City Hall in Mountain View, Calif., in an August 2024 image. Dozens of households affected by a water main breach may be without potable water until at least Sunday. (Google Earth via Bay City News)

The Mountain View City Council declared a state of emergency after a water main breach this weekend left some households without potable water, the city said Monday.  

The emergency declaration was made on Saturday and the council will ratify the declaration at their Tuesday meeting, the city said. The declaration will allow the city to seek reimbursement from the state and the federal government for expenses related to the incident. 

City crews have been working to rectify the problem after 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. The breach happened Friday when the contractor, C2R Engineering, was performing water main replacement activities at the intersection of Cuesta Drive and Bonita Avenue. 

Residents who have had their water shut off since Friday will have to wait until mid-to-end of the week to be able to use water from their tap for anything other than toilet flushing, the city said.  

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)

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 the maintenance work. Cement slurry got into the system, forcing a shutoff and “Do Not Use” order for any purpose.  

Crews have been flushing the water main and taking water samples for several days. On Monday, the city said two of five water samples the day before tested positive for bacteria. E Coli was not detected but coliform bacteria was found.  

Affected residents have been told that water cannot be used for drinking, cooking, hand washing, bathing or other domestic uses through mid-to-end of the week, the city said.   

In addition to flushing the water main in the street, crews have flushed each affected property’s water service to their front yard, the city said. Crews went to each affected household to provide written guidance on how to flush the indoor house plumbing and answer residents’ questions, as well.  

On Monday, crews conducted more 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.