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MtBE - Methyl-tert-Butyl Ether: 
Good for the air -- Not so good for the water

Methyl Tertiary Butyl Ether (MtBE), an oxygenate added to gasoline to reduce air pollution, has become a contaminant of great concern.  The chemical itself is not new.  In fact, it has been manufactured since the late 1970’s and has been widely used since the early 1990’s.  The recent publicity is the result of various amounts of MtBE discovered in well and municipal systems throughout the country.  The AWWA reports that it has been found in areas from the rural towns of Ronan, Montana and Spring Green, Wisconsin to major metropolitan areas such as Dallas, Las Vegas and Denver.  Most detections have been noted in states on the East and West Coasts.  Ethanol, another familiar oxygenate and an alcohol derived from corn, is more popularly used in Midwestern states.

The California Department of Health Services is currently working on establishing a primary maximum contaminant level (MCL) of 13 Fg/L (13 ppb) for the chemical and other states are quickly following suit.  If everything remains on schedule for approval, California’s MCL will become effective in the middle of May, 2000.  Until the new MCL is established, they will continue to use 13 Fg/L as an action level. 

The state of Connecticut also regulates bottled water for MtBE with an MCL of 0.5 Fg/L or 0.0005 mg/L.

MCLs can be established at both the state and federal levels.  If a federal MCL exists, state levels may differ; however, local levels may not be higher than federal levels.  At this time, there is no federally established MCL for MtBE.  The EPA is considering adding it to the list of contaminants regulated under the Safe Drinking Water Act (SDWA).  The EPA is attempting to pass regulatory authority to individual states to reduce or eliminate the use of MtBE in gasoline as an oxygenate in their state.  Current regulations under the Clean Air Act require two percent oxygen in gasoline for air pollution reduction for which both MtBE and Ethanol are currently used. 

MtBE is already included in our bottled water annual test packages. 

We have also added MtBE to our WATERCHECK and WATERCHECK WITH PESTICIDES test packages

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