Water footprints

There is plenty of water on Earth, but most of it is salty. Humans can’t really use salt water for hygiene, cooking, or drinking. We need freshwater for practically everything we do. So, when we talk about water use, we mean freshwater. How much freshwater do you think you use?

You use water to brush your teeth, take a shower, flush the toilet, and do laundry. You also need water to do the dishes, and water your plants. Pets need water too. And there is obviously the water you drink. It might be hard to tell how much water all these activities consume.

But there is often a small device somewhere in your home that measures how much water has been used - a water meter. A water meter can only measure water used by appliances in your home - for example by a washing machine, or when you turn on the tap, or flush the toilet. This is direct water consumption. But we actually use plenty of water indirectly. This is all the water “hidden” in the products we buy and use - our food, clothes, books, furniture or mobile phones.

Water is used in some way or another, to produce nearly everything around us. The water used by industry can be divided into three different types of water. When agriculture uses rainwater it’s called green water. Green water is mostly used for growing crops or forestry. Another type of water, is called blue water.

This is groundwater or surface water from lakes or rivers. Some industrial processes also pollute water with chemicals. Water affected by pollution is called grey water. Let’s look at some examples of how water is used! In many areas, crops are grown using mostly green water.

But this is not always enough, so farmers might need to water additionally - using blue water from lakes, rivers, or wells. If farmers also use chemicals such as pesticides or fertilizers that cause pollution, this might result in grey water too. All the water involved in making a product - green, blue, or grey - is the product’s water footprint. Every product has its own water footprint. For instance, growing an orange uses on average 80 litres of water, while a banana uses about twice as much.

The production of meat and dairy has an even higher water footprint: to produce a glass of milk takes more than 250 liters of water - that’s about 1000 glasses of water! And producing one beef burger requires nearly ten times more water than that! Not just food, but everything is made using water in one way or another. A single sheet of paper requires about 10 litres of water, a cotton T-shirt about 2500 litres, and a mobile phone as much as 12000 litres of water! If you add up the water footprints of all the items you buy and use, plus your direct water consumption, you can calculate your own personal water footprint.

And if you do that for everyone living in a country, you will get the country’s national water footprint. If you are interested in the water footprint of different items, you can look this up on the Internet. Water is one of the most important resources on Earth. Every decision you make - what you eat, what you wear, or how long you shower - has an impact on how much water is used. Be aware of water footprints!

It can help us use water responsibly.