Advanced treatment processes for potable reuse are essential to the mitigation of microbial and chemical contaminants in reclaimed water. Viruses are a particular focus of water reuse treatment processes because of their acute health effects, low infectious dose, small size, and resistance to disinfection. Therefore, understanding virus occurrence and removal in full-scale advanced wastewater treatment processes for potable reuse application is a high-priority research need. The main goal of this project is to identify and evaluate potential viral indicator(s) for assessing the performance of physical treatment processes during advanced water treatment for potable reuse. Differences in wastewater characteristics, treatment technologies, plant capacities, geographic locations, and seasonal effects will be considered to evaluate virus removal efficiency during soil aquifer treatment, media filtration, activated carbon adsorption, and by integrated membrane systems consisting of ultrafiltration and reverse osmosis. Research partners: California State Water Resources Control Board and Metropolitan Water District of Southern California.