The Power of Information

National Drinking Water Database

MTBE in California

MTBE (methyl tert-butyl ether) is a fuel additive that had been used as an octane enhancer in unleaded gasoline; it contaminates groundwater due to spillage or leakage at gas stations, and has been banned or scheduled for phaseout in most states.

The Most Polluted Communities in California

27 water utilities reported detecting MTBE in tap water since 2004, according to EWG's analysis of water quality data supplied by state water agencies

Ranked by highest average MTBE level

RankSystem Population Served Positive test results of total reported tests Average Level
1Manana Woods Mutual Water Co
Scotts Valley, CA
3504 of 420.25 ppb
(12 to 37 ppb)
2Cal 20 Village
Upper Lake, CA
15016 of 178.55 ppb
(0 to 21 ppb)
3Riverview Wd
Lakeside, CA
16,000781 of 8557.04 ppb
(0 to 94.5 ppb)
4Tud - Crystal Falls Water System
Sonora, CA
6,41213 of 204.62 ppb
(0 to 11.2 ppb)
5Puerta LA Cruz CC #14
Riverside, CA
1205 of 74.39 ppb
(0 to 12 ppb)
6Cwsc Salinas
Salinas, CA
98,730190 of 3082.61 ppb
(0 to 69.75 ppb)
7City of Daly City
Daly City, CA
92,3116 of 342 ppb
(0 to 35 ppb)
8Yosemite Nps-Hodgdon Meadow
Yosemite National Park, CA
2,5001 of 21.8 ppb
(0 to 3.6 ppb)
9Yosemite Spring Park Util Co
Coarsegold, CA
3,30045 of 711.74 ppb
(0 to 9.4 ppb)
10Crescenta Valley Cwd
La Crescenta, CA
31,00014 of 221.65 ppb
(0 to 6.4 ppb)

Health Based Limits for MTBE

California Public Health GoalsDefined by the State of California Office of Environmental Health Hazard Assessment (OEHHA) as the level of contaminant that is allowed in drinking water. For acutely toxic substances, levels are set at which scientific evidence indicates that no known or anticipated adverse effects on health will occur, plus an adequate margin-of safety. PHGs for carcinogens or other substances which can cause chronic disease shall be based solely on health effects without regard to cost impacts and shall be set at levels which OEHHA has determined do not pose any significant risk to health.13 ppb

Violation Summary for MTBE in California

There are no violations reported for this contaminant in California