The SEDUNIT Project is a Spanish National Research focused on the study of the sediment transport in combined sewer systems.The main objective of this study is to advance in the understanding of the sediment accumulation and erosion processes in combined sewer systems and the optimization of the operation and maintenance practices in sewer networks.The research is divided into three tasks corresponding to different scales in order to approach the objectives of the Project: laboratory tests, field work and numerical modelling.A flume test facility is utilized for the laboratory scale.In this facility, a series of experiments are performed in order to study the accumulation and erosion processes.For the second task, a real combined sewer is being monitored in order to validate laboratory results.The sediment properties and the volume of the accumulated solids in the sewer are the main analysed parameters.The last task consists in a review of the existing sediment transport models and their applicability to assess how parameters such as the cohesion of solids affect the resuspension processes and how they should be included in the existing models.