Appraisals results of divided and combined rain sewers highly depend on the appropriate choice of model rain. The goal of this research is to verify the impact of different rain models on results of rainfall totals, calculated flow in the network and in their overall effect on the assessment. This research focuses on three main rain models - block rain (reduced), a synthetic rain and actual historical rain with data collected from meteorological stations allocated in the area of Vrable. Historical rain event for the area has been chosen as the one with highest overall intensity with duration of at least 1 hour. Modeling process has been conducted in interface of MIKE URBAN software.