A potential global water crisis in coming decades could cause UK food prices to "skyrocket" and damage the economy, experts warned today.
A report from three engineering groups predicts that a rising world population, growing demand for water and the impact of climate change will make water more scarce in future.
This could push up food prices, affect economic growth and even spark conflicts, posing a "serious threat to the UK", the study warns.
Water is one of the most undervalued natural resources in the world but it affects national security through its impact on economic growth, food supply and healthcare, the researchers said.
Direct water consumption in the UK is around 145 litres per person per day, but the report raises concerns that we rely on too much "virtual water" embodied in the food, clothes and goods we import.
It claims this hidden water accounts for more than two thirds of the UK's water footprint and is worsening water shortages in other countries.
According to the research, one kilogram of beef requires 15,500 litres of water to produce, more than 10 times that required to grow the same amount of wheat.
A typical cotton T-shirt brought in Britain requires 2,700 litres of water to produce, much of which will have been used in growing the cotton, often in water-stressed areas such as central Asia or Egypt.
When "virtual water" is taken to account, the average daily water footprint of people in the UK is 4,643 litres per person, of which around 3,000 litres is imported, according to figures from environmental charity WWF.
Mike Haigh, one of the engineers involved in today's study, said the reliance on "virtual water" could have a "disastrous" affect on the UK and called for more to be done to raise awareness about the importance of conserving water.
"We think this is an issue that faces poorer nations but it's not. A lot of the United States is under high water stress and the south east of England is not immune to these problems," he said.
"The UK must recognise its own water footprint and how it is exacerbating the water stress in already water-strained countries by importing food, clothes and goods."
Mr Haigh admitted it would be an "uphill struggle" to make people aware that their water consumption was not simply confined to what they drink each day.
Recent wet summers had led people to take warnings about water shortages and climate change less seriously than before, he said.
Professor Roger Falconer, one of the report's authors, said that this meant "people are not thinking about the problems coming our way in five, 10 or 15 years".
He said members of the public needed to be educated so they understood their individual water footprint and urged businesses to look at the use of virtual water in their supply chains in the same way they were now doing for carbon.
Professor Peter Guthrie, the lead author of the report, said: "Our virtual water footprint is critical and we need to give it far greater attention.
"We should ask whether it is right to import green beans - or even roses - from a water-stressed region such as Kenya."
The report concludes that the UK Government should put water at the centre of its international development policy and calls on the UK to take a lead by reducing its water consumption.
It calls for the UK to manage its water more sustainably from "cloud to coast" and declares that water impacts should be considered alongside carbon footprints in the face of climate change.Reuse content