Guardian: The average Briton uses 150 liters of water a day; the average American gets through 570 liters (150 gallons) of the stuff. The world is getting thirstier and the global demand for fresh water is rising by 640 billion liters (169 billion gallons) a year. Population growth is one factor, not only the need for drinking water and sanitation but also the need to produce more food. Agriculture accounts for 70 percent of water use. Even the push for biofuels to reduce consumption of fossil fuels has...