October 22, 2003

MTBE In Drinking Water: States where MTBE has been reported in tap water by drinking water utilities

State Number of
Systems Affected
Total 1,512 14,915,000 to
Alaska 1 36,000
Alabama 9 282,000
Arkansas 129 486,000
California 127 30,989,000
Delaware 15 78,000
Florida 11 629,000
Iowa 3 3,000
Illinois 29 218,000
Indiana 14 192,000
Massachusetts 221 2,212,000
Maryland 119 195,000
Maine 15 21,000
Michigan 14 66,000
Minnesota 4 17,000
Missouri 13 17,000
Nebraska 8 11,000
New Hampshire 280 390,000
New Jersey 138 2,120,000
New Mexico 5 39,000
Nevada 3 83,000
New York 170 455,000
Ohio 5 9,000
Oklahoma 13 6,000
Pennsylvania 46 969,000
Rhode Island 28 84,000
South Carolina 16 60,000
Texas 47 919,000
Wisconsin 29 229,000


*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.