Next time the person sitting across the table from me jokes about my tendency to finish every last bite, I will be able to defend my gut reaction to not waste food. (After I’m finished chewing, of course.)
Recent studies now quantify the water and energy costs of discarded and spoiled produce, grains, meat, and dairy.
Experts weighing in at World Water Week in Stockholm estimate that half of the irrigation water used around the world is lost to wasted food–the equivalent every year to half of Lake Victoria, Africa’s largest lake, or 365 trillion gallons (1,380 cubic kilometers).
In the U.S. alone, we throw away or waste about 30 percent of our food, or about 11 trillion gallons (40 cubic kilometers) of irrigation water, according to a report distributed at the conference on the water footprint of food waste.
This would be enough household water for nearly 300 million Americans a year, according to National Geographic water footprint calculator estimates.
“The amount of water that can be saved by reducing food waste is much larger than that saved by low-flush toilets and water-saving washing machines,” the report, published by the Stockholm International Water Institute (SIWI), states.
Food waste is largely a result of inefficient harvesting, transportation, storage, processing, and packaging. The waste tends to be highest in developed countries with large urban populations, according to SIWI.
Nearly 4,600 kilocalories of food per person a day are produced in the field worldwide, but after you account for crops fed to animals, and losses through harvesting and distribution, and at home, there are only 2,000 kilocalories of food per person a day available for consumption around the globe.
The average hamburger requires 630 gallons (2,400 liters) of water to make, when you account for the irrigation of cattle feed crops, as well as water used in production. (More support for Meatless Mondays.) A cup of coffee takes 37 gallons (140 liters) of water.
Understanding supply chain losses is critical to solving the problem, says Arjen Hoekstra, director of the Netherlands-based Water Footprint Network, the nonprofit and academic institution that pioneered the water footprint concept.
“We know relatively well how crops are produced and the water needed to produce them, but we have less data about how much ends up in our stomach,” Hoekstra told National Geographic News. “Wastes occur all over the supply chain, at the field, in transport and processing, and finally at home. The longer the chains, the more waste.”
SIWI sees opportunities for reducing waste by improving water efficiency in the field through better rainwater capture and use methods. There are also more efficient irrigation technologies that could be installed, with funding and technological assistance. The Institute also advocates for food prices that reflect the true cost of production. But the key, according to SIWI, is more awareness–among the public, farmers, and business–about water inefficiencies in agriculture, which uses 70 percent of all available freshwater, and the competition for increasingly scarce water among, farms, factories, growing cities, and the environment.
Nearly 1.4 billion people live in areas where there is not enough water to meet individual, industry, energy, and agricultural needs, according to the report.
“We need to eat in ways that save our health, ours and the environment,” 2008 Stockholm Water Prize winner John Anthony Allan said today during a World Water Week session on the future of water. Allan is the father of “virtual water,” a building block of water footprint calculations.
The energy required for food production, transportation, processing, sales, storage, and preparation was between 8,000 and 9,000 BTUs in 2007, or about 2 percent of American annual energy consumption. And 30 percent of this is thrown away with our food.
The energy footprints used in this analysis did not include energy used to pump, distribute, and treat any water used in irrigation or processing, according to co-author Michael Webber, a professor of mechanical engineering at the University of Texas-Austin’s Center for International Energy and Environmental Policy.
Tasha Eichenseher is the Environment Producer and Editor for National Geographic Digital Media. She has covered water issues for a wide range of media outlets, including E,The Environmental Magazine, Environmental Science & Technology online news, Greenwire, Green Guide, and National Geographic News.
[This post has been reformatted for Water Currents.]