Pressure management as a leakage reduction and water demand management tool: The case of the City of Mutare, Zimbabwe

Water is now considered a scarce but essential resource, which should be managed in an integrated manner. The traditional approaches of resource development are now considered as unsustainable. Water demand management (WDM), the new approach, aims at influencing demand, thus improving distribution efficiency. Leakage control and pressure management are some of the WDM strategies.The study was carried out in Mutare and investigated the potential for leakage control through pressure management. The city experiences high water losses due to an aged system of reticulation, faulty metering of 25% and high system pressures. Unaccounted for water (UFW) for the city during the study period averaged 57%. UFW for the two specific study areas in Chikanga averaged 47% and 32%. One of the areas was investigated for leakage reduction through pressure management. The normal operating pressure in the system was 75–80 m. Epanet was used for modelling pressure distribution. Results from logged minimum night flows (MNF) show that at 77 m UFW due to leakage was 25%. A pressure reduction from 77 m to 50 m resulted in 25% reduction in MNF. Further reduction of pressure below 50 m resulted in deterioration of service. No flow was received at the highest point when the pressure was set at 30 m. At this pressure, results from Epanet gave −0.84 m pressure at the highest point. The hydraulic model predicted 50 m as minimum pressure for an acceptable minimum pressure in the system. It was concluded that operating the system at 50 m in the area under pressure management reduced the MNF by 25% without affecting the service. There is great potential for leakage control through pressure management. It is recommended that leakage control through pressure management be investigated in other parts of the city using Epanet as a tool. Replacement of very old pipes should be considered together with other strategies.