Reply to Ridoutt and Huang: From water footprint assessment to policy

According to Ridoutt and Huang (1), “environmental relevance must be taken into consideration if water footprints are to inform wise decision making and policy development.” Indeed, reduction targets regarding water footprints (WFs) within catchments should be formulated on the basis of relative water scarcity per catchment, because local environmental impact of water use is generally larger when scarcity is higher. In many river basins, the blue WF exceeds blue freshwater availability, causing substantial environmental impact (2). However, local environmental impact is only one of a range of factors to be considered when prioritizing options for WF reduction (3). Other relevant factors are global sustainability, social equity, and economic efficiency.