Oct 03, 2011

Calif. Officials Declare No Health Hazard From Tap Water With Unpleasant Taste and Odor

Musty taste and smell in drinking water in four southern California counties could persist for weeks

Consumers in portions of four southern California counties may notice a musty taste and odor in their tap water, but it is an aesthetic problem and not a health hazard, according to water quality experts.

Officials at the Metropolitan Water District of Southern California (MWDSC) said the taste-and-odor event is affecting tap water in eastern Los Angeles County communities, as well as Orange, western San Bernardino and southwest Riverside counties. The impacts may vary from region to region, as local agencies blend imported MWDSC water with local supplies.

"The earthy taste and smell stem from an especially large and persistent algae bloom in the east branch of the State Water Project (SWP)," said Jim Green, MWDSC manager of water system operations.

"Metropolitan receives a major portion of its water through the SWP's east branch, which includes Silverwood Lake in the San Bernardino Mountains, and we are working with the state Department of Water Resources (DWR)—which owns and operates the state system—to address the situation," Green said.

Green suggested consumers consider refrigerating drinking water to help improve its taste until the problem diminishes. He cautioned, however, that the problem may persist for a few more weeks.

For the third time in three weeks, DWR water quality experts last Thursday applied copper sulfate to control the algae bloom. Officials stressed that the treated water will be safe for consumers.

The cause has been identified as 2-methylisoborneal, or MIB. The nuisance compound MIB is produced from the growth of certain algae in freshwaters throughout the world. Typically, MIB levels increase when warmer weather accelerates the growth of algae, Green said.

"Unfortunately, MIB is a noticeable needle in the haystack," he added. "People with sensitive taste and smell can detect the compound in water levels as low as 5 ppt. However, water from two treatment plants have experienced MIB concentrations as high as 20 ppt.

"By comparison, one ppt is equivalent to just 10 drops of MIB in enough water to fill the Rose Bowl," Green said.