Per- and polyfluoroalkyl substances, or PFAS, were detected in 96% of waterways tested in Pennsylvania and 91% of waterways tested in New Jersey, according to U.S. Environmental Protection Agency data reported Oct. 14, 2026. The findings point to the broad presence of the chemicals across the region, including the Philadelphia area and South Jersey. PFAS are a large family of manufactured chemicals used in products and industrial processes. They are often called “forever chemicals” because they can persist in the environment rather than breaking down quickly. The detection rates apply to waterways that were tested; they do not mean every river, creek or stream in either state was sampled. Nor does finding PFAS in surface water alone establish that nearby tap water contains the chemicals or that people have been exposed at harmful levels. Drinking-water systems require their own testing. The data underscore the challenge facing communities and regulators as persistent contaminants move through waterways and ecosystems. Understanding local risk depends on where samples were collected, which PFAS were found, and at what concentrations—information that matters for decisions about monitoring, cleanup and protecting residents’ water supplies.