The Untapped Potential of California’s Urban Water Supply: Water Efficiency, Water Reuse, and Stormwater Capture

Pacific Institute | April 12th, 2022

In this assessment, we quantify the potential for a range of water strategies in urbanized parts of California to both reduce inefficient and wasteful water uses and expa

In this assessment, we quantify the potential for a range of water strategies in urbanized parts of California to both reduce inefficient and wasteful water uses and expand local water supplies. This assessment finds that urban water-use efficiency improvements could reduce statewide urban water use by 2.0 million to 3.1 million acre-feet per year (AFY). The reuse potential of municipal wastewater is 1.8 million to 2.1 million AFY, and the stormwater capture potential is 580,000 AFY in a dry year to as much as 3.0 million AFY in a wet year. Previous assessments have shown that these efficiency and supply options are more cost effective than traditional – and increasingly hard to implement – options to expand supply. Programs to tap this potential would tremendously help solve California’s long-standing water problems.

Toxicological assessment of potable reuse and conventional drinking waters

Nature Portfolio (Springer Nature) | October 27th, 2022

Potable reuse, the process of treating wastewater to drinkable standards, offers a reliable and sustainable solution to cities and regions facing shortages of clean water

Potable reuse, the process of treating wastewater to drinkable standards, offers a reliable and sustainable solution to cities and regions facing shortages of clean water. However, implementation is hindered by perceptions of poor water quality and potential health threats. Herein, we compare water samples from potable reuse systems with conventional drinking waters based on the analysis of Chinese hamster ovary cell cytotoxicity contributed by disinfection by-products (DBPs) and sewage-derived anthropogenic contaminants. In all cases, the cytotoxicity of potable reuse waters is lower than that of drinking waters derived from surface waters. The median contribution to total cytotoxicity was 0.2% for regulated DBPs and 16% for the unregulated DBPs of current research interest. Nonvolatile, uncharacterized DBPs and anthropogenic contaminants accounted for 83% of total cytotoxicity. Potable reuse waters treated by reverse osmosis are not more cytotoxic than groundwaters. Even in the absence of reverse osmosis, reuse waters are less cytotoxic than surface drinking waters. Our results suggest that potable reuse can provide a safe, energy-efficient and cost-effective alternative water supply.