Water water everywhere
March 04th 2008 At first glance,water seems to be a fairly simple concept- we see it fall from the sky, fill our rivers and flow out of the tap. If one looks a bit harder, however, one realizes that water is hiding all around us. It may be difficult to see but water, more specifically embedded water, lurks behind all products from cars, computers and shoes to sandwiches, crisps and lager
This hidden water is known as embedded water. Embedded water is the amount of water used to produce a product. Each Briton uses about 150 litres of tap water a day, but if you include the amount of water embedded within products, our water consumption increases to about 3400 litres a day. Where then does all this water come from? There are many factors which influence how much water is embedded in a product: climate (growth conditions), yield, crops species requirements, methods and technology, and irrigation efficiency are only a few.
It takes 200,000,000 litres per second to grow food for the planet. This totals about 65 percent of the water that we consume. To produce one 150 gram burger takes a staggering 2400 litres. This number consists of the water needed to grow about 10,000 kilos of feed for the cow, the water necessary to supply that cow with drinking water and the water used for cleaning the cattle farm. This total does not even begin to take into account the amount of water embedded in processing, packaging, and transporting the beef. To produce one pint of beer takes 170 litres of water. A tomato has about 13 litres of water embedded in it; an apple has about 70 litres. It takes about 136 drops of water to produce one drop of tea, and about 1100 drops of water to produce one drop of coffee.
Not only does the amount of water embedded in products vary, but so too does the type of water embedded. The first type of water, called ‘blue water’, refers to surface and ground waters- it is what we see flowing in our rivers and it is easily extracted. The second type, ‘green water’, is water stored in the soil as moisture. Unlike blue water, green water can not readily be seen and is thus often overlooked.Yet green water is essential for vegetal growth, both natural and cultivated, and the vast majority of the world’s crops are grown using only green water.Without green water,we would have to rely solely on blue water sources- our already water-stressed rivers, lakes and aquifers - to irrigate all of our food.
In the wake of climate change, this proves greatly unnerving. As the climate alters, rainfall patterns will change, leaving us unable to rely on nature to irrigate our unnaturally large plantations and resulting in an increase in irrigated land. This increase means less available water for the environment and for human use, particularly in areas of water stress where there is often a cheap labour market. Inevitably, this will result in an influx of cheap products into first world countries whilst small scale subsistence farmers and low income families struggle to make a living and are denied access to water.
Additionally there are potential issues over importing and exporting embedded water. International trade makes waters everywhere a resource shared by all - at least 1000 billion cubic metres of embedded water flow around the world every year, the majority of which (about 80 percent) is embedded in agricultural goods.
It is thus obvious that our consumption has serious effects on water resources all over the world, not just here in the UK. About 70 percent of the UK’s water footprint is external, meaning that along with the products that we import we are also ‘importing’ embedded water. Whilst we import goods which require water for production, we annually import millions of litres of embedded water from places as close as Spain to as far away as Brazil. The UK regularly draws on the Nile’s waters as we import cotton and other products from Egypt. Furthermore, many of the countries which export products containing immense amounts of embedded water are some of the driest countries in the world. It could therefore be the case that our consumption here in the UK is draining lakes, rivers, and aquifers in other, drier nations.
We too, of course, are exporting our own waters as well. Water from the River Thames is shared by the world when it is used to make products for export.
The issue of embedded water proves that water is not as simple a concept as it may seem. The foods we eat, the clothes we wear and the cars we drive, all contain hidden water. As global trade and water consumption increases, it will prove vital for embedded water fluxes to be assessed at an international, global level. If present levels of consumption continue, two-thirds of the global population will live in areas of water stress by 2025. International, political discussions regarding water will be crucial in the upcoming years and embedded water, the mysterious water in hiding, must be taken into consideration if we are to efficiently assess and safeguard our water supply for the future. More articles from Waterwise: |
