The program performs extended period simulation of hydraulic and water quality behavior within drinking water distribution systems. It tracks the flow of water in each pipe, the pressure at each pipe junction, the height of water in each storage tank, and the concentration of a substance throughout a distribution system during a multi-time period simulation. In addition to substance concentrations, water age and source tracing can also be performed. The water quality module of EPANET is equipped to model such phenomena as reactions within the bulk flow, reactions at the pipe wall, and mass transport between the bulk flow and the pipe wall. The documentation describes how to use the EPANET program on a personal computer under both DOS and Microsoft Windows. Under Windows the user is able to edit EPANET input files, run a simulation, display the results on a color coded map of the distribution system and generate additonal tabular and graphical views of these results.