The San Francisco Public Utilities Commission’s headquarters in downtown San Francisco, shown in the above photo, uses 65 percent less water than other buildings of similar size. 

The 13-story building is a big step towards sustainability, right up there with water efficient landscaping. But the best part of this story is what has happened since the completion of the building in 2012. The City and County of San Francisco are taking water conservation to a new level.

The building captures rainwater from its roof, stormwater at its base and the nuisance groundwater that drains into its foundation and uses the water for irrigation. Most of the water savings, however, come from recycling the wastewater from the sinks and toilets on each floor.

The wastewater is treated on-site in a system called a Living Machine®. Solids are removed in a primary treatment tank and put in the sewer. Then the water moves through a series of basins that mimic tidal wetlands. The basins are flooded and drained to create multiple tidal cycles each day, producing reusable water that is treated with ultraviolet light and chlorine and pumped back into the building’s toilets.  All people see are the tops of the wetland plants next to the sidewalk.

The Living Machine® recycles up to 5,000 gallons of water per day and is expected to save the SFPUC $118 million over the next 75 years. And, the treatment, plumbing and rainwater harvesting systems added less than one percent to the cost of construction.

Diagram of SFPUC Headquarters Building's Living Machine onsite wastewater recycling system.

Within a year after the completion of the building, the City and County of San Francisco adopted an ordinance allowing for the onsite collection, treatment, and use of alternate water sources, released the Non-Potable Water Program Guidebook and a grants program for developers, and established a collaborative working relationship between the SFPUC and the departments of Public Health and Building Inspection to oversee developers.

Developers have embraced the program. The March 2016 update of San Francisco’s Non-Potable Water System Projects showcases 13 completed developments throughout the city and lists 14 future developments not yet under construction. Beginning November 1, 2016, the city and county will require all new building projects with 250,000 or more square feet of floor space to use available alternate water sources for toilet and urinal flushing and irrigation.

The SFPUC went one step further. In 2014, they hosted states, cities and research foundations to a two-day discussion on overcoming institutional barriers to onsite water treatment. The group developed the Blueprint for Onsite Water Systems: a Step-by-Step Guide for Developing a Local Program to Manage Onsite Water Systems, a how-to guide to help other cities and communities repeat San Francisco’s success.

Click on the links below to learn more:

San Francisco’s Non-Potable Program

Innovations in Urban Water Systems