A Dissertation Submitted in Partial Fulfilment of the Requirements for the Degree of Master’s in Mathematical and Computer Science and Engineering of the Nelson Mandela African Institution of Science and TechnologyThe storm-water overflow on manhole is numerically solved in this study. To produce a real representation of storm overflow, the Navier-Stokes equations were used. Turbulence flow was modelled using the standard k-epsilon turbulence model together with the volume of fluid method for phase surface tracking. The open-source fluid dynamics tool OpenFOAM 5.0 was used for solving the model and the visualization tool, paraview 5.4.0, was used for processing the solution data. The convergence test was performed at three different mesh sizes. The numerical solution was independent of mesh sizes. The risen storm-water column inside a manhole exerts a non-uniform pressure on the manhole cover. The non-uniform pressure distribution leads to different uplifting forces at manhole cover areas. However, the global uplifting force remains constant as long as the storm-water overflow is happening on the manhole. The overflow intensity is on manhole, and areas opposite to the outlet pipe give the highest intensity of the leaking storm-water. The rate of storm-water column rise inside a manhole is reduced by the use of manholes with larger width (or diameters) and pipes of larger diameters.