Development of scenarios for evaluating conversion from intermittent to continuous water supply strategies’ sustainability implications

Planning the conversion from intermittent to continuous water supply (CWS) is rife with uncertainties. Although scenarios can be used to incorporate uncertainties in planning processes, their development and application to intermittent water supply systems are uncommon. Using drivers of water demand in water supply systems, this study developed four scenarios (business-as-usual, consumption demand management, non-revenue water (NRW) management, and holistic) for water supply systems. The scenarios were applied to the Lusaka water supply network in Zambia. The results showed that the NRW management scenario, which used the projections in the water supply investment master plan for Lusaka, is unsustainable because of insufficient water as the 15% NRW target is practically unattainable by 2035. The holistic scenario is the most sustainable, but the commitment to ensure its occurrence in Zambia is currently lacking. Possibly, donors' directives can instil the commitment needed to attain the holistic scenario and the conversion to CWS.