Cuesta Water Main Incident

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About Mountain View's Water Supply

The City of Mountain View continues to perform water quality tests citywide meeting State requirements. The water is safe for drinking and other uses throughout Mountain View. The only exception is for homes in the affected area, located north of Cuesta Park, which have been issued a "Boil Water" notice. 

AffectedArea 04272026

Latest Incident Update

6:00 p.m. Wednesday, May 13, 2026: Cuesta Water Main Incident  

Road Closure Alert During Mechanical Pipeline Cleaning
On Thursday, May 14, the intersection of Drucilla Drive and Montalto Drive will be intermittently closed to general traffic from approximately 7:00 a.m. – 7:00 p.m. Residents living on Drucilla Drive and Carla Court will be allowed to enter and exit through the closure.

The roadway closure will allow for the mechanical cleaning of the pipes—called “pipeline pigging”—along Drucilla Drive and Carla Court. A foam “pig” device, similar in shape to a large earplug, is inserted into the pipe. The device is then pushed through with water pressure. This will be done repeatedly and from several different insertion points. This method of pipeline cleaning is being done to clean out any possible foreign material in the pipe.

Water Sampling Continues
On May 13, the City increased the number of water samples taken and used varied locations, including street-side service lines in the affected area. Test results are expected on Thursday, May 14.

About the Water Main Incident
Currently, 21 homes, located north of Cuesta Park, remain under boil water restrictions until further notice. 

The water main breach involved a private contractor that was hired by the City. The Friday, April 24, incident concerned a contamination breach with some cement slurry mix coming into contact with a live water main near the intersection of Bonita Avenue and Cuesta Drive. 

Questions or Assistance 
For residents in the affected area who have questions, please call 650-903-6081 or email WaterQuality@mountainview.gov.  

For questions specifically about the temporary lodging program, call 650-903-6081 and press 2. 

Stay Informed  
To receive updates via email on the Cuesta Water Main Incident, subscribe to “City News” at MountainView.gov/eNotify

For more information, including resources for residents, visit MountainView.gov/CuestaWaterMain.

Next Update 
The City will issue the next incident update when new information is available.  

Media Inquiries 
For media inquiries, email Communications@mountainview.gov or call Lenka Wright, Chief Communications Officer, at 650-903-6615.

Past Updates

Monday, May 12, 2026 Update
Monday, May 11, 2026 Update
Friday, May 8, 2026 Update
Thursday, May 7, 2026 Updates
Wednesday, May 6, 2026 Update
Monday, May 4, 2026 Update
Sunday, May 3, 2026 Updates
Friday, May 1, 2026 Updates
Thursday, April 30, 2026 Updates
Wednesday, April 29, 2026 Updates
Tuesday, April 28, 2026 Updates
Monday, April 27, 2026 Updates
Sunday, April 26, 2026 Updates
Saturday, April 25, Updates
Friday, April 24, Updates