundwater quality standards match current scientific data and methodologies. The Illinois EPA’s proposal included new groundwater quality standards for six PFAS, based on the most recent scientific information available: 

• perfluorooctanoic acid (PFOA)
• perfluorooctanesulfonic acid (PFOS)
• hexafluoropropylene oxide dimer acid, also known as GenX (HFPO-DA)
• perfluorohexanesulfonic acid (PFHxS)
• pefluorononanoic acid (PFNA)
• perfluorobutanesulfonic acid (PFBS)

On April 11, 2025, the Board’s adopted amendments to Part 620 were published in the Illinois Register, triggering this Right-to-Know notification. Attached is a complete list of the affected systems, the most recent detected concentration, and the new groundwater quality standards.

Due to the prevalence of PFAS in the environment, Illinois has been among the most proactive states in the country in developing and implementing PFAS health standards and groundwater quality standards, in order to protect its residents. Between 2021 and 2024, Illinois EPA issued seven PFAS Health Advisories to provide guidance to local officials and CWS operators in protecting the health of water consumers, and calculated 16 health-based guidance levels (HBGLs) which represent the concentrations in drinking water at which no adverse health effects are expected to occur. The adoption of Part 620 groundwater quality standards will replace five of the Health Advisories with the other two, Perfluorohexanoic Acid (PFHxA) and Perfluorobutanoic Acid (PFBA), remaining in effect until an enforceable groundwater standard exists. Additionally, U.S. EPA recently set Maximum Contaminant Levels (MCLs), which are federal drinking water standards, for certain PFAS.  CWSs will need to sample for and comply with the federal MCLs for PFAS by April 2029.

Although these state PFAS groundwater quality standards are newly established, Illinois EPA has collected PFAS data from every CWS in the state. In 2021, Illinois EPA completed a statewide investigation into the prevalence and occurrence of PFAS in finished, or treated, drinking water sampling all community water systems across Illinois. The data are available on the Illinois EPA PFAS Investigation Interactive Dashboard. Further, from 2023-2025, U.S. EPA is conducting PFAS testing in the State of Illinois under the fifth Unregulated Contaminant Monitoring Rule (UCMR 5) which is available at https://www.epa.gov/dwucmr/fifth-unregulated-contaminant-monitoring-rule-data-finder#data-finder.

Within the 47 CWSs included in this notification, only three of the six PFAS for which a groundwater quality standard now exists were detected above the groundwater quality standards. Those PFAS are PFOA (4 parts per trillion (ppt)), PFOS (4 ppt), and PFHxS (10 ppt), none of which are volatile contaminants. The 21 affected primary CWSs supply drinking water to an estimated 406,363 individuals. Those CWSs also provide potable water to 26 satellite systems, supplying drinking water to approximately 32,226 additional individuals.

The Illinois Environmental Protection Act requires the owners or operators of these CWSs to notify their customers of this contamination by mail, email, post card, text message, or telephone within five business days of official receipt of the Illinois EPA’s notice. Within seven days of sending the notices, the owners or operators of the CWS must provide the Illinois EPA with written proof that the notices have been sent.

While this notification includes only a small percentage of Illinois CWSs, other communities and residents may be at risk from PFAS exposure. PFAS are stable, persistent chemicals and will bioaccumulate in blood and organs over time. Current scientific literature indicates that people are primarily exposed to PFAS through the ingestion of food and water, including:

• ingestion of contaminated food and water, including food packaged in containers or wrappers containing PFAS.
• hand-to-mouth contact with products treated with PFAS (such as carpets and textiles) or products that contain PFAS (such as paints, and cosmetics).
• incidental ingestion of household dust.

Until additional regulations related to PFAS are promulgated at the federal and/or state level, Illinois EPA encourages all CWSs, private well owners, and residents to be proactive in addressing potential PFAS contamination, not only in drinking water, but through the other common routes of exposure. Ways to reduce exposure include:

• Choose stainless steel, cast iron, or non-stick cookware that does not contain PFAS.
• Avoid water repellents on clothing.
• Use personal care products without “PTFE” or “Fluoro” ingredients.
• Use water filters designed to remove PFAS (NSF/ANSI 53 or 58 standards).

This press release and notices provided to CWS will be posted on the Illinois EPA website at: https://epa.illinois.gov/topics/drinking-water/public-water-users/notices.html. More information regarding PFAS, including health effects and additional ways to reduce exposure, is available on the Illinois EPA PFAS webpage at https://epa.illinois.gov/topics/water-quality/pfas.html.

Additional information can be found on the Agency for Toxic Substances and Disease Registry website at: https://www.atsdr.cdc.gov/pfas/. The Illinois Department of Public Health (IDPH) provides additional information on PFAS in drinking water at: https://dph.illinois.gov/topics-services/environmental-health-protection/private-water/fact-sheets/pfas-drinking-water.html. 

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Attachments:

• PDF of News Release
• Community Water Systems Receiving Right-to-Know Notification
• Public Health Notice (English and Spanish)