Water accounting is an approach which can be used to establish baselines of water resource availability and use, and to track changes in water flows and storage in a region over time. A water account can be used to identify whether water is available for further allocation, and to identify the sustainability of interventions at the basin scale; it provides information needed to optimize allocation, and develop water efficient strategies. 

Water accounting is a vital component of planning procedures for water resource management, particularly under conditions of water scarcity and in the face of increasing risks and uncertainties. Strategies addressing water scarcity must be based on a thorough understanding of the water balance, including water supply and demand and its spatial and temporal dimensions.