Methods and systems are provided for disinfecting water mains using ultraviolet (UV) light and advanced oxidation processes. One or more UV light sources are provided and secured to a movable device that moves axially in a pipe. The frequency and intensity of the UV light is determined based on characteristics of the pipe, such as its material and size. The rate at which the movable device moves through the pipe is also determined so that the interior surface of the pipe is properly disinfected. The movable device is remotely caused to move through the pipe. An oxidant supply component having a dispensing portion dispenses an oxidizing agent into the pipe. A portion of the emitted UV light may convert the dispensed oxidizing agent into additional oxidizing agents that further disinfect the pipe.