Quantifying the economy of water supply looped networks

The economic advantages of a looped network have not been explicitly considered in the objective function of optimization models found in the literature. This paper introduces a new formulation and methodology in an attempt to give a practical solution to this problem. The new formulation consists of a nonlinear optimization model that is solved by classical differential calculus and the Newton-Raphson technique. An example shows how the looped network can be less costly than a branched one. Previous research usually optimized the network for a given design demand, but the value that should be specified as the desired network reliability has not been reported so far. This work shows how to obtain not only an adequate value for the reliability of a looped network but also the appropriate design demand, based on a thorough cost analysis. A detailed example illustrates the performance of the methodology.