Equity – performance trade-off in water rationing regimes with domestic storage

Water rationing contributes to inequalities in the water supply. Household storage tanks complicate the performance and the hydraulic modelling of these systems. Rationing is often not based on insights into system performance and fails to achieve equity and the operators struggle to explain the rationing tactics to the stakeholders. Understanding the behaviour of water networks rationed regularly is essential to resolve the supply inequalities. We present a contextual analytical framework for understanding and managing water rationing based on the duration of supply (cycle time), rationing fraction (duration of non-supply) and domestic storage to analyse the equity and performance in the water network. The framework was tested using a model of a distribution network in Kakkapalliya, Sri Lanka, under different rationing schemes. The results show that large household tanks create inequities, which can be reduced through a trade-off by increasing the cycle-time of the rationing with a minor reduction in performance. Very small or non-existent domestic storage also negatively impacts the performance and equity of stressed water networks. Resolution of supply inequalities can be achieved through the trade-off between equity and performance is possible through the operation of the water network and by the regulation of domestic storage in water rationing regimes. HIGHLIGHTS Combine the complexity of domestic water storages with intermittent water supply to identify the impacts on supply performance and equity.; Larger domestic storages create inequity at shorter rationing cycle times.; Longer cycle times can mitigate inequity at a small cost on supply performance.; In stressed networks, small (∼daily demand volume) domestic storage can improve performance and equity as opposed to no storage.;