The water-using networks with internal water mains have the advantages of easy operation and control compared to the conventional ones.The concentration potential is a new concept proposed recently.In this paper

a design method for water-using networks with internal water mains is presented.The new method designs an initial water-using network by using the concentration potential method first.The structure and water quantity of the internal water mains are determined based on the initial network obtained.Each demand is satisfied by an internal water main according to the ascending order of the concentration potentials of the demands.The water quantities of the internal water mains are determined by satisfying the corresponding water demand.This method can design a water-using network with two internal water mains by simple calculation.The results obtained by using the method proposed for a few case studies in the literature are close to those obtained by the mathematical programming method.