Considering the variations that are available from different vendors, EPA's SWMM 5 is the most widely used model for urban drainage as well as sanitary sewer systems. Compared to other commonly used hydrologic (e.g. HEC-HMS, HSPF, etc.) and hydraulic (e.g. HEC-RAS) models SWMM is unique because of its ability to simulate hydrology (i.e. the rainfall-runoff processes that generate flow) and hydraulics (i.e. open channel flow with backwater, flow through closed conduits, pumps and hydraulic structures, etc.) within the same model. The model can be used for a single event or a long-term simulation. Streams Tech provides SWMM resources for interested users.

Any experienced modeler would agree with the fact that a user would spend the most of his/her modeling time on preparing input data. By integrating SWMM with ArcMap, GeoSWMM helps users to significantly reduce the time it takes to prepare model input, increase the accuracy of input data, store and manage data in a database environment and visualize and inspect model objects on a map. It allows users to run simulation and view output without ever exiting the GIS environment.