Pressure Management as a Tool for Reduction and Control of Real Water Losses for Kasungu Water Supply Scheme in Malawi

Abstract

Research has shown that effective management of water resources for urban water utilities worldwide still remains a challenge. Pressure management is one of the tools that is known to control water leakages in piped water supply systems. A study was carried out on Kasungu Water Supply Scheme in Malawi from February to April 2009 to investigate the potential of pressure management as a tool for the reduction and control of real water losses. The study also assessed the viability of pressure management and its impacts on service quality. Levels of unaccounted-for water (UFW) for Kasungu Water Supply Scheme in the period July 2007 to June 2008 were reported to be 27% on average with a maximum of 37% in May 2008. An area called Kasungu ADD was selected for pressure and flow measurements to determine the variation of leakage under different pressures and the impact of pressure management on service quality. The study showed that 66% of the total non-revenue water in the scheme is lost through leakage and that leakage in the distribution system is reduced by 38% when pressure is reduced by 46%. At 38% inlet pressure reduction minimum night flows (MNF) were reduced by 34%. However the time required to fill a 20 litre bucket during the peak period, a measure of service quality, increased by 9% at critical points of the system Pressure management was found to have a payback period of 20 months compared to pipe replacement which had a payback period of 205 months. It was concluded that pressure management is a viable tool for controlling water losses in the scheme. It is recommended that the supply area should be pressure zoned and use of appropriate pressure controllers be implemented in the distribution system to improve management.