WFA comprises (i) setting goals and scope; (ii) quantification and location of the water footprint of a process, product, producer or consumer, or quantification in space and time of the water footprint in a specified geographic area; (iii) assessment of the environmental, social and economic sustainability of this water footprint; and (iv) formulation of a response strategy. As Hastings and Pegram (2012) and Vanham and Bidoglio(2013) point out, determining and assessing water footprints, in particular for river basins, is challenging in terms of data requirements, and the method still needs to be refined further, particularly with respect to grey-water footprint accounting (recent advances are shown by Franke et al. (2013)), and in terms of social and economic sustainability assessment.