nonlinearities in the nature of water problems themselves eg the risk of irreversibility as well as uncertainty about the linkages between water risks and the economic values placed by producers and consumers on potential changes in water security will make very complex any systematic effort to compare the costs and benefits of proposed targets the economic value of water security improvement or impairment can be difficult to capture especially when that value cannot be derived from direct use of water resources likewise the costs of policy inaction should also regularly be assessed