This paper concerns the experimental and numerical analysis of the hydraulics of flushing waves. In particular, it reports the results of the experiments performed at the laboratory of Hydraulics of the University of Catania by using scale models of flushing gates and aimed at the study of both the outflow processes of the gates and the propagation of the waves generated by the devices. Furthermore, this paper describes the set-up of numerical models for the simulation of the operation of flushing gates and the propagation of flushing waves and presents the results of the application of the models to the laboratory data and the data derived from an experimental campaign conducted in a real sewer channel of Lyon, France.