Sunday, May 3, 2026: Cuesta Water Main Incident

3:55 p.m. Sunday, May 3, Update: It's now Day 10 since a water main contamination emergency began impacting 67 homes in the neighborhood north of Cuesta Park. This localized area remains under a "Boil Water" notice. Outside the affected area, the water is safe for drinking and other uses throughout Mountain View. See map below.

Water Quality Testing Update
The latest water tests have come back positive for low levels of coliform bacteria in one area of the affected neighborhood where the private contractor, hired by the City of Mountain View, installed a new pipe as part of a water main replacement and upgrade project. The latest water tests remain negative for E. Coli.

At this time, the positive test results appear to be concentrated in the water line serving homes on Drucilla Drive and Carla Court.

The City, in coordination with regulatory partners, is actively evaluating a range of potential remedial actions to fully restore safe drinking water to the affected area.

Latest Timeline for Boil Water Notice for Affected Homes
In close coordination with the California State Water Resources Control Board, the City does not anticipate fully lifting the "Boil Water" restrictions for the affected homes before the weekend of May 9 and 10.

The City will continue to provide resources to the affected residents, which include temporary lodging if needed; temporary shower access at the El Camino YMCA, Rengstorff Park Aquatics Center, and Eagle Park Pool; drinking water delivery service; and meal and incidental expenses reimbursement ($92 per day plus tax per resident; receipts are not needed for meals and incidentals).

The City thanks the affected residents for their patience and understanding during this challenging time. Rest assured, all City resources available for this localized emergency are being dedicated to restoring safe drinking water services to the affected area as soon as possible.

Boil Water Notice in Impacted Area
The "Boil Water" Notice is in effect for the affected area, north of Cuesta Park, until further notice.

For affected residents, here is a list of do's and don'ts for tap water usage, after their household plumbing has been flushed, in accordance with the "Boil Water" notice instructions:

What you can do with water from the tap:

• Take a bath and shower
• Wash hands
• Use laundry machine for washing clothes
• Run a dishwasher

What you can do with water that has been boiled following "Boil Water" notice instructions:

• Drink and cook
• Prepare other drinks (coffee, tea, lemonade)
• Wash produce
• Wash food prep areas
• Make ice
• Brush teeth

Tap water that has not been boiled for at least 1 minute should not be used for drinking and cooking.

For more information, view the State Water Control Board's Fact Sheet on What to Do During a Boil Water Advisory.

About the Water Main Incident
The water main breach involved a private contractor, C2R Engineering, 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 [email protected].

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 [email protected] or call Lenka Wright, Chief Communications Officer, at 650-903-6615.