MTBE In Drinking Water: States where MTBE has been reported in tap water by drinking water utilities
*Low end estimate excludes systems serving over 1 million people. In large systems MTBE contamination typically affects only a portion of the population.
Data were unavailable for some states; other states reported no MTBE detections. Some states currently do not require reporting of MTBE detections.
Source: Environmental Working Group. Derived from data obtained from state agencies under the Federal Freedom of Information Act or state public records laws.
Important Note: A reported detection of MTBE does not mean the contaminant was found at any level in finished drinking water that the water system delivered to consumers. Some results reflect tests conducted on a water source, others may reflect results from finished tap water. MTBE contamination as low as 2 parts per billion produces a harsh chemical odor that renders the tap water undrinkable. For that reason, in the vast majority of the affected communities water utilities have taken steps to protect consumers, often with costly remedial action, as soon as MTBE is detected and before water is delivered. Water utilities either blend contaminated water with clean sources to dilute the MTBE in finished water, install costly systems to remove the chemical, or abandon tainted wells and shift to clean sources. Community water suppliers would be unable to recover the cost of these remedies from MTBE manufacturers under the liability shield Republican leaders have proposed to include in pending national energy legislation.
Data are primarily for community water systems. Comparable data are not available for MTBE contamination of the majority of private wells.