A water main break in the city of Mountain View, Calif., on Friday, April 24, 2026, left 67 households without usable tap water for at least the next two days. The break impacted residents in the Cuesta Park neighborhood. (City of Mountain View via Bay City News)

Mountain View residents who have had their water shut off since Friday will have to wait until at least mid-week to be able to use water from their tap for anything other than toilet flushing, the city said Sunday.  

About two thirds of the residents in Mountain View’s Cuesta Park neighborhood had their water restored on Sunday morning for toilet use only and will have to contend with that until city crews can render the water potable.  

About 67 households in the 600 block of Cuesta Drive and 600-700 block of Leona Lane had water shut off due to a breach of a water main during maintenance work, according to Lenka Wright, a City of Mountain View spokesperson.  

Wright clarified Sunday that the water shutoff was not due to a water main break but due to contamination that got into the pipeline during maintenance work involving the replacement of a portion of the main by a contractor. Cement slurry got into the system, forcing a shutoff and “Do Not Use” order for any purpose.   

Water cannot be used for drinking, cooking, hand washing, bathing or other domestic uses through mid-to-end of the week, the city said.  

According to the city, the extended timeline for restoring safe drinking water is due to two of the five water samples coming back positive for bacteria. Crews are resuming flushing activities with the intent to rid the isolated system of the bacteria.  

On Sunday night and Monday morning, the City of Mountain View water utility crews will follow State Water Resources Control Board’s instructions to conduct additional comprehensive drinking water safety testing, the city said. 

Impacted residents have been offered free hotel stays and were delivered bottled water, according to the city.  

Potable water is available at the Cuesta Park restrooms and picnic area. Residents should bring their own container that is no more than 5 gallons. 

For assistance, affected residents can call 650-903-6081 or email WaterQuality@mountainview.gov. 

Katy St. Clair got her start in journalism by working in the classifieds department at the East Bay Express during the height of alt weeklies, then sweet talked her way into becoming staff writer, submissions editor, and music editor. She has been a columnist in the East Bay Express, SF Weekly, and the San Francisco Examiner. Starting in 2015, she begrudgingly scaled the inverted pyramid at dailies such as the Vallejo Times-Herald, The Vacaville Reporter, and the Daily Republic. She has her own independent news site and blog that covers the delightfully dysfunctional town of Vallejo, California, where she also collaborates with the investigative team at Open Vallejo. A passionate advocate for people with developmental disabilities, she serves on both the Board of the Arc of Solano and the Arc of California. She lives in Vallejo.