The EPANET Programmer’s Toolkit is a collection of functions that helps simplify computer programming of water distribution network analyses. The functions can be used to read in a pipe network description file, modify selected component properties, run multiple hydraulic and water quality analyses, retrieve selected output results, and write formatted output reports. The toolkit is especially useful for developing applications, such as optimization models, that require running many network analyses with modified input parameters. It can also simplify adding analysis capabilities to integrated network modeling environments based on CAD, GIS, and database packages. (Source: http://ascelibrary.org/doi/abs/10.1061/40430%281999%2939)