Potentials for Improvement of Energy Efficiency for New Design of Water Distribution Systems

Energy expenditure from pumps in water supply systems can account for up to 50 % of the running costs of a water distribution system. The purpose of this paper, based on the second author's MSc dissertation is to present the results of cost-benefit analyses with regards to pumping costs for a water distribution system if it were to be designed form scratch. A case study of a real life system is used to demonstrate the methodology proposed. Current practice involves pumping to high water tower elevations and in many cases reducing system pressure in areas of the network by use of pressure reducing valves (PRVs). This causes unnecessarily high pumping costs and may also lead to leakage and bursts within the system. The proposed alternative considers pumping to lower elevations with subsequent boosting to regions with low pressures in order to reduce the risks of leakage and pipe failure, as well as pumping costs within the system. It was found that the use of boosting pump in a system with low tower elevation proved to be up to 19% more cost-effective than using PRVs in systems with high water tower elevations.