This manual aims at walking the reader through the design of a water supply network in a Development context by explaining in a simple manner how to build and analyze a computer model of a water network with Epanet. Epanet is a free and widely used software from the U.S Environmental Protection Agency that models the hydraulic and water quality behavior of water distribution piping systems Arnalich Water and Habitat is an organization that helps improve the impact of humanitarian actors through training and consultancy in the fields of Water Supply and Environmental Engineering.