Food waste is a staggering problem. In 2010, close to 133 billion pounds, or a little over $160 billion worth of food, wound up in U.S. landfills.

“There’s no benefit to wasting food,” says Kai Olson-Sawyer, a senior research and policy analyst at GRACE Communications Foundation, an organization that highlights the relationship between food, water and energy resources. “The fact is that food waste is truly a waste to all humanity of every kind.”

That’s because when you toss a rotten apple or a moldy container of leftovers, you’re not just throwing away the food, but all the resources that went into producing it. “It’s really important to understand where and how things are grown,” says Ruth Mathews, executive director of the Water Footprint Network, an organization founded in 2008 to advance sustainable water use.

Water plays a major role in food production, and as a result, food waste translates to an enormous amount of water wastage. All foods have a water footprint, the direct and indirect water that goes into producing a certain food—although some footprints are larger than others.

In general, meats tend to need the most water for production, primarily because of the amount of food the animal needs. So for instance, the water footprint of beef includes water that’s used to grow the animal’s feed and to maintain the farm, as well as drinking water for the animal.

Also, larger animals aren’t as efficient in terms of meat production as smaller animals like chickens or turkeys, and the bigger beasts therefore have a larger water footprint. Consider this: The water footprint of beef adds up to 1,800 gallons per pound—think 35 standard-size bathtubs—while a chicken’s water footprint is roughly 519 gallons per pound.

Almonds, too, have a massive water footprint—it takes more than 2,000 gallons of water to produce a pound of almonds—and have been in the news lately for their water-guzzling ways. But it isn’t as simple as that when you account for the amount of food wasted.

“When food is wasted, it’s often because of how we prepare it or how perishable it is,” Olson-Sawyer says. “For instance, almonds tend not to spoil as quickly as milk, so less is wasted.”

In 2010, Americans wasted 23 percent of every pound of beef, which accounted for 400 gallons of water that, quite literally, went down the drain. In general, fruit, vegetables and dairy account for the most consumer waste. Also in 2010, consumers wasted 25 percent of every pound of apples, which ultimately translated to 25 gallons of wasted water.

Similarly, it takes roughly 620 gallons of water to produce a dozen eggs, which means that each time we dump an unused egg in the trash, we waste about 50 gallons of water.

Food waste has other environmental impacts, too. “If you put all the food waste into one country, it would be the world’s third largest greenhouse gas emitter,” says Brian Lipinski, an associate in the World Resource Institute’s Food Program. Decomposing food that makes its way into landfills releases methane, which is significantly more harmful to the environment than carbon dioxide.

All is not lost, however. There are numerous efforts underway to cut food loss at every level. The U.S. Department of Agriculture and the Environmental Protection Agency recently called for a 50-percent reduction in food waste by 2030. Meanwhile, Portland launched a citywide composting program a few years ago, and at the retail level, the former president of Trader Joe's recently opened a store near Boston that sells surplus food donated by grocery stores at rock-bottom prices.

Even simple changes can have big effects. A few years ago, college cafeterias across the U.S. began to go trayless. Carrying two plates at most rather than trays piled high with all-you-can-serve and all-you-can-eat daredevilry forced students to think about what they really wanted to eat. The seemingly simple move, which more than 120 colleges chose to adopt, helped reduce food consumption and waste by 25 to 30 percent in some colleges.

Still, waste is inevitable. “There’s never going to be some ideal or perfect way to eliminate it all, but it’s pretty egregious right now,” Olson-Sawyer says. More so, perhaps, because according to the United Nation’s World Food Program, “there’s enough food in the world today for everyone to have the nourishment necessary for a healthy and productive life.”

Fortunately, change at any level—whether it’s as a supplier, retailer or consumer—will help ease the impact of food waste on natural resources. Simply put, “it does matter how much you consume,” Mathews says. “It does matter what you consume, especially when you get down to the details of where this is produced and how sustainable is that production.”