The Water You Never See: The Water Footprint of Everyday Foods

When you think about how much water you use in a day, you probably think about the obvious things.

A morning shower. A pot of coffee. Running the dishwasher. Watering the garden.

But some of the largest amounts of water associated with our daily lives are completely invisible. They're hiding in our food.

What Is a Water Footprint?

Almost everything we eat requires water long before it reaches our plate.

Crops need rain or irrigation. Animals need drinking water and feed. Water is also used during processing and production.

Add it all together and you get what's known as a water footprint—an estimate of the total amount of freshwater used throughout the production of a food or product. And some of the numbers are remarkable.

How Much Water Is Hiding in Your Kitchen?

Consider your morning cup of coffee.

Growing the coffee plant, harvesting and processing the beans all require water. When the entire supply chain is considered, a single cup of coffee can represent roughly 140 litres of water.

The amount you pour into the coffee maker is only a tiny part of the story.

Chocolate is another fascinating example. Producing a kilogram of chocolate can have a water footprint of approximately 17,000 litres.

And then there's beef. Depending on where and how it's produced, estimates commonly put the global average water footprint of beef at around 15,000 litres per kilogram.

Before you imagine a cow drinking thousands of litres of water, however, there's an important detail. Most of that water isn't coming from a hose.

Not All Water Is the Same

Water-footprint calculations generally divide water into three categories. Green water is rainwater stored in the soil and used by plants.

Blue water is freshwater taken from rivers, lakes and groundwater for irrigation, livestock and production.

Grey water is an estimate of the freshwater required to dilute pollutants associated with production to accepted water-quality standards. This distinction matters.

For something like beef, a substantial portion of its estimated water footprint can be rainwater used to grow grass and other feed crops.

So saying that a hamburger “uses thousands of litres of water” doesn't mean thousands of litres of drinking water were poured into producing it.

The real story is more interesting—and more complicated.

A Few Surprising Comparisons

Different foods can have dramatically different water footprints.

A kilogram of potatoes may represent a few hundred litres of water, while a kilogram of rice can require several thousand.

Coffee and chocolate can be surprisingly water intensive because of the agricultural conditions and processing involved in producing them.

Even two identical foods can have very different footprints depending on where they're grown, how they're grown, the climate and whether the crops rely primarily on rainfall or irrigation.

That's why water-footprint numbers are best viewed as estimates rather than precise measurements.

Your Lunch Has Travelled Through the Water Cycle.

Perhaps the most fascinating part isn't the size of the numbers at all. It's where the water comes from.

The sandwich sitting on your plate connects you to rainfall, rivers, soil and groundwater in places you may never have visited.

Your coffee might connect your kitchen to rainfall on a farm in Colombia or Ethiopia. Your chocolate may begin with a cacao tree growing in West Africa or South America.

The wheat in your bread may have depended largely on rainfall thousands of kilometres away. We don't just import and export food.

In a sense, we also move “virtual water” around the world—the water embedded in everything required to produce those foods.

Water Is an Ingredient in Almost Everything

We tend to think of water as something we drink, cook with or wash with. But its role in our lives is much larger.

It's in the fields that grow our food, the feed consumed by livestock, the factories that process ingredients and the enormous global supply chain that eventually delivers dinner to our tables.

So the next time you make a cup of coffee, slice into a chocolate cake or sit down for dinner, consider the water you can't see.

There may be far more water on your plate than there is in your glass.