Agriculture accounts for the vast majority of water use in California, yet treated wastewater that could irrigate crops is often discharged without use, due to regulatory barriers. Metropolitan partnered with the Pacific Institute to investigate obstacles and develop a practical guidebook grounded in real case studies to help water managers, regulators, and farmers overcome them. The research found that the most successful reuse projects deliver multiple benefits, such as irrigation enhancement and nutrient management, through early partnerships with stakeholders, providing a replicable model for expanding agricultural reuse.

Metropolitan’s Turf Replacement Program offers cash rebates to homeowners and businesses that replace water-intensive traditional lawns with drought-tolerant native plants, but their full effect had not been measured. Dr. Andrew Marx of PlanetScape AI used aerial imagery to track nearly 800 homes across 20 neighborhoods, measuring how many non-rebated households converted their lawns after seeing a neighbor do it. The research found that for every 100 rebated conversions, an additional 132 nearby homes followed suit, thereby more than doubling the program's water-saving potential.

As Southern California increasingly looks to recycled wastewater as a drinking water source, water agencies need to understand how wastewater treatment affects the performance and cost of advanced purification. Metropolitan partnered with Carollo Engineers and the California State Water Resources Control Board to examine how different wastewater treatment conditions influence downstream purification processes and finished water quality. The research produced a ‘cause-and-effect database,’ a decision support flowchart, and case study documents to help agencies identify the most effective and economical path to potable reuse.

Viruses are a top concern in potable water reuse due to their small size and resistance to disinfection yet water agencies lacked reliable methods to confirm that advanced treatment processes were removing them effectively. Metropolitan partnered with researchers at the University of Arizona to identify and evaluate viral indicators that could serve as proxies for assessing performance across a range of physical treatment technologies. The findings give water agencies and regulators a practical framework for confirming that potable reuse systems are meeting safety standards across diverse operating conditions.