The warnings came in the mail this spring to 47 community water systems serving more than 400,000 Illinois residents: Elevated levels of harmful PFAS, better known as “forever chemicals,” had been found in their drinking water.
The notice, mailed by the Illinois Environmental Protection Agency in April, was triggered by a tighter federal PFAS standard adopted by the state’s pollution control board that month. The state told the water systems to immediately notify their customers by mail, email, post card, text message or telephone.
In some cases, other communities would tap into these water systems in an emergency, so the Illinois EPA sent another notice in May to warn those other systems.
PFAS — perfluoroalkyl and polyfluoroalkyl substances — are found in products ranging from clothing to food wrappers and have caused water problems nationwide. Researchers have linked even low levels of chronic PFAS exposure to health effects such as kidney cancer, thyroid disease and ulcerative colitis. Illinois’ revised groundwater quality criteria cover six PFAS chemicals, with notices issued if high levels of any one compound are detected.
“The possible health effects from PFAS depend on numerous factors, including how much a person is exposed, so it is important to minimize PFAS exposure,” the state EPA said in its letter. It noted that residents who wanted to take action could treat their own water with carbon filters or reverse osmosis — but it also warned that in-home treatments “may not always reduce PFAS below levels of concern.”
The community water system in Crest Hill, 30 miles southwest of Chicago, was among those receiving the Illinois EPA letters. The agency said two PFAS chemicals — perfluorooctanoic acid (PFOA) and perfluorohexanesulfonic acid (PFHxS) — were found in excessive quantities in two of the city’s wells. PFOA was detected at 13.7 parts per trillion, over three times its regulated limit of 4 ppt. Meanwhile, PFHxS was found at 12.2 ppt, exceeding its 10 ppt limit.
Crest Hill informed residents about the PFAS issue by mail in April, noting that six of the city’s eight wells were uncontaminated. City engineer Ron Wiedeman said state law mandates municipalities exceeding PFAS limits to continue water analysis until 2027, with full results sent to all customers at that time. A large-scale PFAS reduction plan must then be implemented by April 2029.
Wiedeman also acknowledges residents’ confusion regarding when officials became aware of the contamination. Despite analyzing Crest Hill’s wells in 2021 and 2023, the Illinois EPA did not inform cities of the potential dangers until this April, after the state adopted the U.S. Environmental Protection Agency’s standard set last year.
“There were no maximum restrictions on PFAS, so we didn’t know if we were above or below regulatory limits,” Wiedeman said. “When [Illinois EPA] officially adopted those regulations, then we knew we were over the limits.”
Other Chicago-area community water systems receiving letters from the Illinois EPA include Channahon, Fox Lake, South Elgin and the Criswell Court mobile home park in Joliet, according to the agency.
A lot of work ahead on PFAS
PFAS pollutes the environment through spills, leaks, industrial processes and the disposal of PFAS-containing products. The many opportunities for contamination mean that affected community water systems can’t always determine how the chemicals ended up there.
For instance, a PFAS chemical found in firefighting foams called fluorotelomer sulfonate had been used in Crest Hill, but no direct link exists between its usage and the detected contamination, Wiedeman noted.
“Unfortunately, there is nothing that we can directly point at,” Wiedeman said. “We know of some incidents in the city where fire foam was used, but the locations don’t match to where we have the highest readings of PFAS.”
He added: “PFAS is everywhere, but a lot of people don’t know it.”
As part of the new groundwater quality regulations, the Illinois EPA is collecting PFAS data from every water system in the state. The agency provided guidance to local officials through seven PFAS health advisories issued between 2021 and 2024, EPA public information officer Kim Biggs said in an email.
“We will continue our work with community water systems to ensure residents receive information on these important issues, as well as working with systems to determine any necessary actions to reduce exposure to PFAS,” Biggs said.
Crest Hill’s long-term strategy for mitigating PFAS risk involves transitioning to highly treated Lake Michigan water. Wiedeman said the pipeline infrastructure to make that possible likely will be completed in 2030, when the city’s water will be purified by Chicago’s state-of-the art treatment plants.
“That will handle PFAS or any future contaminants that get into the water,” Wiedeman said.
Processes to mitigate PFAS include reverse osmosis, which harnesses high-pressure membranes to filter out toxins. Meanwhile, researchers at the University of Illinois Chicago are investigating ways to not just remove but utterly eliminate these chemicals.
Led by chemical engineering professor Brian Chaplin, the UIC system employs reactive electrochemical membrane filtration, using adsorbents and catalysts on the membrane to trap and destroy PFAS as tainted water passes through.
The $1 million project, funded by the U.S. Department of Energy’s National Alliance for Water Innovation, is in the prototype phase. Researchers will then test the system in California’s Orange County water district.
“Our goal is to avoid the need for further treatment and destroy PFAS right on site,” Chaplin said. “When we complete this work, this new technology will be ready to be piloted in the industrial and municipal wastewater sectors.”
The system could operate on a smaller scale as well, similar to a water-pitcher filter or water softener. Illinois residents concerned about PFAS can also dump their non-stick cooking pans and similar polluting products, Chaplin added.
“Use cast iron and stainless steel instead,” he said. “Consumers have more power than they realize. If enough people don’t buy these products, the market will have to adjust.”
