Bay Area Water Recycling Should Be More Than a Drop in the Bucket

Bay Area Water Recycling Should Be More Than a Drop in the Bucket

Senator Scott Wiener has introduced a variety of potentially transformative bills for California this year. One of his bills, SB 966, will help advance a new source of recycled water for California, using a method known as onsite non-potable reuse. Onsite reuse systems treat different water sources, like rainwater, greywater and wastewater, at the building site for non-potable uses such as irrigation, cooling towers and toilet flushing. The systems are typically privately funded and can supply up to 90% of a building’s water needs.

Salesforce Tower installed the largest commercial black water onsite non-potable water system in the nation in San Francisco, where there is a permitting and monitoring program for developers and building owners.

This is important because despite having full reservoirs this year, California’s future water challenges are not going away. Last year, California experienced our hottest summer recorded, and it was the third-hottest year for the nation overall. Scientists predict climate change will create even hotter, drier seasons in the future. This impacts both our local water storage and our snowpack, which, as of April 30th, is only at 52% of normal for the state1. This is important as the Bay Area stores most of the water we import in the snowpack. Santa Clara County depends on imported water for 55% of our water supply. Other counties, such as San Mateo, import 90% of their water supply.

In addition to weather pressures, population growth will challenge our water resilience. The Bay Area’s population is expected to increase by 24% in the next 25 years2. Despite improvements in water efficiency appliances, this growth will put further pressures on our water supply.

Northern California is Missing Out On Recycled Water

Recycled water could play a much larger role in Northern California’s water supply, as it is relatively resistant to both drought and population pressures. In Santa Clara County, recycled water makes up only 3 to 5% of our local water supply, and we appear to have a great deal of wastewater that could be recycled. According to a report by Bay Area Clean Water Agencies, we released 510 million gallons of treated wastewater every day into the San Francisco Bay in 2016/2017. This is an increase from 425 million gallons per day during the previous season.3 It is important to note that for a variety of reasons not all of this wastewater can be recycled and some municipalities could face declining flows due to conservation efforts. However, there is still great potential to increase our use of recycled water.

To date, local agencies and municipalities have made centrally treated recycled water a safe source for locations such as Levi’s Stadium, San Jose Airport, large businesses and golf courses. However, quickly expanding recycled water production and distribution is challenging. New facilities are expensive and can take many years to fund, design, permit and build. Laying recycled water conveyance pipes (“purple pipes”) under our built urban centers can be disruptive and expensive, with current costs of $1 to $3 million per mile.

The Many Benefits of Onsite Non-Potable Water

Installing onsite non-potable reuse treatment systems in new buildings can be done much more quickly, with little cost to ratepayers, and will provide more businesses and large multi-family housing access to recycled water. San Francisco has over a dozen onsite installations, with many more in the permitting process, including a system at the new Salesforce Tower.

San Francisco’s success is due to San Francisco Public Utilities Commission’s (SFPUC) onsite reuse program, which guides applicants through the necessary steps for designing, building and operating systems. In fact, after the program was created, the San Francisco Board of Supervisors passed an ordinance requiring systems in most buildings over 250,000 square feet.

While onsite systems are sprinkled throughout California, most cities lack permitting programs like San Francisco’s. This makes for a costly and unpredictable process for building owners and developers to obtain a permit. Outside of San Francisco, the local permitting process can take up to three years for large systems, with no guarantee of a permit in the end.

181 Fremont Tower, a unique sustainability in a high-rise project, includes a non-potable water system to capture, treat, and reuse graywater and rainwater.

SB 966 Will Encourage the Adoption of Onsite Systems

SB 966 can reduce the friction for onsite reuse adoption by requiring the State Water Resources Control Board to provide guidance for cities to create custom permitting programs. The bill will also provide state quality standards so municipalities can be confident the systems are protective of public health. This will ensure there is guidance and predictability in designing, permitting, installing and operating onsite systems of the highest quality.

Onsite systems can contribute to our water supply, decrease demand for fresh water from our streams and rivers and reduce the treated wastewater we release to the bay. This can increase our water resilience for our entire community–for businesses, residents and aquatic ecosystems. In sum, SB 966 can help cities create a safe, efficient path forward for new partners to contribute to a more secure water supply for the entire community.


1 California Department of Water Resources
2 Department of Finance, State of CA
3 BACWA 2017 Annual Report