ABSTRACT: This document describes the program SWMM (Storm Water Management Model) developed U.S.EPA Agency (Agency for Environmental Protection of the United States). SWMM program is a dynamic rainfall-runoff simulation model that allows you to simulate rainfall-runoff processes from an urbanized area and is used around the world. The benefits of this program are: free download, simple user interface, a wide range of inputs and outputs. Small drawbacks include: failure to insert a dwg. format. Incompatibility with GIS. Runoff process is based on a sub-catchment where rain falls and where there is surface runoff and pollution. SWMM monitors the quantity and quality of wastewater within each area. It also monitors the flow, depth and quality of water in different parts of the pipes and drains during the simulation, consisting of several time steps.