Testing has revealed that wells in Kittery contain “forever chemicals” that may have traveled through well systems and drinking water, the Maine Department of Environmental Protection found.

Last month, the department said 10 Kittery homes will have to test their wells after routine per- and polyfluoroalkyl chemical testing found the chemicals in three test wells. The department recently discovered that 1 in 4 homes contained levels of the chemicals, also referred to as PFAS, that would be harmful if ingested, The Portsmouth Herald reported.

All the homes that tested positive for the chemicals are within 1,000 feet from the town’s dumping location, Kittery Resource Recovery Facility. The contamination source is reportedly from Kittery’s landfill that closed in 1993. A town report said water from decomposed waste in landfills can contain high levels of chemicals.

The town has provided bottled drinking water for the residents that water contamination affected and will potentially install a water filtration system, Chris Redmond, an employee for the department’s landfill closure and remediation program said.

Town Manager Kendra Amaral said Kittery officials are concerned about the testing results and “we are taking every step we can to address the immediate issues as well as trying to make sure that the neighborhood is aware of what this means and that we’re looking to address it in the long term.”

PFAS are sometimes called “forever chemicals” because they last so long in the environment. These chemicals are found in products like pots and pans, carpets, clothing and personal care products.

The Maine Center for Disease Control said the chemicals could cause an increased risk of kidney and testicular cancer, high cholesterol levels and changes in liver enzyme levels.