Direct Potable Reuse: Creating a Responsible & Local Water Source for Silicon Valley

Direct Potable Reuse: Creating a Responsible & Local Water Source for Silicon Valley

Silicon Valley, like elsewhere in California, faces serious water supply issues. Traditional water sources for the region including imported water resources from the State Water Project, and Sierra Nevada snowpack are already stretched thin, and yet the region’s population and development continues to grow, leading to increased demand for water.

Sustainable Silicon Valley is committed to a water resilient Bay Area by optimizing the region’s water resources. This means using existing water resources more efficiently, leading to more demand being met with less water. A viable method of accomplishing this is to implement water reuse, whereby water used by homes and businesses, undergoes treatment, and is then made available again for further use.

“Water Reuse,” is a broad term, which can be used in reference to a number of processes leading to one or more additional uses of a water resource. The focus of this article is on direct potable reuse.

Direct potable reuse (DPR) entails treatment of wastewater to a drinking water quality standard, and reintroducing it directly into the drinking water supply system, or into the raw water supply upstream of a water treatment plant. Due to the high quality of water provided by DPR, its end uses are more diverse than for other types of reclaimed water, and can include industrial, agricultural, landscape irrigation and other municipal uses in addition to drinking water.

Direct potable reuse has the potential to serve a key role in Silicon Valley’s water management puzzle. It makes more efficient use of existing water supplies possible, by allowing water to be used multiple times instead of being discharged after a single use. Keeping water in the system for a longer period would also create a water supply that is both reliable and local, thereby reducing demand for imported water sources, and leaving more water to benefit California’s natural ecosystems. Additional benefits include minimization of wastewater discharges to the environment and lower risk of groundwater overdraft.

Direct & Indirect Potable Reuse Pathways, Photo Credit: University of Arizona

Indirect potable reuse, whereby water recycled to potable standards is allowed to enter the drinking water supply through an environmental buffer, is already practiced in a number of Southern California communities including Los Angeles, and Orange County. In Silicon Valley, the Santa Clara Valley Water District has a demonstration program, which allows people to learn about and taste recycled water. SCVWD is also studying how direct and indirect potable reuse may be implemented for groundwater recharge in the future.

Ultimately, the public will have to embrace the idea of direct potable reuse in order for it to be practiced in Silicon Valley municipalities. For this reason, public education and discussion on the importance of this topic is vital.