Water distribution system (WDS) aims to distribute water from reservoirs or aqueducts to the end-users. This system is part of the water supply network that carries potable water from a central treatment plant or wells to water consumers in order to deliver water sufficiently to meet residential, commercial, industrial, and firefighting requirements. Modern systems aim to solve water distribution systems management problems, such as the lowest cost, and most efficient design by using linear/nonlinear optimization schemes, which are limited by the system size, the number of constraints, and the number of loading conditions. After a literature review for the articles that dealt with this topic, designing two parts of the water distribution system is discussed as a case study in Erbil. Pumps and storage tanks, while optimizing the water distribution system by minimizing the project cost through minimizing the volume of the elevated tank according to the pump working hours.