Making Onsite Water Reuse the Norm in California

Alliance for Water Efficiency and SFPUC are Imagine H2O's Water Policy Challenge Winners.

California’s conventional water and wastewater infrastructure is under pressure—conditions exacerbated by declining water availability, drought, and population growth. To tackle the challenges ahead, we need to unlock new ways to collect, treat and reuse local water resources. Onsite water treatment and reuse is a largely untapped opportunity to stretch the state’s public water supply.

By enabling multiple reuse of water onsite and determining what quality of water is needed for what purpose—fit for purpose as it’s called—we can collect and treat a range of alternate water sources already available to us but currently wasted. Whether it’s using greywater for flushing toilets or repurposing stormwater for landscaping, California’s commercial and residential buildings can capture this water, and following treatment, use it for their own non-potable water needs.

The technologies to enable delivery of different water quality levels on-site to meet residential, commercial and industrial uses already exist. They are widely available and in operation around the world. So why have haven’t seen its widespread deployment in California?  The winning entry to Imagine H2O’s inaugural California Water Policy Challenge, a joint proposal submitted by Alliance for Water Efficiency (AWE) and San Francisco Public Utilities Commission (SFPUC), is confronting that very question head-on.

“Treating water for all end uses to uniform Safe Drinking Water standards, and then discharging the water after only one use, is not a sustainable strategy for California’s future,” says Mary Ann Dickinson, President and CEO of AWE. “Our vision stretches water supplies by removing the policy barriers to continued reuse of water onsite, thereby enabling the collection and treatment of graywater, rainwater, stormwater, foundation drainage and black water.”

The team offers a statewide policy framework for onsite water systems in commercial, multi-family and mixed-use buildings. By providing guidance on performance and water quality standards, monitoring regimes and public health criteria, the team hopes to bridge the persistent gap between regulation and innovation in this area. The team’s progress speaks to the appetite among stakeholders to get this right, from real estate developers to regulators to public health officials. 

“We have the experience and know-how to develop an onsite water system policy that allows for the broad adoption of treatment technologies,” says Paula Kehoe, Director of Water Resources with SFPUC. “We are conducting research to address some of the public health concerns associated with onsite water systems.”

SFPUC has been at the forefront of this issue for quite some time. It developed a local ordinance in 2012 that allows for the collection and treatment of alternate water sources in buildings in San Francisco. The next step for the SFPUC is to prepare the technical criteria in coordination with national public health experts.  AWE and SFPUC want to see a statewide policy to assist communities across California. By engaging a full range of stakeholders in the process, including the State Water Resources Control Board, water utilities, environmental groups, plumbing trade groups, builders and developers, among others, the team hopes to inform a transparent and predictable regulatory framework to get onsite treatment systems deployed at scale.  

SFPUC and AWE want to see this innovation replicated in decentralized systems in California—a bold vision for the future of California water. As a winner of the inaugural Challenge, AWE will receive up to $25,000 in support to move forward.

To learn more about the project, please contact Paula Kehoe at (415) 554-0792 or To be involved in stakeholder outreach, please contact Mary Ann Dickinson at 773-360-5100 or