> 3, 2010 > Water Sustains All

Water Sustains All

05 2011
A landscape of terraced fields (CORBIS)
In Bali, contoured terraces retain the water used in the cultivation of rice, the world’s second-most widely cultivated crop.

Centuries of experience and technological development separate today’s farmer from the first people who scraped a crop from the ground thousands of years ago, but one thing these farmers still share — the need for water. Agriculture consumes about 70 percent of the planet’s fresh water, up to 90 percent in some countries, surpassing industrial and domestic uses by far.

Reliable water supplies will be a critical factor in increasing agricultural production to meet the needs of the world’s expanding population. The challenge will be to extract greater efficiency from every drop. Irrigated land in developing countries will increase by 34 percent by 2030, according to a U.N. Food and Agriculture Organization estimate, but the amount of water used to produce food crops will increase by only 14 percent because of improved irrigation practices.

So how much water does it take to grow food? Obviously different crops have widely diverse needs, but generally, between 2,000 to 5,000 liters of water are required to grow the food that an average person consumes per day.

The U.S. Environmental Protection Agency offers these estimates of the water needed to produce a variety of foods:



 15 liters

4 liters of milk

 1,514 liters

To raise a chicken

 22.71 liters

One serving of fried potatoes

 52.23 liters

One orange

 378.54 liters

One watermelon

 567.8 liters

A loaf of bread

 11.35 liters

One tomato

 132.48 liters

One serving of rice

 454.24 liters

One egg