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Seasonal Changes May Impact Water Odor, Taste

A lake reflects the tree-lined hillsides of the Mount Tamalpais Watershed.

Update on potential for water differences - Aug. 26, 2022

Occasionally, during the warmer months, some customers experience a different taste or odor in their drinking water. Some describe the water as tasting and smelling earthy, musty, or moldy. This is caused by naturally occurring compounds produced by algae in our reservoirs. Algae are a natural phenomenon, particularly during the warm summer months, and are a reminder that our lakes are living water bodies.

During certain times of the year, we may also shift water sources from one reservoir to another to manage our water supply. These operational changes can result in customers noticing changes to the taste and smell of their tap water. These slight changes, which are common in lake water, do not affect the safety of your water. Your water is treated and meets or exceeds all state and federal requirements.

For those who are more sensitive to taste and odor changes, chilling the water during these periods will help reduce the temporary change in taste or smell of your water. For questions or for more information, visit or contact us at or at 415.945.1550.