The process of converting the Philadelphia Water Department’s (PWD) existing Combined Sewer System (CSS) model from SWMM4 to SWMM5 was initiated in late 2009. Historically, PWD has used SAS for all its post-processing. These post-processing tools were converted from SAS to the freely available statistical program R. Here we describe those revamped post-processing tools as well as some new tools for reformatting SWMM5 outputs, hydrograph visualization, and calculating statistics such as overflows and treated volumes at regulating structures. Unlike SWMM4, SWMM5 text output files are not formatted so that flow, level and water quality information can be easily, sequentially and efficiently read in or post-processed using programs like SAS and Excel. Timeseries information for links and nodes are stacked, and the Date/Time information is redundant. A reformatting program was developed in Python, which reduces the information to just pipe or subcatchment timeseries (i.e., flow, velocity, depth, etc.) and places the information into adjacent columns. Reformatted SWMM5 results were visually compared to SWMM4 results using a program developed in R. One converted tool assists in model calibration, allowing users to visually and statistically compare simulated and observed flows and depths; the program summarizes and performs regressions of observed flow volumes and peaks to simulated volumes and peaks. Another R program was written for post-processing the SWMM5 results for the CSS model (capture program). This program processes simulation results and reports both volumes overflowed to receiving waters and volumes treated at the WWTP during wet weather periods.