The City of Napa is committed to providing a safe and reliable supply of drinking water that meets all State and Federal health standards.  The Water Division's three treatment plants transform raw source water into clean and safe drinking water using three basic steps - sedimentation, filtration, and disinfection.  The water supply is continuously sampled and tested for contaminants to ensure that health standards are met and that taste, odor, and appearance are optimized.

Throughout the year, we shift water sources from one reservoir to another and change where water is treated to manage water supplies, adjust for customer water demands, and accommodate emergency or maintenance projects.  These operational changes may occasionally result in customers noticing changes to the taste and smell of their tap water.  Regardless of these seasonal changes, your tap water is safe to drink and currently meets all State and Federal standards.

SPECIAL NOTE:  Annual Hydrant Flushing Program runs from December 11, 2017 through April 2018.  Visit the program's web page for current maps of areas being flushed.


Reporting a Problem with your Drinking Water

Before reporting a problem, please note whether your concern is with the water's color, taste, odor, or something other, and be prepared to answer the following questions:

Call Water Division staff at 707-257-9521.


Annual Drinking Water Quality Report 

As required by law, by July 1 each year the City provides its water customers with a summary of any contaminants detected for the previous calendar year.  The 2016 Drinking Water Quality Report is currently available.  Click on the image to view an electronic version (printable PDF).  Alternatively, hard copies are available at the Water Division, 1340 Clay Street and at the Public Works Department, 1600 First Street.  A primary purpose of the report is to provide detailed information regarding contaminants, related potential adverse health effects, and possible sources of contamination.  Beginning April 1, 2016, all water systems were required to comply with the Federal Revised Total Coliform Rule, monitoring the presence of indicator bacteria naturally present in the environment.  Under this rule, the City was required to conduct a Level I assessment, but no problems were found nor corrective actions required.  In addition, the City met all of the other stringent State and Federal standards for finished drinking water.

If you have any specific questions after reading the 2016 Drinking Water Quality Report, please call the Water Quality Manager at 707-253-0822 or This email address is being protected from spambots. You need JavaScript enabled to view it. them. 


Backflow Prevention

To protect the public water mains from potential contamination by non-potable "used water" that could be drawn in during a sudden pressure drop, the City requires installation of a backflow prevention device on new services.  The device must be approved by the State Water Resources Control Board.  To see the current list of approved backflow prevention devices, stop by the Water Division's 1340 Clay Street office, or contact the State Board's Division of Drinking Water directly at 916-449-5577 to request a copy.  To minimize the visual impact of these devices, consult City of Napa Backflow Screening Guidelines.

All installed devices must be tested annually and immediately repaired if necessary.

        List of Certified Backflow Prevention Testers

For more information, call the Cross Connection Control Program Coordinator at 707-257-9523 or This email address is being protected from spambots. You need JavaScript enabled to view it. them.