Adapting For Climate Resilience
California is no stranger to the effects of climate change. Since 2020, we’ve seen the driest three years in the state’s history followed by equally impactful storms. As the weather becomes more extreme and less predictable, the San Francisco Public Utilities Commission (SFPUC) is rethinking the way we use water and the sources of supply available to us.
The traditional approach to water services incorporates large-scale centralized systems with extensive piping networks. The SFPUC’s core infrastructure follows this model, operating over 150 miles of pipeline to transport surface water from the Sierra Nevada to the agency’s 2.7 million customers in the Bay Area. Once distributed to homes and businesses, water is then treated and discharged as wastewater into the bay or ocean. This linear approach became common practice in the 19th century. Today, challenges such as climate
change, population growth and new regulations present new risks to a centralized system which depends on supplies from rainfall and snowmelt. To meet future challenges, the SFPUC is reimagining new systems that can complement our existing water infrastructure and present opportunities to mobilize local communities. Localized, or decentralized, systems that support water reuse are one example.
The SFPUC’s Onsite Water Reuse Program helps buildings establish their own localized system to capture and treat rainwater, blackwater and greywater for non-potable applications like toilet flushing, irrigation and cooling towers. Onsite water treatment systems embody the principle of fit for purpose to treat water to the appropriate level that is needed for its end use. These systems can reduce potable water use up to 45% in residential buildings and up to 75% in commercial buildings.
Onsite water reuse can also have benefits outside of providing non-potable water supplies. This includes reducing energy needs to pump water, producing thermal energy, reducing capital expenditures and engaging the community, civil society and corporations in water management.
Paula Kehoe is the director of Water Resources at the San Francisco Public Utilities Commission and the chair of the National Blue Ribbon Commission for Onsite Non-Potable Water Systems.
