Eight more wells that supply public drinking water have been shut down in Bucks and Montgomery Counties, and dozens of private wells have been called into question, after the Environmental Protection Agency issued more stringent guidelines on water contamination last week.

In total, 16 public wells have been closed in the two counties since the discovery two years ago that drinking water in Horsham, Warminster, and Warrington Townships had been tainted by firefighting foams. The chemicals were used over decades in the mid- to late 20th century at now-shuttered naval air bases in the area.

The new federal rules lower the amount of contaminant considered safe in drinking water. With the change, the number of private wells affected also has doubled, from 40 to 80.

In Horsham, township officials have closed an additional three public wells, for a total of five. They and the Horsham Water and Sewer Authority "will continue to be vigilant in its unified response to this matter," the agency said Monday.

The Warminster Municipal Authority also shut down three public wells on Friday "as a precaution," said general manager Timothy Hagey. All of the wells tested below the new EPA standard, but either came close to it or had previously tested above it, he said. About 20 private wells are affected, he said. Three public wells were previously taken off-line due to contamination.

In Warrington, three wells had been closed initially, and two more were shut down last week, said water and sewer director Christian R. Jones. Residents with affected private wells will be contacted by the Navy or the EPA, he said.

Perfluorinated compounds, which were commonly used in firefighting foams at the former naval air stations in Willow Grove and Warminster, have been linked to cancer and reproductive issues.

The Navy, which is working with the township and covering costs resulting from the contamination, will host two public open houses this week, at the Horsham Township Community Center from 5 to 7 p.m. Tuesday and 11 a.m. to 1 p.m. Wednesday.