A new and rational approach to modelling and designing potable water and electricity supply systems in African cities

The problems of supplying African cities with potable water and electricity are characterised by uneven capacities of the networks, inefficiencies of supply, low subscription rates and low rates of return. This paper proposes ways of improving access rates of city dwellers to potable water and electricity without reducing the technical and commercial efficiencies of network managers. The main innovation consists in associating urban households to technical decisions aimed at expanding the network programming, by collecting pertinent variables such as consumption levels and contributive capacities of households, thus highlighting the need to draw up flexible and appropriate standards. These are formulated in terms of consumption and failure rates, and in terms of the thresholds used to evaluate risk and availability. The graphical method of risk evaluation developed here may be a useful tool for decision making on matters related to network extension. The model developed was tested in three Cameroonian towns. A comparison of this method with the classical approach shows that the method improves availability by as much as 40% in the three towns studied, while also improving significantly the technical and commercial efficiencies.