Although important topic - many regions already suffer from acute water shortage, at least for half of the year - global aggregate numbers don't mean so much, as large-scale inter-regional water transport isn't practical. There are a few exceptions - China has it's N-S water transfer project, there's potential for a canal from Congo to Chad. Transfer by evapotranspiration is big, but not really planned. There's also water (and energy) embedded in food, could be reduced if people care. Anyway what's new (not this article)?