WATER SECURITYCalifornia’s Best New Source of Water? Reuse.

By Caroline M. Reinhart

Published 16 March 2023

While expensive solutions like new reservoirs and seawater desalination grab attention, California communities are quietly building up their capacity to clean stormwater and wastewater for reuse for irrigation, industry and, yes, drinking water too.

As California has struggled with drought, Governor Gavin Newsom’s fundamental solution: find more water by diversifying the state’s public water supply. Because of the proximity of the Pacific Ocean, one of the most frequently mentioned sources is seawater desalination. A few communities are trying it, despite environmental concerns. 

But another potential source gets less public attention, even though water providers are showing increasing interest thanks to its early successes: reuse.

“In many regions we’re running up against limits on natural water availability of the traditional sources of supply,” said Peter Gleick, the co-founder of the Pacific Institute, an environmental research organization. “And when that’s the case, and when you want more supply, you have to think about alternatives. The best, most reliable alternative is treated wastewater.”Californians use approximately 6.6 million acre-feet of water per year in urban areas. To meet this demand, the state’s water utilities identified a range of options including recycled water, desalination, and conservation. 

Using less water is the quickest, cheapest and easiest alternative. “Conservation is still one of the biggest things we can do,” said Mehul Patel, the executive director of operations for Orange County Water District’s Groundwater Replenishment System. “Use less, be smarter, think about why we’re using the water we’re using and the volumes we are using it. That would go a long way.” But reused water may be the next best option.

The New Goal: Doubling the Volume of Reclaimed Water
Reclaimed water is largely used in two ways: first, for industrial machines, irrigation, and agriculture and second, for eventual human consumption after treatment and a period of retention time in an aquifer. These types of reuse, non-potable and indirect potable reuse, already supply approximately 728,000 acre-feet of reused municipal wastewater in California per year. This constitutes 11 percent of total public water system use, and uses less than a quarter of the state’s wastewater leaving room for considerable growth.

According to the Pacific Institute, California has the potential to increase their water supply by an additional 1.8 to 2.1 million acre-feet per year if they expand water reuse. Newsom’s reuse goal, 1.8 million acre-feet by 2040, would double the amount of recycled water used in 2021.