MTBE

Methyl tertiary butyl ether (MTBE) is used as an oxygenate additive to gasoline. The use of oxygenates in gasoline is required in certain areas of the United States where air quality standards are exceeded.

The US Environmental Protection Agency initiated the Oxygenated Fuel Program in 1992 and the Reformulated Gasoline Program in 1995 in response to requirements of the 1990 Clean Air Act (CAA) Amendments. MTBE has been favored over other potential oxygenates because of its low cost, ease of production, and favorable blending characteristics with conventional gasoline.

Although improvements in air quality have been made with the use of oxygenate additives, contamination of drinking water supplies has occurred as a result of MTBE use. MTBE is especially problematic because it has a low taste and odor threshold, tends to migrate in subsurface systems much faster than other constituents of gasoline, is difficult to remove from water at low concentrations via conventional treatment processes, and because of concerns regarding potential health impacts.

There have been many federal and state regulatory, legislative and legal developments in recent years responding to the emergence of widespread MTBE contamination of water supplies. See the Related Resources links for details. 

The MTBE Resource Center has been set up by the AWWA Organic Contaminants Control Committee to help utilities grapple with the technical and regulatory issues arising from MTBE contamination.