it is driven by the intersection of hazards exposure and vulnerability water shortage arises from conditions of scarcity which can be defined as an imbalance between the supply and demand of freshwater as a result of a high level of demand compared to available supply under prevailing institutional arrangements including price and infrastructural conditions winpenny economic scarcity exists when there has been underinvestment in water infrastructure to supply sufficient amounts of water absolute scarcity exists when there is no affordable source of additional water or where the costs of additional water supplies exceed the benefits of their provision