The paper explains the causes of climate change and its impact on the rainfall regime over the next decade until 2100. It calculates with three emission scenarios of possible development and draws attention to insufficient water management in urbanized areas, which occurs here in the form of rainfall. Based on the analysis of the precipitation-runoff process in the city of Pezinok created by the EPA software program Storm Water Model Manager (SWMM), it examines the sewer system load and, on the basis of the findings, presents a model solution for how to use this water and mitigate the surface runoff and relieve the sewer system at the time of the rainfall and accumulating rainfall.