A UV disinfection system and methods of UV disinfection are provided. The disinfection system may include a UV transparent conduit to carry a flowing liquid to be disinfected, the conduit having an inlet to receive the liquid and an outlet to discharge the liquid and two or more radiation sources positioned within the conduit substantially perpendicular to the axis of symmetry of the conduit. The walls of the conduit may be coated with a reflective coating acting as a back-surface mirror for enhancing the performance of the disinfection system.