WESTHAMPTON, N.Y. (CBSNewYork)– A dangerous chemical could be polluting the water in Westhampton Beach.

It’s called PFOS and high levels were found in the ground water in Westhampton Beach near Gabrieski Airport, WCBS 880’s Sophia Hall reported. The substance could affect a person’s immune system and blood.

Health officials in Suffolk County are now offering free testing of private wells. In the meantime, they are going door-to-door giving out bottled water to those who rely on private wells for drinking and cooking.

The Health Department also found installed groundwater monitoring wells, three of the four tested positive for PFOS. There is no concern for anyone who uses public water.