The Maine Department of Environmental Protection has found high levels of PFAS, also known as 'forever chemicals,' in roughly a third of drinking water well samples tested in the town of Unity.

The DEP's Susanne Miller says the agency is in the process of investigating PFAS contamination at more than a thousand sites where treated municipal sludge was previously applied.

"I think it's important to take all of this data in context, which is that the data we're looking at are very targeted sites," Miller says. "We're looking at sites we anticipate we're going to find some level of contamination. We're not investigating every single well in the state."

When a private residential well exceeds the state's interim drinking water standard of more than 20 parts per trillion, Miller says the DEP will install a filtration system. She says homeowners whose wells are not included in the investigation but are concerned about PFAS can contact the DEP for guidance on how to conduct their own testing. PFAS is a group of chemicals found in numerous products that have been associated with health issues.