Do you know the water footprint of these common foods?
It doesn't take too much thinking to realise that both crops and animals being raised for food need water to survive long enough to make it to your plate - but do you know how much?
What is water footprint?
Calculating the ‘water footprint’ of food is a way of measuring how much water was used to produce it.1 If you’ve ever tended to a garden, or even just a houseplant, you’ll know that plants need water. The crops that we grow to eat are no different. Though different varieties need differing amounts, all need water to survive and make it to our plates (and stomachs).
The animals we raise for food drink water too – though most of the water footprint of a steak, for example, comes from the plants grown to feed cattle, rather than water being gulped down by the cows themselves.
Water is also used in the processing of food after it’s grown. It can take 2kg of water to rinse a single kilogram of lettuce, for example.2
Beef is the most water intensive food
The food that needs the most water to produce is bovine meat, such as beef, at over 15,400 litres of water per kilogram.3 Other meats, like lamb, goat, pork and pig meat use between 6000-9000 litres of water per kilogram.3 Chicken ranks the lowest compared to other types of meat, at just 4500 litres of water per kilogram meat.3
The water footprint of meat in general is higher than plant crops, because of all the plants that need to be grown in order to feed these animals.
Dairy has a high water footprint
Because dairy is an animal product, it also has a high water footprint. It takes more water to produce a kilogram of butter (at around 5500 litres) than it does to make a kilogram of chicken, for example.3
Milk fares a bit better: it takes around 1000 litres of water to produce a kilogram. Making cheese uses a lot of milk, so its footprint is higher, at around 4000 litres per kilogram.4
Plant-based foods are not off the hook
Pulses and nuts also need lots of water in order to make it to the dinner table. On average nuts have a water footprint of around 9000 litres per kilogram. Pulses come in at around 4000 litres.3
For those in need of good news, you should know that vegetables are the shining stars of water consumption, averaging just 300 litres of water per kilogram.3 Fruits come in a little higher at 900 litres.3
Making fair comparisons
It’s worth thinking about how much of each foodstuff we tend to use when comparing water footprints.
For example, a kilogram of milk is roughly equal to a litre – an amount some people could easily drink over a couple of days. A kilogram of butter would, however, take a lot longer for most people to eat. Even though butter’s water footprint is higher by weight, your personal water footprint could be affected much more by gulping down milk compared to using a little butter on your toast.
Another way is to compare foods based on the amount of water used per gram of a specific nutrient. Butter actually has just half the water footprint than most oil crops when you look at it this way, at 6 litres of water per gram of fat, versus 11 litres for oil.3 And per gram of protein, beef has a water footprint 6 times larger than that of pulses.5
Finding ways to use less water
The amount of freshwater available on Earth is limited at 2.5%.1 Global water scarcity and a growing world population with more mouths to feed than ever, means we urgently need to find ways to use less water.
Some researchers are using bioengineering to create crops, like new varieties of rice, that need less water in the first place.6 Another innovation uses satellite images to monitor water loss from agricultural land, to help farms figure out how much water their crops need to stop wasteful overwatering.7 And researchers are also coming up with new ways to clean water after it’s been used to rinse produce, so it can be recycled.2
Are there any dietary changes you’re making to reduce your personal water footprint? Let us know below!