Nowadays, considering the urban facilities and infrastructure development, utilization and maintenance are very important for many reasons. In this regard, the management, collection, and disposal of sewage and rainwater are very noticeable. The lack of surface water collection networks-being one of the most crucial urban facilities and infrastructure-along with the old swage network caused many health problems for citizens in some cities in the country. This study has been conducted to investigate the effects of lack of surface water collection and disposal networks in Ahwaz City. In the present research, the occurrence of floods and rainfall effects on the sewage accidents and drainage was examined using data in 2018 and 2019. The results show that the amount of swage drainage increased with increasing rainfall and it depends on rain intensity and duration. Due to the design of Ahvaz sewerage network separately, rainwater entering the network has caused damage and dissatisfaction of citizens and the design and implementation of surface water collection network is necessary to increase efficiency and reduce maintenance costs of sewerage network.