San Francisco requires all new large buildings to treat their non-potable water on-site, reducing the use of potable water and conserving the region’s scarce resources.

The Challenge

By 2050, based on current per-capita water use, California’s estimated 22 million additional residents will need an additional 6.8 billion m3 of potable water per year. As California sees longer-lasting droughts and increased urbanization, San Francisco’s Non-potable Water Program anticipates an increase in the number of on-site water treatment systems installed, making it a critical strategy for dealing with a shrinking water supply due to climate change.

The Solution

San Francisco’s Non-potable Water Program allows buildings and districts to incorporate decentralized, on-site water systems. Collecting and treating non-traditional sources of water, such as rainwater, stormwater, blackwater, and graywater, can reduce the use of potable water by up to 50% for residential buildings and 95% for commercial buildings. The collected water is used for irrigation of green surfaces, toilet flushing, and other non-potable uses. San Francisco’s program is designed to streamline the process for the private sector and create a new water management paradigm within the city.

The program began in 2012 as a voluntary measure, but, as of 2015, it became mandatory for all new buildings over 23,000 m2 to recycle water on-site, making it the first policy of its kind in the USA. This groundbreaking step ensures that all new developments in San Francisco are built with water conservation as a top priority. Since the program’s inception in 2012, 33 projects have installed on-site water reuse systems.

Social Benefits – On-site water systems build water resilience and enable communities to sustainably utilize available water resources to withstand and recover from adverse situations.

Economic Benefits – The program provides grants of up to $500,000 to projects implementing on-site water reuse systems

Health Benefits – The program regulates the entire life-cycle of water recycling installation systems, guaranteeing safe operation and usage and the protection of public health.

About Cities100

Presented by C40 Cities Climate Leadership Group (C40), Sustainia and Realdania – Cities100 showcases leading solutions to urban climate challenges in ten sectors, ranging from solid waste management to transportation.

Available online and in print, Cities100 provides stakeholders an accessible format to explore achievable solutions for climate action in cities, and will be a useful tool for relevant groups ranging from impact investors and development organizations, to mayors and city governments.  You can access the full Cities100 2015 publication online here.

  • Economic
  • Health
  • Social
Key Impact
91 million liters of potable water saved each year since 2012
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