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  • Suresh Venkatraman

Smell The Coffee? Because The Water Smells Like “Geosmin”.

A message from Santa Clara Valley Water District:

If you have noticed an earthy smell in your tap water, we want you to know that we are aware of it and are working to correct the odor that, while unpleasant, does not pose a health concern.

The smell is affecting parts of Santa Clara, Sunnyvale, Campbell, Saratoga, Monte Sereno, Cupertino, Mountain View, Los Altos and Los Gatos, and to a lesser extent south San Jose, and is purely aesthetic. Our water still meets or surpasses drinking water standards.

The earthy odor is caused by geosmin, a compound produced by algae that has recently bloomed in the Sacramento-San Joaquin Delta and the San Luis Reservoir, where the water district gets more than half of the water it supplies to northern Santa Clara County. Geosmin is not an algal toxin, so the safety of the water is not impacted. However, the human nose is very sensitive to geosmin: some people can smell it at extremely low levels – as low as 1.3 parts per trillion (ppt). Levels up to 48 ppt have been measured in the source water and treated water.

At present, we expect the intense geosmin odor to subside in a few days as the water already in the distribution system works its way out. We have changed the source of water at our Rinconada and Santa Teresa water treatment plants to a local reservoir that has not been affected by the same odor. We are also increasing treatment at our three water treatment plants to rid our treated water of the unpleasant smell.

As we work to mitigate geosmin’s effect on our water, customers who do experience a taste or odor can chill their tap water before drinking in order to make taste and smell issues less noticeable. It is not necessary to boil water as the water is safe to drink and meets all state and federal public health standards.

The water district will strive to improve the taste and smell of the water in this unusual time. We put the highest priority on providing safe, clean water to Santa Clara County.

Learn more about taste and odor issues at

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