Also known as: Methyl t-butyl ether, MTBE, Tert-butyl methyl ether, 2-methoxy-2-methylpropane
Chemical reference number (CAS): 1634-04-4

MTBE is a gasoline additive with a very strong odor. When chemicals like MTBE are added to gasoline, engines produce less carbon monoxide and other carbon-containing air pollutants by burning this “reformulated” gasoline. In cities where air quality is a problem, reformulated gasoline may contain up to 15% MTBE.

MTBE dissolves easily in water and also evaporates quickly. If it’s spilled, MTBE will evaporate quickly. However, if MTBE is spilled on soil, some of it can seep into groundwater where it can remain unchanged for many years.

When underground storage tanks leak, MTBE may be one of the first chemicals to show up in area drinking water wells. Most people can smell MTBE in contaminated water at levels as low as 100 parts per billion (ppb).