New federal testing has turned up per- and polyfluoroalkyl substances, or PFAS, in drinking water at multiple sampling locations across the St. Louis metro area, and some readings come in several times higher than the U.S. Environmental Protection Agency’s newly adopted thresholds. The latest wave of results is rolling out as the EPA finishes uploading its UCMR 5 testing data and local utilities scramble to figure out what the numbers mean. From suburban Missouri to river towns in Illinois, residents are now sorting through which systems tested positive and how soon fixes might realistically arrive.
Where tests found PFAS
According to the EPA UCMR 5 Data Finder, the results cover monitoring conducted from 2023 through 2025 and already represent roughly 95% of the dataset the agency expects to receive. The online tool lets users pull up individual public water systems and compare sampling-location averages to the federal thresholds the EPA has set for certain PFAS compounds.
Local reporting that combined the EPA data with a USA TODAY map identified multiple systems in the FOX 2 viewing area with detections at or above those EPA thresholds. As covered by FOX 2, notable detections include Collinsville, where one sampling location showed a highest single measurement about 4.5 times the EPA limit with eight PFAS detected, and East Alton, at about 4.3 times the limit. St. James PWS clocked in at about 2.5 times the threshold with seven PFAS detected, Ocala Heights S/D in Des Peres at about 1.6 times with six PFAS, St. Peters PWS at about 1.2 times with four PFAS, and Dupo, Illinois at about 1.4 times with three PFAS. The coverage also pointed out that much smaller systems are on the list too, including the Circle C mobile-home park in Beaufort, which serves roughly 75 customers and still registered detections above the threshold.
What the numbers mean for tap water
The EPA’s UCMR monitoring program is designed to document how often these contaminants show up and at what levels; by itself it is not a formal compliance check. The agency’s PFAS drinking water rule separately establishes enforceable Maximum Contaminant Levels for specific PFAS and lays out a schedule for monitoring and compliance. According to the EPA, systems must complete initial monitoring within three years, and compliance with the MCLs is expected to begin in 2029. The EPA Fact Sheet details the MCLs, trigger levels and monitoring requirements for utilities and regulators.
Local responses and planned fixes
Utilities and local officials say that figuring out which treatment technology to use, how to engineer it into existing systems and how to pay for it is not a quick process, and they warn that installing advanced filtration or switching to new water sources can carry a steep price tag. FOX 2 reported that Collinsville officials have announced a proposed retrofit to tackle groundwater detections, but that project is not expected to be finished until 2029, a timeline that mirrors what many systems are floating as they sketch out upgrades.
How residents can check and protect themselves
Customers who want to know whether their system showed PFAS detections can start with the utility’s Consumer Confidence Report, which is required to include UCMR 5 results, or by calling the water provider directly. Community water systems must share monitoring results in those reports and issue public notifications if they violate standards. The EPA’s online tools and the UCMR 5 data downloads can also help residents track down system-level results. In the meantime, anyone with concerns can ask their water provider about short-term precautions such as bottled water or certified point-of-use filters while long-term treatment projects are planned and built. We will continue to watch for additional uploads to the EPA database and for announcements from local utilities as systems complete monitoring and lock in their PFAS response plans.
