Changes in rainfall patterns or land use require flexible adaptation strategies for urban drainage systems. However, finding effective measures to reduce combined sewer overflows (CSO) and flooding is not straight-forward. The presented study proposes a holistic assessment approach that combines CSO quantity and quality criteria with indicators for the spatial extent and severity of flood events. The approach is tested for three selected adaptation measures with a detailed calibrated model of Berlin’s largest combined sewer catchment in the software Infoworks CS. The results indicate that a detailed assessment based on multiple performance criteria is necessary to fully understand measure effects. The presented work is embedded in an integrated modelling study involving different elements of the drainage and the wastewater treatment system.