Your Water Footprint

Stephen Leahy’s Your Water Footprint (Firefly Books, Ltd., 2014) presents some rather staggering statistics about the amount of water it takes to make everyday products enjoyed by consumers of wealthy societies.  4,068 gallons (15,400 liters) of water to produce 2 pounds (1 kilogram) of beef;  2,747 gallons (10,400 liters) of water to produce 2 pounds of lamb; 1,582 gallons (5,990 liters) of water to produce 2 pounds of pork; 1,136 gallons (4,300 liters) of water to produce 2 pounds of chicken.  A single egg, Leahy suggests, takes 52 gallons to produce.  “depending upon where the food is produced, the water footprint may be big or small.” Quoting Arjen Hoekstra, “86% of humanity’s water footprint is not within people’s homes, but in making food, natural fibers, oils and energy.”  The single tomato that Leahy suggests takes 9.3 gallons of water to produce certainly consumes a lot less water in my own garden.

According to Leahy (the attribution of his data is a little obscure) 3,095 cubic miles (12,900 cubic kilometers) of fresh water hangs in the atmosphere (due to evaporation and transpiration during photosynthesis).  30 trillion gallons (113 trillion liters) of water fall to earth in precipitation each day.  The world’s three largest aquifers hold 15,600 cubic miles (64,900 cubic kilometers) (Australia’s Great Artesian Basin), 9,600 cubic miles (40,000 cubic kilometers) (South America’s Guarani Aquifer), and 900 cubic miles (3,608 cubic kilometers) (North America’s Ogallala Aquifer).  That’s a lot of tomatoes.

While Leahy’s implied guilt trip for rich-country consumers is worth considering, it fails to consider the water justice questions.  Where is the major water consumption?  In the factory or field?  In the home?  Although water supply is essentially geostationary—it is hard to export the resource itself by means other than global, atmospheric processes—the natural resource converted to products conveyed long distances (across oceans)  makes the total global water supply relevant.  But it may be the modern structure of international production, trade, transportation, corporate structure and finance which constitutes the major component of the justice problem.  Increase in global population, rise in energy demand and production, climate change likely also play a part.  So I won’t feel too guilty when I eat my home-grown tomato.