The scale of British water consumption and its impact around the world is revealed in a new report today by the WWF, which warns of the hidden levels needed to produce food and clothing.
The UK has become the sixth largest net importer of water in the world, with every consumer indirectly responsible for the use of thousands of litres a day. Only 38% of the UK's total water use comes from its own resources; the rest depends on the water systems of other countries, some of which are already facing serious shortages.
Average household water use for washing and drinking in the UK is about 150 litres a person daily, but we consume about 30 times as much in "virtual water", used in the production of imported food and textiles. Taking virtual water into account, each Brit soaks up 4,645 litres a day;
Only Brazil, Mexico, Japan, China and Italy come higher in the league of net importers of virtual agricultural water. People in poorer countries typically subsist on 1,000 litres of virtual water a day;
With modern patterns of consumption, businesses and consumers are inadvertently contributing to the slow death of some of the world's most important rivers, the charity warns, and we may not be able to depend on the same supplies in the near future.
British retailers are already examining how much of their food comes from areas where water reserves are depleted and whether they will need to relocate some of their production as water runs out.
The WWF report identifies Spain, northern African countries including Egypt and Morocco, South Africa, Israel, Pakistan and Uzbekistan as countries which face acute water stress and yet supply the UK with substantial exports of their water.
Most British supermarkets currently depend on southern Spain for salad crops, such as lettuce, cucumbers, tomatoes and peppers, as well as broccoli out of season through the winter months.
But over-extraction of water for horticulture and the tourist industry have led to a crisis here. Aquifers have become severely depleted and the water table has been infiltrated by the sea. There are massive challenges with water in places like Murcia. We have to look at least 10 years ahead in terms of security of supply. Murcia will have to look very different in five years' time.