used to model full flow conditions under simplified conditions (turbulent flow, temperature around 60 degrees Fahrenheit, and viscosity similar to water) https://www.epa.gov/water-research/epanet Darcy-Weisbach formula: used to model pressurized flow under a broader range of hydraulic conditions Chezy-Manning formula: used to model pressurized flow by using Chezy's roughness coefficients for Manning's equation Since the pipe segment headloss equation is used within the network solver, the formula above is selected for the entire model. Head-flow Curves of Pumps Within EPANET, pumps are modeled using a head-flow curve, which defines the relationship between hydraulic head imparted to the system by the pump and flow conveyed by the pump. The model calculates the flow conveyed by the pump element for a given system head condition based on this curve. EPANET can also model a pump as a constant power input, effectively adding a given amount of energy to the system downstream of the pump element. Network solver The network hydraulics solver employed by EPANET uses the "Gradient Method" first proposed by Todini and Pilati, which is a variant of Newton–Raphson method. Water-quality simulation EPANET includes the capability to model water age and predict flow of non-reactive and, under simplified conditions, reactive materials. This capability is frequently used to predict chlorine residuals within water distribution systems. While the internal water quality simulation capabilities only evaluates decay or growth of a single constituent, an extension is available (EPANET-MSX), which allows modeling of interactions between constituents. EPANET Toolkit EPANET's computational engine is available for download as a separate dynamic link library for incorporation into other applications. The source code for EPANET 2 is available on the EPA's EPANET website. In 2012 the EPANET toolkit, written in C, was rewritten in Java in a more object-oriented style. The code in Java is available on GitHub: https://github.com/Baseform/Baseform-Epanet-Java-Library. Compatibility EPANET uses a binary file format, but also includes the capability for importing and exporting data in dxf, metafile, and ASCII file formats. EPANET's ASCII file format is called an input file within EPANET, and uses a file extension ".inp". The input file can include data describing network topology, water consumption, and control rules, and is supported by many free and commercial modeling packages. While EPANET is used as the computational engine for most water distribution system models, most models are developed and maintained in hydraulic modeling packages based on EPANET's computational engine. Some of the major hydraulic modeling packages are: