Installation packages for the program are available from the Hydrologic Engineering Center (HEC) website where the current version of the program is always available: https://www.hec.usace.army.mil/software/hec-hms/downloads.aspx.

Old versions of the program are archived and can be downloaded. However, old versions are not maintained, contain bugs and errors, and may not function correctly with current versions of the supported operating systems.

Microsoft Windows Operating System

There are two options for installation on Windows: an installation package or a portable archive.

Windows Installer

In order to run the installer you must have Administrator privileges on your computer. You only need the privileges during installation; once installation is complete the program can run successfully without Administrator privileges. If you do not have Administrator privileges, the installer will notify you and quit. Please contact your system administrator for assistance during installation.

After you have obtained the installer and Administrator privileges, use the following steps to install the program:

Run the HEC-HMS 4.4 Setup Package downloaded from the HEC website.
Depending on your security settings, you may receive a warning before the installer starts. The installer is signed with a digital signature so you can verify it was produced by HEC and has not been altered. If the digital signature is OK, press the Run button to proceed with starting the installer.
The installer will open in a new window and perform some preliminary configurations in preparation for installation. A welcome window will notify you that HEC-HMS 4.4 will be installed. Press the Next button to continue with the installation.
The next window will display the terms and conditions for using the program. This must be accepted during installation and later by every user who starts using the program on the computer where it is installed. Please read the terms and conditions for use carefully. If you agree, click the "I agree to the above Terms and Conditions for Use" radio button, and then press the Next button. If you do not agree, the installer will exit without installing the program.
The next window is used to select the location where the program will be installed on the local disk. It is recommended that the default location in the C:\Program Files folder be used. Press the Next button when you are satisfied with the installation location.
The next window allows you to choose if a shortcut to the program will be placed on the desktop. Program shortcuts will automatically be created in the Start menu under the All Programs | HEC folder, so having a desktop shortcut is optional.
The next and final window allows you to confirm that you are ready for installation. If you would like to change any of the previously configured settings, you may use the Back button. Press the Install button to install the program with all of the configuration information specified in the previous windows.

The installer will copy all necessary files and make additional configuration changes to the operating system. You do not need to restart the computer after the installation completes. At any time you can uninstall the program through the Control Panel. When future versions of the program become available, you may have each version separately installed on your computer.

Portable Version

The portable version is distributed as a zip archive. Unpack the archive to the desired location on your computer.

Linux Operating System

The distribution package is a compressed archive.

Manual Install

This installation guide was tested in the following environment:

HEC-HMS v.4.4
OS: Ubuntu 18.04 LTS
Mpich 3.3~a2-4
GDAL 2.4.2

Install Necessary Dependency Packages

Install the necessary libraries for TauDEM (C++, MPI, and GDAL) using the following commands:

sudo apt-get install build-essential

sudo apt-get install mpich

Add UbuntuGIS PPA to install GDAL Libraries:

sudo add-apt-repository ppa:ubuntugis/ppa

sudo apt-get update

Install the GDAL Libraries:

sudo apt-get install gdal-bin

sudo apt-get install libgdal-java

Install HEC-HMS

Download the latest HEC-HMS version.

Unpack the archive:

tar -xzf /tmp/HEC-HMS-<version>.tar.gz -C /tmp

Install (this guide uses /opt but feel free to choose a different directory):

sudo mv /tmp/HEC-HMS-<version> /opt/HEC-HMS-<version>

HEC-HMS is now installed. When future versions of the program become available, you may have each version separately installed on your computer. You will need to carefully organize the installation locations so that each version can be kept separate.