Is MTBE banned in the United States?
No. There is no nationwide federal ban on methyl tert-butyl ether (MTBE) in the U.S., but more than two dozen states prohibit or heavily restrict it in gasoline, and refiners largely phased it out after 2005–2006. Today, U.S. motor gasoline seldom contains MTBE, with ethanol serving as the dominant oxygenate.
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What MTBE is and why it was used
MTBE is a fuel oxygenate and octane booster that became widespread in the 1990s under the Clean Air Act’s reformulated gasoline program. It helped gasoline burn more completely, lowering certain tailpipe emissions, but it proved highly mobile and persistent in groundwater. Taste and odor problems at very low concentrations, coupled with contamination from leaking underground storage tanks, drove public concern and policy changes.
Federal policy: No national ban, but the mandate ended
The federal government never banned MTBE. Instead, Congress removed the oxygen-content requirement for reformulated gasoline in the Energy Policy Act of 2005 (effective in 2006) and created the Renewable Fuel Standard, which spurred the shift to ethanol. Without the federal oxygenate mandate and amid litigation and cleanup liabilities, U.S. refiners and blenders largely stopped using MTBE in on-road gasoline.
State actions: Bans and restrictions across the map
Beginning in the early 2000s, states acted on their own. More than two dozen states—covering most large gasoline markets, including California and New York—have enacted bans or strict limits on MTBE in motor fuel to protect drinking water. These state measures, combined with liability risks, effectively removed MTBE from mainstream gasoline supply even absent a federal prohibition.
What to know at a glance
The following points summarize the current regulatory and market reality for MTBE in the U.S. and why consumers rarely encounter it in gasoline today.
- No federal ban exists on MTBE; the EPA has not set a national primary drinking water standard for it.
- EPA has issued a non-enforceable drinking water advisory (commonly cited at 20–40 micrograms per liter) based on taste and odor considerations.
- More than two dozen states ban or tightly restrict MTBE in gasoline, and refiners phased it out of on-road fuel after 2005–2006.
- Ethanol is now the primary oxygenate in U.S. gasoline under the Renewable Fuel Standard.
- Legacy contamination persists at some leaking tank sites; state cleanup programs and water utilities continue remediation and monitoring.
Taken together, these factors mean MTBE is functionally absent from everyday U.S. gasoline, even though no single federal law outright prohibits it nationwide.
How the phase-out unfolded: Key milestones
This brief timeline captures the policy shifts and market responses that drove MTBE’s decline in U.S. gasoline.
- 1990s: Reformulated gasoline rules boost MTBE use to meet oxygen content and octane needs.
- Late 1990s–early 2000s: Groundwater contamination incidents prompt state-level bans and restrictions.
- 2005–2006: Energy Policy Act removes federal oxygenate requirement and launches the Renewable Fuel Standard; ethanol rapidly displaces MTBE.
- Late 2000s onward: MTBE effectively disappears from on-road gasoline; cleanup and litigation continue in affected areas.
These developments shifted both policy and market incentives, making ethanol-blended gasoline the standard and relegating MTBE to niche or non-fuel uses.
Current status: Where MTBE may still show up
Drinking water and cleanup
While many utilities have addressed contamination, MTBE remains a concern at some legacy sites. EPA’s drinking water advisory focuses on taste and odor thresholds, and several states have their own enforceable limits. Remediation continues through state and local programs, often tied to leaking underground storage tank funds.
Non-fuel and specialty uses
MTBE may appear in limited industrial applications or specialty fuels where permitted, though volumes are small compared with historical gasoline blending. State prohibitions typically target motor fuel use, and any allowable uses must comply with local environmental rules.
Bottom line
MTBE is not federally banned in the United States, but state prohibitions and market forces have effectively removed it from mainstream gasoline. Ethanol now fills the oxygenate role nationwide, and MTBE’s legacy is most visible in groundwater protection and cleanup efforts rather than in current fuel formulations.
Summary
There is no U.S. federal ban on MTBE, yet state-level bans and the end of the federal oxygenate mandate have led to a de facto national phase-out in gasoline since the mid-2000s. Ethanol dominates as the oxygenate of choice, while MTBE’s footprint today is largely tied to historical contamination and limited non-fuel uses.
What countries still use MTBE?
The demand for MTBE in countries, such as China, India, South Korea, Mexico, and Saudi Arabia, has been increasing due to increased demand for gasoline from the automotive industry, which has been leading to an increase in the gasoline production in the aforementioned countries, in order to cater to the rising demand.
Is MTBE regulated by the EPA?
In December 1997, EPA’s Office of Water released a non-regulatory advisory for MTBE in drinking water. The EPA advisory is not a mandatory standard for action and is not federally enforceable, but provides guidance for communities that may be exposed to drinking water contaminated with MTBE.
Is MTBE used in the US?
The MTBE controversy concerns methyl tert-butyl ether (MTBE), a gasoline additive that replaced tetraethyllead. MTBE is an oxygenate and raises gasoline’s octane number. Its use declined in the United States in response to environmental and health concerns.
Is MTBE still added to gasoline?
MTBE was added to gasoline in the mid-to-late 1980s to increase fuel efficiency and decrease pollution, with peak usage during the 1990s. When MTBE started to be detected in groundwater, several states banned its use in gasoline and it has not been added to gasoline in the United States since 2005.
