Actual or Virtual Water?

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?


  1. How much more water does it take to grow a tomato than is in a tomato, including evaporation?

  2. its unclear which activity, growing or shipping a tomato is more “energy intensive”, because of the start up costs. The energy it takes to make the truck, wheels and mostly to power it’s motion across large distances with petroleum is not much compared to the energy to build a tunnel to transfer water from the San Juan basin to ABQ and build the water delivery infrastructure that delivered the water to your growing tomato. However, similar water infrastructure was likely built at the other long distance tomato growing location too. Maybe the best way to think about it is to buy a tomato grown in the Middle Rio Grande valley where the ditches were (at first) hand excavated and water was diverted with some infrastructure but is otherwise based on the energy of river runoff and gravity delivery. Or grow tomatoes on the rain runoff you’ve collected from your roof and Bonn appetite!

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