The Water Footprint for different diets

The results of a recent paper by Vanham et al. (2013) are no surprise: "Vegetarian diet reduces water footprint & external water dependency"

However, it can be expected that the consumption of animal products will increase. Certainly not only in the EU. Increasing consumption of animal products and the effects thereof will be of particular relevance in fast growing countries such as China (see also Liu and Savenije (2008)) and India.

From the abstract of the paper by Vanham et al. (2013):
In this paper, the EU28 (EU27 and Croatia) water footprint of consumption (WFcons) for different diets is analysed: the current diet (REF, period 1996-2005), a healthy diet (DGE), a vegetarian (VEG) and combined (COM) diet. By far the largest fraction of the total WFcons (4815 lcd) relates to the consumption of edible agricultural goods (84%). The average EU28 diet is characterised by a too high energy intake and a too high ratio of animal to vegetal protein intake. For a healthy diet, the intake of some product groups should be reduced (sugar, crop oils, meat and animal fats) and of other product groups increased (vegetables and fruit). Especially the consumption of animal products accounts for high WF amounts. The three alternative diets result in a substantial reduction (−974 lcd or −23% for DGE, −1292 lcd or −30% for COM, −1611 lcd or −38% for VEG) of the WFcons for agricultural products with respect to the existing situation (REF, 4265 lcd). The reduction in meat intake contributes most to the WF reduction. Each of the specific WF components (green, blue and grey) shows a reduction similar to the observed reduction in the total WFcons. Regarding the total WFcons (green, blue and grey WFcons) as well as the WFcons without the grey WF component (green + blue WFcons) for agricultural products, the EU28 shifts from net virtual water (VW) importer for the REF and DGE diets to net exporter for the COM and VEG diets.

Regarding food consumption vs effect on water resources there is an interesting study by Liu and Savenije (2008), "Food consumption patterns and their effect on water requirement in China". One finding was that per capita water requirement for food (CWRF) has increased from 255m3 cap−1y−1 in 1961 to 860m3 cap−1 y−1 in 2003, largely due to an increase in the consumption of animal products in recent decades. Interesting is the analysis of three modernization scenarios. Liu and Savenije (2008) find that an additional amount of water ranging between 407 and 515 km3 y−1 will be required in 2030 compared to the total water requirement for food (TWRF) in 2003.


References:
Liu, J. and Savenije, H.H.G. (2008) Food consumption patterns and their effect on water requirement in China, Hydrology and Earth System Sciences 12(3): 887-898.
available at:
http://www.waterfootprint.org/Reports/Liu-Savenije-2008-China.pdf

Vanham, D., Mekonnen, M.M. and Hoekstra, A.Y. (2013) The water footprint of the EU for different diets, Ecological Indicators, 32: 1-8.
available at:
http://www.waterfootprint.org/Reports/Vanham-et-al-2013.pdf