Every person in the United Kingdom consumes about 4,500 litres of water a day - that's almost 60 baths full.
This extraordinary figure comes from a report published by the World Wildlife Fund, which makes clear that the overwhelming majority of this water is virtual. That is to say, it is used to produce our food and clothing - much of it in places that already suffer water shortages.
So Britain's businesses and its people are inadvertently contributing to the slow death of some of the world's most iconic rivers.
The report - UK Water Footprint: the impact of the UK's food and fibre consumption on global water resources - says each of us drink, flush and wash our way through about 150 litres of mains water a day. But we use 30 times as much to produce our food and clothing.
Stuart Orr, WWF-UK's water footprint expert, points out that the UK is the world's sixth largest importer of water - only 38 per cent of what we use comes from our own rivers, lakes and groundwater reserves. The remaining 62 per cent is taken from bodies of water elsewhere in the world to irrigate and process food and fibre crops that we subsequently consume.
According to the report, just one tomato from Morocco takes 13 litres of water to grow, while the ingredients in a single cup of coffee collectively use 140 litres.
8,000 litres of water is used to produce just one pair of leather shoes, i.e. amount of water required to grow feed, support a cow, and process its skin into leather.
A shirt made from cotton grown in Pakistan and irrigated with water from the Indus River absorbs 2,700 litres. The river often runs dry before it reaches the sea, affecting communities and habitats in the Indus delta and further endangering species such as the Indus River dolphin.
In India and Pakistan, WWF is working with farmers who grow thirsty crops - cotton, rice and sugar-cane - to explore ways in which they can use less to grow more. Farmers in one sugar-cane trial achieved a 40 per cent reduction in water use while increasing yields by a third.
This thought-provoking report raises a number of questions for those with responsibility for procurement, including:
· How much water are you using in your global supply chain?
· Are you inadvertently adding to the world's water shortage?
· If so, is that environmentally or commercially sustainable?
· Could it cause you production problems in the future?
· Should you start to reduce your water footprint now?
Marks and Spencer is among the first of the UK's major companies to evaluate its water footprint, taking account of the amount it uses directly from the tap and indirectly through its supply chain.
A spokesman said: "We are working with WWF on a series of environmental projects in our supply chain as we look to increase substantially our sourcing of sustainable raw materials.
"We have a particular focus on agriculture, including marine issues and matters related to the use of fresh water."
To download a copy of the full report - UK Water Footprint: the impact of the UK's food and fibre consumption on global water resources - click here