This paper gives a comparative study on the methodology used for the HydroCAD Storm water modeling system (V10) “for the Volume runoff calculations and HydroGraph Analysis” and SewerGEMS (Vi8) Software “for the sanitary sewer design” of the newly developing urban area. The study highlighted the data collection, operating sequence, HydroGraph parameters, pollutant loading steps required for the HydroCAD software users and it gives a user's road map that makes the modeling process simpler overall. The study also emphasises the compatibility of both programmes with AutoCAD and GIS tools, as well as the use of simple calculations to determine runoff peak flows and volumes from a subcatchments. These calculations help users configure, assess, visualize, and compare an infinite number of potential scenarios for the area under study. Both software programmes make it quite easy to build up these computations, which can effectively assist consulting engineers in making decisions.