The Telegraph | March 21, 2009
By Harry Wallop

Prof Tim Lang said people needed to wake up to how much water farmers and food factories use in producing staple goods, particularly meat, coffee and milk, saying the threat to Britain's food chain from its water footprint is just as great as its carbon footprint.

A return to rationing, though "almost unthinkable" in peace time, cannot be ruled out, he warns. While such direct Government intervention would be a very last resort, indirect "editing" of people's diets by supermarkets and central Government is essential, he said.

Prof Lang, speaking to The Daily Telegraph on the publication of his latest book 'Food Policy', is mid-way through a project to ascertain what constitutes the perfect "sustainable diet".

His team at City University London is trying to come up with a system to help consumers navigate the minefield of shopping for food that is nutritious, ethical and sustainable.

He is aiming to definitively ascertain whether, for example, a Fair Trade banana from Costa Rica is as "sustainable" as a lamb shank from Wales, or a high-fat ready meal.

Prof Lang, who coined the term "food miles" more than a decade ago, now believes that overuse of water is the biggest threat facing Britain's food chain.

"Huge amounts of water is being used as irrigation or fed directly to animals. It is a nightmare. Water stress is huge across huge swathes of the globe.

"We think that we are liberally supplied by God's water. But that's not true."

According to the World Wide Fund, the production of a simple pint of milk uses up more than 550 litres (968 pints) of water – the equivalent of running six full baths. 

A cut of coffee uses up 140 litres (246 pints), while a hamburger uses an astonishing 1,800 (3,168).

These figures take into account the amount of water used from the start to the end of the food chain, including the irrigation on the farm, the processing of the food, such as washing the coffee beans, and the cooking of the product. Meat uses so much because of the water needed to irrigate the crops that end up as animal feed.

"We cannot carry on consuming the same amount of meat and dairy that we do currently. We are convinced about that now. It is absolutely madness."

Prof Lang backs a call from Australian academics who have called for people to eat no more than 90g (3.17oz) of meat a day – nearly half the current level of 170g that the average British adult consumes.

The UK has become the sixth largest net importer of water in the world, the environment group WWF estimates, with every consumer indirectly responsible for the use of thousands of litres a day. Only a third 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.

While rationing, as experienced during and after the Second World War, is very unlikely, Prof Lang says supermarkets and the Government will need to "choice edit", the products on sale to reduce shoppers water footprint.

"Don't think it doesn't already go on. It is a myth that consumers have free choice," he said, pointing out that food companies frequently change the formula of food to cut out salt or additives – under pressure from campaigners or legislation.

While coffee, African-grown vegetables, milk and meat all use up vast quantities of water, Prof Lang points out that some products are far more "sustainable", including tea, home-grown apples, porridge and British seafood, such as mussels and oysters.

"I have porridge every morning," he said.