Much has been made in recent months of carbon footprints, yet what about our impact on water consumption? This month Waterwise, an independent, not for profit, non-governmental organisation focused on decreasing water consumption in the UK, released a report, called Hidden Waters, looking at consumers’ "water footprint". It assesses the effect of water consumption and embedded water – the true value of how much water has been used to produce a product or service.
The Earth’s surface is covered mostly by water, but resources are dwindling and less than 1% of the globe’s water is easily accessible freshwater for human consumption. Yet this is unevenly distributed in space and time, and is sometimes polluted; more than 1 billion people still lack access to improved water supplies, and one-third of us already live in "water stressed" areas.
Though we might envision our nation as lush and rainy, we are not immune from water scarcity problems, experiencing some of our worst droughts ever in recent years. If present consumption continues, two-thirds of the global population will live in areas of "water stress" by 2025. Increasing human demand for water coupled with climate change means the future supply is not secure, but proper water management can help.
Water consumption in many nations is around 90 litres per person a day, but the average Briton uses 150 litres daily. The average Briton drinks about two to five litres of water a day, and uses another 145 or so litres for cooking, cleaning, washing, and flushing. Yet, multiply that by 23 to reveal the average person’s consumption: more than 3,400 litres a day because it includes the embedded water in all that we consume.
Water is everywhere: in cars, clothing and food. According to a 2004 Unesco-IHE report, it takes about 140 litres to grow a cup of coffee; about 11,000 litres to produce a pair of jeans; and about 400,000 litres to build a car. In the UK, agriculture accounts for only about 3-15% of freshwater abstractions; industry and households are the major users. And our water footprints extend beyond the UK, so consumption affects water supplies elsewhere in the world. Around 70% of the UK’s water footprint is external, meaning that along with the products that we import, we are also importing embedded water.
About 65% of water consumption is hidden in food because it takes huge volumes of water to cultivate food, and then much more to feed and service the animals we eat. Animal products almost always have a higher embedded water content than crops because it takes huge quantities of water to grow feed. And some plants are particularly water intensive such as cotton, rice and coffee.
To produce 1 kilo of wheat about 1,000 litres of water are needed, but for beef about 15 times as much is required. That said, carnivorous diets are unavoidably more water- and land-intensive than low-meat or vegetarian diets. It is estimated that if the world were to adopt a Western-style diet, 75% more water would be necessary for agriculture.
Industrial products, too, contain embedded water. Globally only about 20% of the world’s freshwater withdrawals are for industrial use, but here in the UK about 45% of our freshwater is withdrawn for use in industry. A microchip may contain 32 litres of water embedded in it. But the amount of water embedded in industrial goods varies from product to product and also from make to make.
Just as the amount of water embedded in industrial goods varies, so too does it differ for agricultural products. A kilo of oranges from the US has about 175 litres of embedded water but a kilo from Australia has over three times more. Embedded water content varies between and also within nations owing to differences in climate, irrigation, production techniques and technology. Furthermore, different species of the same plant may also differ in water requirements. Maris Piper potatoes, for instance, require much more water than Desiree potatoes.
As customers we do not have much control over the amount of water embedded in our food, unless we alter our diets. But we should not have to make these changes yet, since there are many steps that farmers, water managers, and governments can take to ensure that the water used to grow our food is efficiently used. But we must encourage our leaders to take these steps. And we must tell our retailers and manufacturers that we want to know how much water is embedded in what we buy.
According to the United Nations Environment Programme, every person on Earth had about 9,000 cubic metres of freshwater available to them 20 years ago; ten years later this figure was down to about 7,800 cubic metres. By 2025 it is expected to fall even more – to about 5,100 cubic metres.
By considering the amount of embedded water in products, we may be able to collaborate to increase the world’s water use efficiency. Some experts say that trade with consideration of embedded water may allow dry nations to ease pressure on local water supplies by importing water intensive goods. While there may be an opportunity for action on a global scale, there is also plenty of opportunity in the UK. So goes the old adage/ think globally, act locally.
By making a few simple efforts, we can all reduce the amount of water that we waste. If we turn the tap off while we brush we save about five litres each time; when we fix a leaky tap we save more than 3,000 litres each year; and when we hold on to that cotton T-shirt for another year, we are saving another 2,500 or so litres.
•Joanne Zygmunt, head of research at Waterwise, contributed to this week’s Trends Insight