Making waves – Are water scarcity footprints of irrigated agricultural commodities suitable to inform consumer decisions?

Fresh water is a limited global resource. Water scarcity footprints (WSF) have been developed to guide the choices of consumers and supply chains to reduce unsustainable fresh water consumption. The Available WAter REmaining (AWARE) method, which is the only method to have gained global consensus, assigns WSF for a commodity or product relative to the scarcity of water in the catchment in which production occurs. This results in products from water-stressed catchments that have a higher WSF than a similar product, using a comparable amount of water, in water-abundant catchments. The characterisation of water stress is developed using the WaterGap global hydrological model. Here, we use the Murray Darling Basin (MDB) to highlight how WaterGap does not reflect the impacts that legislation and infrastructure have on the relative volumes of water available for agriculture and the relationship between when (and where) water enters a catchment and when it is used for agriculture. Given that these issues are not unique to the MDB, it is likely that the AWARE WSF misrepresents the water stress experienced in other regulated catchments around the world. We conclude that for a WSF to be a useful indicator to guide consumer and supply chain decisions in supporting sustainable water consumption, it needs to reflect responsible management, such as setting aside water for the environment, placing caps on extractions, and the ability to hold water or transport water well beyond when and where it enters a catchment. Ultimately, WSF should also include a mechanism to assess burden shifting, especially if consumer or supply chain decisions were to mean that production moved to another catchment.