The wonks call it “virtual water” – the water consumed elsewhere that is embodied in an imported product.
When I grow a tomato in my yard, it’s a bit hard to sort out, molecule by molecule, where the water comes from. Right now, about three quarters of the molecules come from mined groundwater, and one quarter are imported from the Colorado River Basin, through a tunnel beneath the continental divide.
When I buy a tomato in the market, the water is all consumed elsewhere (Lissa, who does our tomato buying, thinks they’re coming from California or Mexico.) As Michael Tobis suggests, the importation costs are drastically reduced in the process (substitute “New Mexico” for “Texas”, the idea is the same, current drought conditions notwithstanding):
Meanwhile, which is more expensive (more energy intensive) to ship to Texas: a tomato, or enough water to grow a tomato?