Wells Contaminated by MTBE Gas Additive

Advisory Report - April 2000

Wells Contaminated by MTBE Gas Additive
As many as one-third of the United States' drinking water wells may be contaminated with the gasoline additive methyl tertiary butyl ether (MTBE).

According to the Associated Press (March 22, 2000), a study by the U.S. Geological Survey and the Oregon Graduate Institute's Department of Environmental Study produced the contamination estimates by comparing the locations of leaking underground storage tanks (USTs) with those of community water supply wells.  Of the 26,000 wells studied in 31 states, about 9,000 were within one kilometer of a leaking UST.

For the past 20 years, MTBE has been used in gasoline to limit air pollution.  The U.S. Environmental Protection Agency has not established MTBE regulations but has set a drinking-water advisory of 20 to 40 micrograms per liter.  

The federal government is proposing to ban MTBE from gasoline.  MTBE, which has been found to cause cancer in laboratory animals, threatens the nation's water supply.  Even in tiny concentrations, MTBE produces a foul taste and smell in water.

For more information, visit www.epa.gov/swerust1/mtbe/index.htm.