 The world's total water footprint related to crop production in the period 1996 to 2005 was 7,404 billion cubic meters per year, 78 percent green, 12 percent blue, 10 percent gray. Wheat and rice have the largest blue water footprints, together accounting for 45 percent of the global blue water footprint. A relatively large total blue water footprint as a result of crop production is observed in the Indus River Basin, 117 GM3 year minus one, and the Ganges River Basin, 100 and 8 GM3 year minus one. This article was authored by M. M. McConan and A. Y. Hoekstra.