From Wikipedia, the water footprint is an indicator of water use that includes both direct and indirect water use of a consumer or producer. The water footprint of an individual, community or business is defined as the total volume of freshwater that is used to produce the goods and services consumed by the individual or community or produced by the business.
1 kilogram of beef requires 16 thousand litres of water.
1 cup of coffee requires 140 litres of water.
China's water footprint is about 700 cubic meters per capita per year. Only about 7% of the Chinese water footprint falls outside China.
Japan, at 1150 cubic meters per capita per year, has about 65% of its total water footprint outside its own borders.
The water footprint of the US is 2500 cubic meter per year per capita.
Again from wikipedia
Water use is measured in water volume consumed (evaporated) and/or polluted per unit of time. A water footprint can be calculated for any well-defined group of consumers (e.g. an individual, family, village, city, province, state or nation) or producers (e.g. a public organization, private enterprise or economic sector). The water footprint is a geographically explicit indicator, not only showing volumes of water use and pollution, but also the locations. However, the water footprint does not provide information on how the embedded water is contributing to water stress or environmental impacts.
Professor Arjen Y. Hoekstra, creator of the water footprint concept and scientific director of the Water Footprint Network, explains why any of this matters. "Water problems are often closely tied to the structure of the global economy. Many countries have significantly externalised their water footprint, importing water-intensive goods from elsewhere. This puts pressure on the water resources in the exporting regions, where too often mechanisms for wise water governance and conservation are lacking. Not only governments, but also consumers, businesses and civil society communities can play a role in achieving a better management of water resources."
In the past 50 years, the world's water use has tripled. More than a third of the western United States sits atop groundwater that is being consumed faster than it's replenished. Half of the world's wetlands are gone, killed off in part by irrigation and dams, which have destroyed habitats along 60 percent of the planet's largest river systems. Since 1970, the population of freshwater species has been halved; one-fifth of all freshwater fish vanished in the past century—an extinction rate nearly 50 times that of mammals. And consuming more water has concentrated pesticides and fertilizers in what's left over: It's unsafe to swim or fish in nearly 40 percent of US rivers and streams, and polluted water sickens nearly 3.5 million Americans a year.
Farmers often get blamed for water use issues, like in California where 80 percent of the state's water goes to agricultural purposes. According to the Pacific Institute, better conservation on farms in the semiarid Central Valley could save 1.1 trillion gallons of water a year. That's 1.1 trillion gallons would just about supply the combined non-agricultural water needs of Nevada, Arizona, and Colorado combined.
Farmers are not always to blame, however. Many urbanites don't take water footprint into account when they make their daily decisions. It goes beyond just multiple toilet flushes a day and letting the faucet run while shaving or brushing your teeth. Another thing to take into account is the amount of water needed to produce the goods that they buy on a daily basis.
Take, for example, Arizona. The decision to buy locally produced rice may seem to be legitimate in light of the desire to buy local. Unfortunately rice is a water-intensive crop. That is to say that a great amount of water is required to produce a grain of rice. Arkansas, a large producer of rice, gets a much higher amount of rainfall a year. It might make more sense for a consumer in Phoenix to buy rice from Arkansas rather than more locally-produced rice. When one takes water footprint into account it often is better to buy the imported foodstuff.
Adopting efficient technologies like drip irrigation systems and computerized moisture sensors is too expensive for many farmers. The federal government sends mixed signals on conservation: The estimated $263 million the farm bill annually spends to get farmers to save water is dwarfed by the roughly $5 billion it hands out for growing water-intensive crops like rice, soybeans, and cotton, often in parched regions like Arizona.
water footprints of various items from Mother Jones magazine
Microchip 8 gallons
Pint of beer 20 gallons
16 oz. Diet Coke 33 gallons
Cotton T-shirt 719 gallons
Pair of leather shoes 2,113 gallons
Pair of jeans 2,866 gallons
Ream of white paper 1,321 gallons
Midsize car 39,090 gallons
Special thanks to grollen for bringing this topic to my attention.