How Drinking Water Powers San Francisco

San Francisco’s delicious Hetch Hetchy tap water is famous, but what few people know is that this water also powers the City.

The same force of gravity that propels Hetch Hetchy water across California and to your tap is also harnessed to generate clean, 100% greenhouse gas-free Hetch Hetchy hydroelectric power. Hetch Hetchy hydroelectric power is used to power city services such as MUNI, SFO, fire stations, schools, streetlights, museums, parks and more throughout San Francisco, in addition to homes and businesses at the San Francisco Shipyard and on Treasure Island, and elsewhere in the City. In fact, water from the Hetch Hetchy Reservoir powers about 17% of the City’s electricity needs.

Board of Public Works, Hetch Hetchy, Powerhouse at Early Intake, East end.

About 150 miles East of San Francisco, the City operates three hydroelectric powerhouses: Moccasin powerhouse, Kirkland Powerhouse, and Holm Powerhouse. The total combined hydroelectric generating capacity for these facilities is 385 megawatts, and they produce an average 1.5 billion kilowatt hours of clean hydroelectric energy each year. The energy is generated from gravity-driven water flowing downhill through enclosed pipes called penstocks, which then turns turbines inside the powerhouse and is fed into transmission lines for delivery to customers.

OShaughnessy Dam completed.

In addition to hydroelectricity, the City also adds electricity generated from solar and biogas to the Hetch Hetchy power mix. The San Francisco Public Utilities Commission (SFPUC) operates the City’s 20 municipal solar arrays across rooftops on City buildings, such as Moscone Center, City Hall, Davies Symphony Hall, and schools. The SFPUC also operates a cogeneration facility at the City’s Southeast Waste Water Treatment Plant. This plant takes methane gas that is generated as a by-product of the City’s water treatment to fuel an on-site generator to create renewable energy and significantly reduce overall greenhouse gas emissions.


San Francisco benefits immensely from owning and operating the Hetch Hetchy Power system. Hydroelectric energy is cost-effective and 100% greenhouse gas-free. It does not produce any harmful radioactive byproducts or leave behind waste. Hetch Hetchy Power keeps our environment clean and helps the City meet its sustainability goals.

Board of Public Works, Hetch Hetchy Aqueduct, Supervisor’s party at Early Intake Dam.