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Mar 21

Operational error by SFPUC results in untreated water entering the regional water system

Posted on March 21, 2015 at 11:51 am by Clay Curtin

On Tuesday, March 3, 2015, an operational error by the San Francisco Public Utilities Commission (SFPUC), resulted in a valve being left open which allowed a limited amount of untreated water from the SFPUC’s San Antonio Reservoir in the East Bay to enter into the treated San Francisco Regional Water System, and to subsequently enter the Menlo Park Municipal Water District. Although this is not, and was not, an emergency, as our customers, you have a right to know what happened and what we are doing to correct this situation. A letter is being sent, under the direction of the State Water Resources Control Board Division of Drinking Water, to approximately 3,500 Menlo Park water customers who may have received this blend of water.

There is nothing that our water customers need to do at this time; there is no need to boil your water or take other actions. This is not, and was not, an emergency. If it had been, you would have been notified immediately. The untreated water was blended with already treated water before reaching any customers, providing some disinfection treatment. The SFPUC has since released the remaining water into its Peninsula reservoir, where it will be treated before future delivery to water customers. The San Antonio Reservoir is a highly protected drinking water reservoir with no public access. Two years of water quality data, including additional samples taken promptly after the incident confirm the absence of pathogens of concern like Cryptosporidium and Giardia.

The SFPUC is conducting a thorough investigation and will work with its regulatory agency, the SWRCB Division of Drinking Water, and wholesale customers, including MPMWD, to prevent any future occurrences. For more information, about your water quality or service please contact Pam Lowe at 650-330-6750 or email For more information about the incident in the Regional System, please contact the SFPUC at: 866-973-1476.