Chattogram is the port city as the busiest port of Bangladesh is there. Geographically, it lies besides the Bay-of-Bengal and Karnaphuly river. The city is currently stuck with urban flood and water pollution. Drainage congestion results in irregular flow of water which then ended in urban flood. Urban flood carries huge number of pollutants from the drains to the other water bodies. This study aims to investigate drainage congestion as the causal factor of urban flood and urban flood is the cause of water pollution. This study also aims to assess the impacts of water pollution in the study area. The findings highlight that drainage congestion causes irregular water discharge and overflow of water. A short time to rain results as the urban flood in the study area. The water of drainage system gets mixed with the urban flood which then carried into the karnaphuly river, lakes, khals, canals, ponds etc. The pollutants from the drain cause the water pollution. Study found that the drainage water is much more polluted in comparison to normal water quality parameters. The amount of pollutant is much more because of drainage congestion as the congested water gather much pollutants than the natural flow of water. Statistical analysis also found the significant correlation between drainage congestion and water pollution. However, the residents of the study area are the much more sufferers of the water pollution. They fall a victim to Cholera, Typhoid, hepatitis B, Dysentery, Dengue, Chikonguniya etc. water related diseases. Impacts on urban neighborhood as impacts on aesthetic beauty, impacts on drinking water, impacts on human habitat, impacts on environment, infrastructural impact, spread out of diseases among the residents etc. were found in this study. Impacts on urban environment as impacts on soil, impacts on atmosphere, impacts on human habitat, impacts on human health, impacts on road and other infrastructures etc. were investigated as well. This research also came up with the possible solution to mitigate the impacts of urban flood and water pollution in the study area.