The overarching purpose of the risk characterisation process is to produce the best possible estimate of the broader economic, social and environmental implications of the risk. This is one of the most challenging and controversial tasks in the risk management process (Klinke and Renn, 2012). Indeed water security touches upon the issue of allocating water risks between residential, agricultural, industrial and environmental uses, a significant political economy question, as each will define essential or adequate in different ways.s For instance, much of the current policy debate in Australia’s Murray-Darling Basin is about reallocating water from irrigation to sustaining the ecosystems. The reallocation of water among users can be seen, in effect, as a reallocation of water risks. In this example, the shift in allocation increases the risk of shortage to irrigators in an effort to decrease the risk to the resilience of freshwater systems.