Ultraviolet-chlorine advanced oxidation processes (UV/Cl-AOP) are gaining attention, particularly in potable reuse applications. They also have the potential to aid in the control of taste and odor and other contaminants in conventional drinking water treatment. There is no one comprehensive location containing information on UV/Cl, making it difficult for end users to identify key issues to be addressed and important questions to ask technology manufacturers. This project consolidated information about the state of UV/Cl-AOP in a single reference applicable to utilities, non-expert consultants, and regulators. The project reported on the basic science of UV/Cl-AOP and highlighted practical issues related to implementation and operation. Research partner: California State Water Resources Control Board. Published in 2022.