A supplemental spending bill Gov. Charlie Baker filed on Friday includes millions of dollars in new money to help cities and towns test for and treat certain chemical contaminants in their drinking water.

The family of chemicals known as per- and polyfluoroalkyl substances, or PFAS, have been detected at levels above Department of Environmental Protection guidelines in public water supplies in Ayer, Barnstable, Harvard, Hudson, Mashpee, Middleton, Shirley and Westfield, according to the DEP. Some research has suggested some chemicals in the family may be carcinogenic.

While it is not clear how much PFAS contamination in the water supply may change a home’s value, in extreme cases in other states some homeowners have had to resort to bottled water due to health concerns. According to data from The Warren Group, publisher of Banker & Tradesman, median home sale prices in half the Massachusetts communities with PFAS contamination have grown faster than the statewide median from 2016 to 2018.

DEP officials said all those communities have taken action to target PFAS, and the department is undergoing a sampling program looking for contamination in areas where PFAS has been found or is known to have been used.

The budget Baker is filing to close the books on fiscal 2019 will propose $8.4 million to test drinking water for PFAS contamination, and another $20 million to support PFAS remediation projects, according to the DEP.

PFAS chemicals have been used since the 1950s on non-stick, water-resistant and stain-resistant products. They can also be found in types of firefighting foam used by military and civilian firefighters and at airports.

Stephanie Cooper, MassDEP’s deputy commissioner for policy and planning, said the places where PFAS drinking water contamination is found are often near military installations. The department has been “really actively and proactively working on” combating PFAS contamination over the past few years, she told the News Service.

Of the new funding, Cooper said, “We hope it will even increase our proactive response to this emerging contaminant in the commonwealth and continue to protect public drinking water.”

The $8.4 million for communities to conduct PFAS testing will be in the form of a grant program administered by MassDEP, Cooper said. The money will be available for testing both public and private drinking water systems, including wells.

The $20 million for low- or no-interest loans for PFAS projects is part of $55 million the Baker administration is proposing for the Clean Water Trust, along with $35 million to fund water infrastructure projects.

Others in state government are also taking steps to address PFAS contamination.

A bill establishing an “interagency PFAS task force” (H.3851) earned the endorsement of the Environment, Natural Resources and Agriculture Committee on Aug. 26 and is now before the House Ways and Means Committee. Labeling PFAS contamination an “emerging crisis,” the bill carries a preamble specifying that, if it passes, it will take effect as soon as it is signed into law.

Also this summer, Attorney General Maura Healey joined a coalition of 22 attorneys general in urging Congress to pass legislation to help states address threats posed by PFAS.

“These toxic chemicals are putting the health of our firefighters, our military personnel, and our families in Massachusetts and across the country at serious risk,” Healey said in a July 30 statement. “We need Congress to act immediately to protect public health and help our cities and towns ensure our residents are protected from PFAS exposure and have safe drinking water.”