UNITY — More than one-third of a sample of residential water wells in town recently were found to contain unsafe levels of so-called “forever chemicals” after state officials recently ramped up efforts to test for PFAS in local water supplies.

Of the 91 water wells the state tested in Unity as of late November, 33 of those had higher PFAS levels than what the state says is safe, according to data from the Maine Department of Environmental Protection.

The spate of water testing comes after a cluster of wells at residences near Depot Street were found to be unsafe, said David Madore, the department’s deputy commissioner. Though the Department of Environmental Protection first began investigating PFAS spreading near downtown Unity in June of this year, Madore said there is no timeline for when the investigation will be complete.

Madore said the department initially identified 17 homes on Depot Street with PFAS concentrations above 20 parts per trillion, which is the state’s safety standard. State officials are “in the process of procuring a contract to install drinking water filtration systems at these homes,” Madore said.