Rainfall Derived Inflow (RDI) as a part of Rainfall Derived Inflow and Infiltration (RDII) has been known to cause various issues around the globe. Common issues resulting from excessive RDI range in magnitudes, from residential basement flooding to urban city flooding. Significant effort and time have been spent to attenuate RDI and reduce the risk of flooding which causes extensive environmental and financial losses. While continuing the effort in reducing RDI/RDII, it is difficult to characterize its volume accurately. In this research, using a local community as a case study site, a novel method is presented to characterize RDI with high accuracy. A general guidance is developed for engineers to determine the data size needed to correctly estimate RDI in the future. Furthermore, a Storm Water Management Model is created to examine the efficiency of Low Impact Development LID devices at lot-level, including its performance under climate change.