Earthy taste, smell in Tri-Valley tap water caused by harmless seasonal compound

Residents in the Tri-Valley area may notice an earthy or musty taste and smell in their tap water, but the water remains safe to drink, according to Zone 7 Water Agency. 

The temporary change is caused by geosmin, a naturally occurring organic compound that becomes more common during warm-weather algae blooms in the Sacramento-San Joaquin Delta. The compound affects the taste and odor of water but does not pose a health risk, the agency said.