Occurrence of MTBE in drinking water sources

Methyl tertiary butyl ether (MTBE) is of concern to the drinking water supply profession because of its strong taste and odor effects, potential risk to human health, tendency to migrate rapidly in groundwater, and resistance to conventional water treatment processes. An occurrence survey was performed from 1997 to 1998 to assess the prevalence of MTBE in surface and subsurface drinking water supplies. The survey examined 342 wells in 17 states, and MTBE was detected at least once in 30 wells (similar to8.8 percent). All samples were below the US Environmental Protection Agency's taste and odor advisory level of 20 mug/L. In addition, 92 surface water sites in 12 states were evaluated, and MTBE was detected at least once at eight sites (similar to8.7 percent). The highest concentration (25.1 mug/L) was detected downstream from a known gasoline release. Aeration removed up to 76 percent of low concentrations of MTBE, but activated carbon adsorption was relatively ineffective.