Pennsylvania is testing the water to find chemicals like PFAS. This is a class of chemicals that is widely used in the US since the 40s. PFAS are man-made. They are used in waterproof tanks.
The American Water Works Association, estimates the cost to address PFAS in water supplies at 3 to 38 billion dollars. Scientists discovered these chemicals have all sorts of great properties. They are nonstick, water repellant, and stain repellent.
The Environmental Protection Agency found the in the nonstick coating on pans. The fabric of your furniture could have been coated with a spray containing PFAS. Food containers sometimes have chemicals inside.
PFAS have become a high-profile contaminant, polluting areas near manufacturing facilities that make or use them and military sites like airbases. Researchers are still trying to fully understand the health effects of PFAS but have determined that some are carcinogenic and toxic to multiple systems.
The Delaware Senate has passed a bill that purports to restrict the use of firefighting foam containing certain compounds associated with cancer and other health problems while allowing continued use of the foam to fight fires. They have been linked to a wide range of health ailments including kidney and testicular cancers, changes in liver, thyroid and immune system functions, and developmental problems. They do not easily break down in the environment. They have contaminated groundwater in and around military bases and other aviation facilities around the country, including Dover Air Force Base and the New Castle County Airport.