San Francisco Leading the Circular Water Economy
The circular water economy utilises water reuse and recycling systems to achieve water security. Read how San Francisco is leading the way.
In the circular water economy, reuse is defined as the reuse of water within a single process or the use of harvested water for another purpose without treatment, while recycle is defined as the use of harvested water for another purpose, after treatment. Treatment can be tailored to meet the water quality requirements of a planned use. At the urban level, the circular water economy involves onsite non-potable water systems that are utilised to meet non-potable needs, such as cooling buildings, irrigating landscapes, and flushing toilets and urinals. The benefits of water reuse and recycling include:
- Decreased diversion of freshwater from sensitive ecosystems
- Enhanced resilience to climate change
- Reduced pollution
- Energy savings
San Francisco Leading the Circular Water Economy
San Francisco’s main tools for developing the circular water economy is its non-potable water ordinance and the recycled water ordinance.
Non-potable Water Ordinance
In 2012, San Francisco initiated the Onsite Water Reuse for Commercial, Multi-Family and Mixed-Use Development Ordinance, commonly known as the Non-potable Water Ordinance. The ordinance allows for collecting, treating, and using alternative water sources for non-potable uses in buildings. In 2013, the ordinance was amended to allow for district-scale projects, where two or more parcels can share alternate water sources. Since 2015, the ordinance became mandatory and now requires new development projects over 250,000 square feet or more of gross floor area to install and operate an onsite non-potable water system.
Over the past year, the San Francisco Public Utilities Commission received 21 applications to install onsite water systems, bringing the total projects to over 100. By 2040, it is projected that the total potable water offset by the ordinance will be around 2 million gallons per day.
Some of the local best practices of buildings incorporating onsite water reuse systems include:
- San Francisco Public Utilities Commission headquarters where blackwater is recycled for toilet and urinal flushing, reducing water use by around 60% per annum and saving about 800,000 gallons of potable water each year
- Chase Center, the new sports and entertainment complex in San Francisco, was constructed to collect and treat rainwater, stormwater, greywater, and condensate to meet toilet flushing demands in the arena and two accompanying office buildings. The system offsets around 3.7 million gallons of potable water annually
- Uber’s new office buildings will feature two separate onsite non-potable water systems, collecting and treating greywater and rainwater separately to meet the building’s toilet flushing and irrigation demands. The project will offset about 700,000 gallons of potable water each year
San Francisco’s Recycled Water Ordinance
San Francisco’s Recycled Water Ordinance requires property owners to installed recycled water systems in new construction, modification, or remodel projects. The requirement applies to properties within the designated recycled water use areas and include:
- New construction or significant alterations to a building totalling 40,000+ square feet
- All subdivisions
- New and existing irrigated areas of 10,000+ square feet not constructed in conjunction with a development project
Buildings required to install recycled water systems can use recycled water for all uses approved by the State of California, with some common uses including irrigation and toilet/urinal flushing.
The take-out
Cities can use ordinances to accelerate the development of the circular water economy.
Join the conversation on the following LinkedIn groups: Urban Water Security, Our Future Water, Circular Water Economy, Blue and Green, Nature-Based Solutions, and Urban and Regional Futures
