After years of testing, the state Department of Environmental Protection said Tuesday it finally had identified a potential culprit for the PFAS contamination that has left residents in a Bucks County neighborhood without clean tap water for three years.

The state agency pointed to Bergey’s Realty Co. and Bergey’s Retread Technologies, the company that owned the site where 150,000 tires caught fire in 1986. Firefighting foam that has since been linked to PFAS was used to contain that blaze, and seeped into the soil and waterways, the DEP said.

Affected residents in East and West Rockhill Townships had long blamed Bergey’s for the contamination, citing memories and photographs of the firefighting foam on the tires and neighboring land.

But state officials had to complete a time-consuming investigation before they would confirm a potential source — a critical step in determining who should pay for fixing it. They have been investigating, monitoring, and testing in the area, known as Ridge Run, since 2016.

Identifying who is responsible could now clear the way for cleanup, including a permanent fix for the dozen houses with contaminated drinking water.

Residents, however, remained frustrated Tuesday with the slow pace of the state’s bureaucratic process. They have had to use bottled water for drinking, cooking, and brushing their teeth for three years.

“I am extremely angry,” Angela Goodwin, whose West Rockhill property overlooks Bergey’s, wrote in an email. “I know the letter states that they could be responsible, but it has been three years. I would think by now they would be making them responsible or not.”

PFAS have been linked to cancer and other health problems. They also contaminated public drinking water systems around Horsham, Warrington, and Warminster Townships and in states across the country.

The state will “attempt to engage with” Bergey’s to determine what steps are needed to determine the extent of the contamination and clean it up, the DEP said.

“We understand these investigations can take longer than expected and that the process can be frustrating to those living with impacts,” said DEP regional director Pat Patterson. “While this is an important step, we still have much work to do.”

An attorney who has represented Bergey’s did not respond to a request for comment on Tuesday.