Tri-Valley Water May Stink, But Safe To Drink, Officials Say

ALAMEDA COUNTY, CA — Many residents in Pleasanton, Dublin and Livermore have reported a musty, foul odor and an “earthy” taste of mildew in their tap water since last weekend. Despite the unusual taste and smell, which is produced as a result of algal blooms in the water, officials say the water is safe to drink.

All customers served by Zone 7 are in some way affected and water officials are working to help the improve the taste and odor. Luckily, the foul odor will likely subside within a week or two.

“A large portion of the water provided to our customers is surface water purchased from Zone 7, our wholesale water supplier,” California Water Customer Service Representative Joshua Heavenston told Patch via email. “Zone 7’s source water, supplied by the California Department of Water Resources through the South Bay Aqueduct, has unusually high levels of geosmin, an odor causing compound.”

Water officials say humans are extremely sensitive to the smell of geosmin and Methyl-Isoborneol, which are both currently present in the water due to the proliferation of the algal blooms. The smell is made worse due to the recent heat wave, which helps the algae thrive.

In a 2013 newsletter sent to Tri-Valley customers, Zone 7 officials said they were taking steps to prevent the odor issues in the future. Cal Water officials say Zone 7 is now in the process of upgrading its plants by adding ozone treatment over the next few years, which is the most effective water treatment process in improving taste and odor, but will likely take several years.

“Adding a slice of lemon and/or chilling water can also help to improve the taste of the water,” Heavenston said.

Officials also recommend putting the water in a pitcher and chilling it in the refrigerator to help the smell dissipate more quickly.

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