June 23, 2011

Water Crisis: how much do we need? Practical innovation to solve water shortages globally

An average person in the world uses 1,000 cubic metres a year for growing food, hygiene and drinking – equivalent to 40% of an Olympic swimming pool.  Yet 4,000 children die every day because the water supply is unclean and 40% of the world do not have access to tap water – even though many of them own a mobile phone.

If the poorest nations gain a standard of living equivalent to wealthy nations today, then water demand will be three times the figure of 3,350 cubic kilometres seen in 2000.

The average EU citizen uses 150 litres a day:  33% personal hygiene, 33% flushing toilets, 13% is for washing clothes, 8% for washing dishes.  Some is easy to save:  running a tap while brushing your teeth wastes 5 litres a minute.  The UK could save 180 million litres a year if people stopped– enough to supply 500,000 homes.  That will mean less need to replace leaking pipes, less need to build new reservoirs, less need for desalination to supply London, less energy used to pump, process or treat water.

But 150 litres a day figure jumps to 4,645 or 4.6 tons if we count water to make the food we eat and the products we buy.

•    Tomato                   13 litres
•    Slice of bread          50 litres
•    Orange                    58 litres
•    Egg                       146 litres
•    Pint beer               170 litres
•    Burger               2,400 litres

•    Cotton ball             4.5 litres
•    Sheet of paper      13.6 litres
•    Cotton teashirt    4,000 litres
•    Leather shoes     9,600 litres
•    Pair of jeans      11,000 litres

Much of the this “virtual water”  in your shopping bag is from other nations, because the products were made there, or grown there (see Virtual Water page ff).  Countries like Sweden do not need the additional Virtual Water, but may be adding to pressures on water supplies elsewhere by importing food or cotton, for example, from a very dry nation.
Water saving only really benefits local communities.  It is not as if Sweden can start exporting water to Northern Africa, and water savings in Stockholm cannot even be traded effectively as Virtual Water (see page dd to gg), unless the extra water in Sweden can be used to create more food or produce more products in the country.  So in water-rich nations, the main reason to save water is to save energy in treatment and pumping, and use of chemicals such as chlorine.