San Francisco - Non-potable Water Programme


San Francisco is adapting to climate change and the long-term risks of increased drought conditions in California. Eighty-five percent of the San Francisco Bay Area’s water supply comes from melting snows of the Sierra Nevada. As temperatures rise as a result of climate change, the traditional patterns of annual fresh water supply and risks of floods from excess snowmelt will change significantly. The Non-potable Water Programme provides an innovative way to reduce water usage whilst also helping to reduce the risks of flooding from an increase in extreme storm events.
Decentralised water systems are recognised as a method of producing new non-potable water supplies, however, the city is addressing the institutional challenges by creating a regulatory programme for integrating new water systems within existing programmes.


For more than two years, San Francisco has been leading a national effort to partner with other cities to develop streamlined policies that are transferable from state to state. Since then, the city has adopted more than 15 projects to diversify its water supply.


San Francisco is already a national leader in water conservation at 43 gallons per person per day. The programme provides for a new innovative way to further reduce water usage at a building and district scale. By capturing, treating and reusing water onsite, the city can reduce the use of potable water by up to 50% for residential buildings and 95% for commercial buildings. This enables San Francisco to boost water resiliency by extending its potable water supplies for the best use, and decrease the volume of water entering the sewer system during rain events.
San Francisco is helping to pave the way for other cities to create new water paradigms in dense urban cities. Today, many cities in the US and beyond are relying upon San Francisco’s leadership and sharing of best management practices and lessons learned to conduct research and implement strategies within their own complex government structures.

Projected Outcomes

The programme has resulted in positive results to diversify the water supply. To date, fifteen projects have saved more than six million gallons of potable water per year; four projects are underway to offset 33 million gallons; and, with anticipated future developments, another 365 million gallons of potable water will be conserved.
San Francisco’s initiative has high financial and environmental co-benefits. Reduced water demand streamlines the regulatory process for developers thereby avoiding significant costs and delays in building project planning, engineering and delivery. The programme also addresses water shortages and avoids degradation of shoreline water quality. 
Moreover, the programme produces recycled water that has helped to generate new green spaces that results in cleaner air and public health.