Capacity utilization of National Water and Sewerage Corporation (NWSC) water supply system in Northern Uganda: a case study of Arua Municipality

Abstract

Capacity utilization refers to the relationships between actual output that ‘is’ produced with the installed equipment and the potential output ‘which’ could be produced with it if capacity is fully utilized. The capacity utilization of water supply system is dependent on factors that affect the water production, supply and demand. A study to establish the cause of low capacity utilization of a water supply system of Arua Municipality was done for a period of 10 months. Arua Municipality is found in Northwest part of Uganda. The water supply system of Arua Municipality was designed to operate at a practical capacity of 5400 cubic meters per day but operates at a capacity of 31%. In order to establish the cause of low capacity utilization, production efficiency of the abstraction and treatment subsystem, transmission and reservoir subsystem, and distribution subsystems were evaluated using produced water volumes in a period of ten consecutive months. Using flow from River Enyau for a period of 40 years, it was established that 58,500 cubic meter (municipality monthly demand) of water can be abstracted from it per month without causing adverse effect to the environment. Considering electricity power consumption by the abstracting plant, the effect of power interruptions was investigated. A questionnaire was administered to water users to determine household consumption, willingness to pay and affordability of water by Arua Municipality residents. The abstraction and treatment subsystem was found to have the lowest efficiency of 80% (standard deviation 500 cubic meter) of the three subsystems despite River Enyau having the capacity to supply the required quantity of water of 82000 cubic meters. Electric power interruptions were the major cause of low abstraction volumes and hence the major cause of low capacity utilization of the system. Water demand exceeded the production capacity of the plant by 43%. Even though the population’s willing to pay for water has been established to be four times higher than the current price levied by NWSC, 30% of the population cannot afford to pay for water at this price. Intermittent water supply, low quantity supply, low network coverage and high price levied by NWSC were the most significant problems experienced by the customers. It is recommended that 20 Photovoltaic Pumps of capacity 60 cubic meter per day and hydraulic load of 3000 cubic meter per day be installed at the site to supply the 43% demand deficit.