Water Recycling and Reuse Is the Highest-ROI Adaptation

Advanced water recycling — treating municipal wastewater to potable or near-potable standards and reinjecting it into supply systems — is the highest-ROI water infrastructure investment available in water-stressed regions. Orange County Water District's Groundwater Replenishment System produces water at $0.60–0.80/m³ and has operated for 15+ years. Direct potable reuse (DPR), which eliminates the environmental buffer step, is now permitted in several U.S. states and is coming to Texas, Colorado, and California at scale over the next five years. Xylem, Veolia, and SUEZ are the dominant equipment and services providers. The underappreciated technology layer is online water quality monitoring — continuous sensors for trace contaminants that are the regulatory linchpin for DPR permit approval.