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)

Residents in Mountain View affected by a water main breach last week may not have potable water until at least Sunday, the city said Wednesday.  

“At this time, the city of Mountain View is preparing for the possibility that the clearance by the California State Water Resources Control Board to restore drinking water will not happen before Sunday, May 3,” the city said in a release. 

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 on Friday, according to Lenka Wright, a City of Mountain View spokesperson. The breach happened when the contractor, C2R Engineering, was performing water main replacement activities at the intersection of Cuesta Drive and Bonita Avenue.  

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)

The Mountain View City Council declared a state of emergency Saturday, which will allow the city to seek reimbursement from the state and the federal government for expenses related to the incident.  

Affected households have only been unable to use water from their tap for anything other than toilet flushing, the city said. Water cannot be used for drinking, cooking, hand washing, bathing or other domestic uses.  

Wright said that the water shutoff was due to cement slurry getting into the system, forcing a shutoff and “Do Not Use” order. 

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.   

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 household to provide written guidance on how to flush the indoor house plumbing and answer residents’ questions, as well.   

Mountain View will hold a neighborhood meeting Friday for residents affected by water main contamination, all of whom will receive direct invitations, the city said.  

The city is also collecting information from affected residents to provide reimbursement for meal and incidental expenses at federal per diem rates of $92 per day per resident. Temporary lodging remains available through Monday at several hotels in Mountain View and nearby Sunnyvale, and residents who choose other accommodations may be reimbursed up to $192 plus tax per night, city officials said.  

Residents may also continue using shower facilities at the Rengstorff Park Aquatics Center and Eagle Park Pool while the city explores expanding access to more facilities. 

More information and resources for residents can be found at mountainview.gov/CuestaWaterMain.  

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.