Drinking Water Contaminants - MTBE

What is MTBE?

MTBE (methyl-t-butyl ether) is a member of a group of chemicals commonly known as fuel oxygenates. Oxygenates are added to fuel to increase their oxygen content. MTBE is used in gasoline throughout the United States to reduce carbon monoxide and ozone levels caused by auto emissions. MTBE replaces the use of lead as an octane enhancer since 1979.

How does MTBE contaminate water supplies?

Releases of MTBE to ground and surface water can occur through leaking underground storage tanks and pipelines, spills, emissions from marine engines into lakes and reservoirs, and to some extent from air deposition.

How do I know if I have MTBE in my water?

You can determine if your water contains MTBE in the following ways. If your drinking water is supplied by a public water system, you can contact the system directly and ask whether they monitor for MTBE and what levels, if any, have been detected. In 2001, public water systems serving most of the population will be required to monitor for MTBE. If you have a private well, your local health department may be able to tell you if MTBE has been found in water in your area.

How can I remove MTBE from my water?

Public water systems can use existing technologies such as air stripping, granular activated carbon (GAC), reverse osmosis with activated carbon block as pre-filtrations, and advanced oxidation to remove MTBE contamination. Some home treatment units can also remove MTBE in tap water.

What is the Office of Water doing to address MTBE concerns?

Due to its widespread use, reports of MTBE detections in the nation's ground and surface water supplies are increasing. The Office of Water is actively involved in identifying the issues and addressing the concerns over the potential presence of MTBE in our water supplies. The Office of Water is participating in MTBE projects in the following areas:

EPA has established a panel of leading experts in the fields of public health, the scientific community, automotive fuels, water utilities, and local and state environmental officials to focus on the issues posed by the continued use of MTBE and other oxygenates in gasoline. The panel will look at the role of oxygenates in meeting clean air standards; evaluate its efficiency and other alternatives; assess the behavior of oxygenates in the environment; review known health effects; look at the cost of production and use and the product's availability; study causes of ground and drinking water contamination from motor vehicle fuels; and examine cleanup technologies for water and soil. In September 1999, the panel released its final report on the findings and recommendations on how best to ensure the public health and environmental protection while maintaining clean air and water benefits.

In response to the recommendations of the Blue Ribbon Panel, the Office of Water issued a memo to the States regarding concerns about MTBE and how to protect sources of drinking water. The memo encourages early MTBE monitoring under the Unregulated Contaminant Monitoring Rule and assessing the impact of MTBE sources into source water assessments, and highlights the development of a secondary drinking water standard.

MTBE and the Drinking Water Act

As part of implementing the Safe Drinking Water Act Amendments of 1996, the Office of Water has placed MTBE on the drinking water Contaminant Candidate List (CCL) for further evaluation to determine whether or not regulation with a National Primary Drinking Water Regulation (NPDWR) is necessary. The CCL divided the contaminants among those which are priorities for additional research, those which need additional occurrence data, and those which are priorities for consideration for rulemaking. The Agency determined that MTBE needs more health effects research and occurrence data before a regulatory determination can be made. Information gathered from the Agency's research and data collection efforts will assist our regulatory determination.

As part of the Drinking Water and Health pages, this fact sheet is part of a larger U.S. EPA publication:
EPA National Primary Drinking Water Regulations

Reading next