The rapid increase in world population has increased the demand of food and biofuels leading to stress on water resources and increase in competition between different sectors around the globe. Under the combined impacts of climate change, population growth, urbanization and economic development, the pressure on the water resources is continually increasing. Therefore, an appropriate approach is required for effective water accounting. Water footprint concept has been introduced to indicate the water use and impact of production systems on water resources. In this study, two different approaches for the estimation of water footprint of crops have been reviewed, i.e. the Water Footprint Network (WFN) approach and Life Cycle Assessment (LCA). These approaches are used in many countries and numerical models have been developed to facilitate the calculations. By clarifying the concerns about water accounting, we identify that the main differing perspective between the WFN and LCA approaches is that LCA aims to account for the environmental impacts related to water resources, while WFN aims to account for water productivity of global fresh water as a limited resource. We conclude that the WFN approach could benefit from considering the impact assessment methodologies evolving within the LCA community and joint efforts could lead to some consensual metrics to better assess the sustainability of freshwater use.

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