Reliability Analysis of Water Distribution Network: A Case Study of Bole and Yeka Sub-city of Addis Ababa, Ethiopia

Water is an essential requirement for the survival of life. Hence, it should be available to all consumers at their tap level with minimum possible cost. Water utilities should have reliable water supply systems (WSS) to fulfill the consumer’s demands. Keeping this in mind, this study focuses on assessing mechanical, hydraulic, and water quality reliability in the urban water distribution network (WDN) for normal and abnormal working conditions. The methodology is explained with the help of an illustrative example of Bole and Yeka sub-city urban water distribution network of Addis Ababa, Ethiopia, These WDNs are vulnerable to mechanical, hydraulic, and quality failures due to various reasons such as aging and corrosion, etc. The WDN is modeled using ArcGIS and then simulated using WaterGEMS software. Based on the simulation, hydraulic and water quality reliability were assessed. It has been observed that the hydraulic system reliability is 0.833 (rated as good) and 0.91 (very good) in terms of water quality reliability under normal conditions and 0.475 (poor) under abnormal conditions. Further, it is crucial to improve the system’s reliability for which it has been advocated to install pressure-reducing valves (PRV), additional booster pumps, booster disinfectant stations, and replacing the old pipelines with new/ additional (parallel) pipelines.