Water and food

Some of the startling statistics about water in When the Rivers Run Dry, written by Fred Pearce:

• 25 gallons to produce a portion of rice


• 40 gallons for the bread in a sandwich


• 130 gallons for a two-egg omelet or mixed salad


• 265 gallons for a glass of milk


• 400 gallons for ice cream


• 530 gallons for a pork chop


• 800 gallons for a hamburger


• 320 gallons for a small steak


• 50 cups for a teaspoon of sugar


• 37 gallons for a cup of coffee


• 66 gallons for a glass of wine/beer


• 530 gallons for a brandy


• 1200 gallons (assuming 50 gallons/bathtub) to grow 9 ounces of cotton

Pearce talks about the relative water consumption of various human activities:

• drinking: 265 gallons (1 ton)/year


• home use: 50-100 tons/year


• food and clothing: 1500-2000 tons/year

That makes clear that the bottleneck is clearly food and clothing, and that becoming vegetarian might actually be the best way to conserve water.

While I was walking home last night, I came to the minor realization that if we treat the human-earth relationship as a complex system, then some resource will always be the bottleneck. Pearce's book implies that it as water; the more obvious candidate (from a public perspective) has been energy (oil).