In this Aug. 1, 2018 photo, a water tower stands above a residential neighborhood in Horsham, Pa. In Horsham and surrounding towns in eastern Pennsylvania, and at other sites around the United States, the foams once used routinely in firefighting training at military bases contained per-and polyfluoroalkyl substances, or PFAS. EPA testing between 2013 and 2015 found significant amounts of PFAS in public water supplies in 33 U.S. states.
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