Accomplishing OneWaterSF
Matching the Right Resource to the Right Use
Taking Advantage of a High-Quality Local Supply
Groundwater for Drinking
Groundwater, also known as well water, is a renewable source of naturally filtered water found deep beneath the ground surface. San Francisco
sits on the Westside Groundwater Basin and existing wells from this Basin have been the source for irrigating Golden Gate Park for decades.
However, with extensive water quality data from the Basin, we recognize the value of this high-quality water source as a drinking water supply.
The San Francisco Groundwater Supply Project helps diversify our water supply portfolio and reduces our dependence on the Regional Water
System as the only source of drinking water in San Francisco. Simultaneously, we are developing recycled water for the irrigation of green spaces,
ensuring that we are matching each water supply to its appropriate end use. A second groundwater project, the Regional Groundwater Storage
and Recovery Project, will enhance reliability during periods of drought by providing additional groundwater to San Francisco and neighboring
communities when we need it the most.
Re-thinking Rainfall
Rainwater Harvesting
Rainwater harvesting is the practice of collecting and using rainwater from hard surfaces such as roofs for landscape irrigation. A rainwater
harvesting system can range from a small rain barrel to installing a large cistern. Capturing and reusing this relatively clean resource reduces
potable water otherwise used for irrigation and helps reduce runoff from entering our combined sewer system during storm events. Identifying
appropriate end uses for rainwater helps create a more resilient and sustainable San Francisco. Since 2008, the SFPUC has offered a variety
of rebates and incentives to residents to encourage rainwater harvesting. Additionally, the SFPUC has partnered with the City’s Community
Challenge Grant Program to offer Urban Watershed Stewardship Grants for community-based projects that help manage stormwater using
ecologically based strategies, including rainwater harvesting.
Flushing with Recycled Water
Matching the right resource to the right use is a critical Guiding Principal of OneWaterSF. By re-examining all uses of potable water, we can
identify uses where potable water can be replaced with another type of water. One use that has been recently identified is sewer flushing. Sewer
flushing is a critical activity in maintaining and operating a healthy sewer system. Flushing sewers clears debris and built-up blockages in sewer
lines to make sure water keeps flowing to the treatment plant. In 2017, the SFPUC ran a pilot program to use recycled water in lieu of potable
water to flush sewer lines. The pilot demonstrated the feasibility of using recycled water to flush sewers and the need for new sewer flushing
trucks capable of treating water onsite, rather than redirecting staff in the field to return to the Southeast Treatment Plant for recycled water. A
presentation on the pilot’s findings and recommendations for next steps were given to the SFPUC General Manager.
8
Expanding Non-potable Water for Sewer Flushing