Private water wells in a swath of Suffolk County are being tested amid new water quality concerns.

Potentially dangerous contaminants were first found in a water well on Church Street in Bohemia, and health officials now say that private wells will be tested throughout a large area that encompasses Oakdale, Sayville, West Sayville and Bohemia, as well as parts of Holbrook and Ronkonkoma.

It comes after the pollutant perflourooctane sulfonate, known commonly as PFOS, was found in levels that exceed EPA standards. The source of the chemical is believed to be a firefighting foam that was used at nearby MacArthur Airport -- which was recently listed as a possible Superfund site.

Health officials say water contaminated with PFOS is not dangerous for use in bathing, but it can cause health problems if consumed. Residents who use private wells in the specified area are being advised not to drink or cook with their water.

The health department says the chemical is not in the public water supply, so those residents shouldn't be concerned. But people who are serviced by the wells can pick up free bottled water while the testing is underway. The bottled water is available every day from 7:30 a.m. through 2 p.m. at the Bohemia Recreation Center on Ruzicka Way.

Islip Town officials say if residents receive a Suffolk County Water Authority bill, they are not affected.

Anyone with questions about the testing can call the Suffolk County Department of Health at 631-852-5810.