New York Times

A GASOLINE additive intended to reduce air pollution, in large-scale use on Long Island for less than 10 years, is rapidly moving though the region's groundwater, penetrating drinking water supplies.

The additive, M.T.B.E., for methyl tertiary butane ether, has been found in the highest concentrations in shallow wells near gas stations and industrial areas where petroleum spilled. It is also being detected in nearly one in five of the deeper public wells that are the Island's principal sources of drinking water.

Drew and Beth Bergmann have been living a homeowner's nightmare for nearly four years.

It started in the fall of 1996, when they noticed the unmistakable smell of fuel oil permeating their tidy Massapequa home and soon discovered that oil from a neighbor's underground storage tank had seeped onto their property. After seemingly endless haggling with insurance companies, environmental companies and state officials, the contaminated soil on their property was finally cleaned up last summer.