The Hidden Water in a Hamburger: Comparing Food Water Footprints

Every meal contains more water than what appears in a glass. Growing wheat for a slice of bread, raising cattle for a hamburger, and watering vegetables for a dinner plate all take water. All of this happens long before the food reaches a plate. Scientists call this hidden total a food's water footprint. It is the amount of water used, directly and indirectly, to produce a food.

A student named Priya became curious about her own family's water footprint. The idea came up during a class discussion about drought. She decided to compare two common foods: beef and wheat. Her research turned up water-footprint estimates that are widely cited. Producing one pound of beef takes roughly 1,800 gallons of water. This total counts the water used to grow the grain and grass cattle eat. It also counts water cattle drink directly, plus water used to process the meat. By comparison, producing one pound of wheat takes roughly 220 gallons of water. Most of that water is the rain and irrigation water the wheat plants take up as they grow.

Priya's first reaction was disbelief. A pound of beef and a pound of wheat look about the same on a kitchen scale. It was hard to imagine that one required about eight times as much water as the other. She learned that the difference comes mostly from how cattle are raised. A cow does not directly drink 1,800 gallons of water in its lifetime. Instead, most of that total is water used to grow the corn, soy, and hay the cow eats. Cattle eat this feed for months or years before they become beef. So much grain goes into raising each pound of meat that the water used to grow it adds up long before the animal itself drinks a drop.

This pattern is not unique to beef and wheat. Producing meat of almost any kind usually takes more water than producing the same amount of grain, fruit, or vegetables. This is because animals eat crops that themselves needed water to grow. Knowing a food's water footprint does not mean that food is wasteful or that anyone must give up that food. Food choices are also, in a hidden way, choices about how a limited water supply gets used.

Priya's research connected to a bigger number too. Agriculture uses roughly 70 percent of the freshwater withdrawn worldwide, more than industry and household use combined. This estimate comes from the Food and Agriculture Organization and UN-Water. Most of that water goes toward irrigating crops. This includes grain fed to livestock, wheat that becomes bread, and produce on grocery store shelves. In places where fresh water is scarce, farmers and water managers watch closely which crops use water most efficiently. A small change in what gets planted can shift how far a limited water supply stretches.

For her final project, Priya calculated her own family's water footprint for one full week of dinners, using published water-footprint estimates for each ingredient. She was surprised by what she found. Two or three beef-based dinners used more water than all the rest of the week's meals combined, even though those dinners were only a small part of the week's total food by weight. Priya did not conclude that her family should stop eating beef entirely. Instead, she suggested small shifts, such as serving beef less often or choosing smaller portions, that could measurably lower a family's water footprint over a year.

Water footprints are one way to think about a resource that often seems invisible. Once water leaves the faucet or the irrigation canal, it is easy to forget where it goes. A gallon of water used to grow grain for cattle does not disappear, but it is unavailable for other uses while it is tied up in food production. It cannot fill a reservoir or support a river's fish population at the same time. As freshwater becomes more limited in many places, tracking water footprints gives farmers, food companies, and families a clearer picture of where water actually goes on its way to a dinner plate.

1. According to the passage, about how many gallons of water does it take to produce one pound of beef? About how many gallons does it take to produce one pound of wheat?
2. Why does producing beef take so much more water than producing wheat, according to the passage?
3. What percent of the world's freshwater withdrawals does agriculture use, according to the passage? What two organizations does the passage credit for that estimate?
4. Based on the passage, explain in your own words what a "water footprint" means.
5. Why did Priya decide her family should eat less beef, rather than stop eating beef completely? Use details from the passage to support your answer.
6. The passage says water used to grow cattle feed "is unavailable for other uses while it is tied up in food production." Explain what this sentence means. Use an example from the passage.