San Francisco Public Utilities Commission
Skip to page body Home Customer Service How To Environment Projects & Programs About Us


BDPL Reliability Upgrade - Tunnel (WSIP)

Project Update

Bay Tunnel Delivering Water to Customers

The new five-mile-long Bay Tunnel is now in service. It forms a lifeline within the Hetch Hetchy Regional Water System delivering drinking water from Hetchy Hetchy, San Antonio, and Calaveras Reservoirs to customers on the Peninsula and in San Francisco. On October 15, 2014, the SFPUC operations brought the new tunnel into service and the SFPUC, together with Bay Area partners, celebrated its completion while watching the first water from the tunnel flow into Crystal Springs Reservoir. This is the first tunnel built under San Francisco Bay, and it replaces aging pipeline infrastructure built in the 1920s and 1930s that traverses the Bay on wooden trestles to provide seismic and delivery reliability after a major earthquake.

The Bay Tunnel Project has been in construction for over four years, and surface restoration work is now underway at the shaft sites. The project reached substantial completion in May 2015.

First water from the Bay Tunnel entering Crystal Springs Reservoir.

Project Description
The new Bay Tunnel will link the existing segments of BDPL Nos. 1 and 2and the future BDPL No. 5 in the East Bay with those on the Peninsula. The existing portions of BDPL Nos. 1 and 2, which were built in the 1920’s and 30’s, lay along the bay floor and on trestles that cross over environmentally sensitive marsh land. The pipe and the trestle are in a deteriorated condition. The Bay Tunnel will bypass these environmentally sensitive wetlands.

The tunnel will extend 5 miles under San Francisco Bay at depths of up to 100 feet and it will be constructed using a specialized Earth Pressure Balance Tunnel Boring Machine.  The excavated diameter will be 15-foot with a final tunnel lining of 9-foot diameter welded steel pipeline. At each end there will be a vertical shaft, and it will connect the BDPL Nos. 1, 2, and 5 piping manifold. The spoils resulting from excavation during this project are anticipated to be used as part of the South Bay Salt Pond Restoration Project, conversion of adjacent salt ponds to marshland. The portion of the existing BDPL Nos. 1 and 2 that are replaced by the tunnel will be capped on each end and will be abandoned in place.

Project Information

    April 2010
    July 2015
  • COST
    $288 Million

Additional Information

The information shown reflects the current forecast information published in the latest WSIP Quarterly Report.

Work Hours

Normal work hours are 7 a.m. to 6 p.m. When tunneling begins, underground work will be 24-hours a day due to project demands. Work will be monitored closely to ensure that noise, light and other disruptions are minimized. Construction is expected to be completed in 2015.

- Bay Tunnel Fact Sheet - Summer 2013
- Bay Tunnel November 2012
- Bay Tunnel Fall 2012 Fact Sheet
- Bay Tunnel Winter 2011 Fact Sheet
- Bay Division Pipeline Reliability Upgrade - Tunnel Project Fact Sheet


Need More Information? Contact

Bay Division Region Hotline
Phone: (800) 571.6610 or