Water Infrastructure Division
Center for Environmental Solutions and Emergency Response
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH 45268


This User Manual is an updated version of the EPANET 2 Users Manual (EPA/600/R-00/057) written by Lewis Rossman in 2000. The EPANET 2 software was developed by the United States Environmental Protection Agency (EPA).

EPANET Version 2.2 includes contributions from EPA and individuals outside the United States Government. It has been subjected to review by the Office of Research and Development and approved for publication. Approval does not signify that the contents reflect the views of the Agency, nor does mention of trade names or commercial products constitute endorsement or recommendation for use.

Execution of any EPANET installation program, and modification to system configuration files must be made at the user’s own risk. Neither the U.S. EPA nor the program author(s) can assume responsibility for program modification, content, output, interpretation, or usage.

EPANET installation programs have been extensively tested and verified. However, as for all complex software, these programs may not be completely free of errors and may not be applicable for all cases. In no event will the U.S. EPA be liable for direct, indirect, special, incidental, or consequential damages arising out of the use of the programs and/or associated documentation.

EPANET 2.2 User Manual Overview

This manual describes how to run version 2.2 of the EPANET water distribution system simulation model. Notable improvements made by this version include:

  • The ability to use pressure-dependent demands in hydraulic analyses.
  • An option to allow full tanks to overflow.
  • Options that insure a more accurate hydraulic analysis is made.
  • More robust handling of low and zero flow hydraulic conditions.
  • Faster solution times for single period hydraulic analyses.
  • Improved mass balance results for water quality analyses.
  • An enhanced API function library for customizing EPANET (see http://wateranalytics.org/EPANET/).

The following topics are covered in this Manual:

Introduction of this manual describes what EPANET is and its capabilities.

Quick Start Tutorial describes how to install EPANET and offers up a quick tutorial on its use. Readers unfamiliar with the basics of modeling distribution systems might wish to review Chapter 3 first before working through the tutorial.

The Network Model provides background material on how EPANET models a water distribution system. It discusses the behavior of the physical components that comprise a distribution system as well as how additional modeling information, such as time variations and operational control, are handled. It also provides an overview of how the numerical simulation of system hydraulics and water quality performance is carried out.

EPANET’s Workspace shows how the EPANET workspace is organized. It describes the functions of the various menu options and toolbar buttons, and how the three main windows – the Network Map, the Browser, and the Property Editor—are used.

Working with Projects discusses the project files that store all of the information contained in an EPANET model of a distribution system. It shows how to create, open, and save these files as well as how to set default project options. It also discusses how to register calibration data that are used to compare simulation results against actual measurements.

Working with Objects describes how one goes about building a network model of a distribution system with EPANET. It shows how to create the various physical objects (pipes, pumps, valves, junctions, tanks, etc.) that make up a system, how to edit the properties of these objects, and how to describe the way that system demands and operation change over time.

Working with the Map explains how to use the network map that provides a graphical view of the system being modeled. It shows how to view different design and computed parameters in color-coded fashion on the map, how to re-scale, zoom, and pan the map, how to locate objects on the map, and what options are available to customize the appearance of the map.

Analyzing a Network shows how to run a hydraulic/water quality analysis of a network model. It describes the various options that control how the analysis is made and offers some troubleshooting tips to use when examining simulation results.

Viewing Results discusses the various ways in which the results of an analysis can be viewed. These include different views of the network map, various kinds of graphs and tables, and several different types of special reports.

Printing and Copying explains how to print and copy the views discussed in Viewing Results.

Importing and Exporting describes how EPANET can import and export project scenarios. A scenario is a subset of the data that characterizes the current conditions under which a pipe network is being analyzed (e.g., consumer demands, operating rules, water quality reaction coefficients, etc.). It also discusses how to save a project’s entire database to a readable text file and how to export the network map to a variety of formats.

Analysis Algorithms provides details of the procedures and formulas used by EPANET in its hydraulic and water quality analysis algorithms.

Frequently Asked Questions answers questions about how EPANET can be used to model special kinds of situations, such as modeling pneumatic tanks, finding the maximum flow available at a specific pressure, and modeling the growth of disinfection by-products. The manual also contains several appendixes.

Units of Measurement provides a table of units of expression for all design and computed parameters.
Error Messages is a list of error message codes and their meanings that the program can generate.
Command Line EPANET describes how EPANET can be run from a command line prompt within a DOS window, and discusses the format of the files that are used with this mode of operation.