Currently, most conservation authorities and municipalities in Canada are moving toward encouraging and even mandating the use of Low Impact Development (LID) practices for stormwater management. Understanding the performance of LIDs is very important for their evaluation against minimum stormwater management criteria; hence, in the approval process of new developments. The objective of this study is to better estimate the pollutant removal efficiency of infiltration based LIDs, such as bioretention cells, permeable pavements, dry swales, etc., using numerical simulation. A model is developed, which incorporates each unique site’s characteristics into its calculation of the runoff treatment, including removal of Total Suspended Solids (TSS). Previously developed filtration equations, which had been successfully applied to infiltration practices, were selected to model the pollutant removal efficiency of LIDs. The equations were adapted to integrate with the widely used EPA SWMM, through its Add-in Tools feature. Continuous modelling is applied to investigate the long-term performance of such practices, including clogging of the filter media. Monitoring data for various LID practices has been collected and are available through different institutions. This data is used to calibrate and verify the developed model, indicating that a close match between the predicted removal efficiency of different LIDs and monitoring results can be obtained. Simulation results are benchmarked against the results from other software that has some capability of calculating pollutant removal by LIDs, including WinSLAMM. The results of this study may be used as reference in the approval process of the proposed stormwater management facilities for new and retrofit developments.