How Much Water Goes Out With the Trash Each Year?

Oranges rotting on a London market stall. Wasting food leads to the waste of huge quantities of water. Photograph: Martin Godwin via guardian.co.uk

As consumers throw millions of tonnes of uneaten food into the bin each year, few give a thought to the hidden cost of such waste – the water that it took to grow the food.

But new research shows that we throw away, on average, twice as much water per year in the form of uneaten food as we use for washing and drinking.

What is worse, increasing amounts of our food comes from countries where water is scarce, meaning the food we discard has a huge hidden impact on the depletion of valuable water resources across the world.

According to the first comprehensive study into the impact of the "embedded water" in the UK's food waste on world water supplies, more than a 5% of the water used by the United Kingdom is thrown away in the form of uneaten food. While these figures deal with the UK, I'm sure the numbers are indicative of most of the first-world countries; and, possibly some of the second-world countries as well.

The research was carried out by the government's Waste and Resources Action Programme (Wrap) and the green campaigning group WWF, and is published with the title: Water and Carbon Footprint of Household Food Waste in the UK.

The water used to produce food thrown away by households in the UK amounts to about 6.2bn cubic metres a year.

That represents 6% of the UK's total water footprint, which includes water used in industry and agriculture.

About a quarter of the water used to grow and process the wasted food originates in the UK, but much of it comes from countries that are already experiencing water stress.

Green campaigners have for years called for more attention to be paid to "hidden" or "embedded" water – water that is used in the production of all sorts of goods, from food and clothing to cars and furniture, and which represents a hidden cost on exports.

As more countries suffer from water scarcity, these exports can further deplete natural resources and cause environmental problems such as salination – which can render land unfit for growing crops – and higher prices for water to poorer consumers.

Food waste carries another environmental cost: it accounts for about 3% of the UK's annual greenhouse gas emissions, equivalent to the amount generated by 7m cars each year.

That is enough to cancel out the greenhouse gases saved each year by British households' recycling efforts.

Liz Goodwin, chief executive at Wrap, said: "These figures are quite staggering. Although greenhouse gas emissions have been widely discussed, the water used to produce food and drink has been overlooked until recently.

"However, growing concern over the availability of water in the UK and abroad, and security of the supply of food, means that it is vital we understand the connections between food waste, water and climate change."

She said the organisation – which is threatened with budget cuts – would work further with retailers, food and drink companies and local authorities to reduce the amount of food wasted.

David Tickner, head of freshwater programmes at WWF, said consumers could make a "small but very significant" contribution to reducing water stress if they tried to avoid wasting so much food.

Food Normally Wasted Feeds 5,000 a Curry Lunch

Waste food feeds 5,000 hungry participants a tasty curry lunch in Trafalgar Square in London. Photo courtesy: Adrian Brooks/ImageWise via guardian.co.uk

Elona Grondona, a school nurse, came to Trafalgar Square in London for one reason – to eat curry. But this was no ordinary meal, Friday's lunch was served as part of the Feeding the 5,000 initiative, to encourage households and business to reduce food waste.

The Feeding the 5000 team – a coalition of Fareshare, FoodCycle, Love Food Hate Waste and Friends of the Earth, led by food waste expert Tristram Stuart– treated Grondona and 4,999 others to a free meal using food that would otherwise have been wasted, such as cosmetically imperfect fresh fruit and vegetables – in short, wonky carrots.

The misshapen ingredients were not salvaged from nearby skips but supplied directly by farmers who sell their goods to supermarkets. "The supermarkets have strict cosmetic standards, so if a carrot is too long or slightly bent, it either goes in the bin or is left out in the field and simply ploughed back into the ground," Stuart says. "Today, that's not happened and all that food is here to be eaten."

While UK consumers cannot access farmers' surplus produce, Stuart hopes the event will inspire people to stop wasting food and to demand businesses end the practice of dismissing unsightly goods. Some supermarkets tried selling ugly vegetables in 2008 after an EU ruling meant odd-shaped and oversized produce could be sold in the UK.

As well as the 5,000 portions of curry on offer, a live cooking tent was showing the public how to cook and eat discarded bits of animals such as hearts, lungs and offal (offal consumption has apparently halved in the UK during the past 30 years). There were also 1,600 pints of apple juice ready to be drunk and celebrity chefs turning waste into well-seasoned goodies.

"It's a fantastic idea," Grondona says. "Children aren't getting enough quality food and obesity is a major issue. If the government cannot afford to provide free school meals for everyone, then why not find a way to get all this healthy food that's being wasted delivered to schools and help cut down the nation's obesity rate? If all the food that's here today was destined for landfill, something is seriously wrong with our society."

The cries of "free lunch, free lunch" from the organisers, who had spent all morning distributing 17,000 flyers, clearly had an effect – Trafalgar Square was swamped with people. When the London mayor, Boris Johnson, arrived to dish out the first portion of free curry the area suddenly turned into a giant rugby scrum.

Johnson, who tucked into a hearty portion of curry while posing for photos, has been working with the London Food Board to raise awareness of waste. He is urging businesses and the public to sign a "Food Waste Pyramid" pledge to reduce the mountains of food needlessly thrown away. He said enough food to fill 11,720 double decker buses, or the Albert Hall 15 times over, is binned every year in London.

"Throwing away mountains of perfectly edible food is crazy at a time when all Londoners are feeling the pinch," Johnson said. "I want to do all I can to help people to cut waste, save cash by doing so and improve our great city. This is why I am determined to cut the amount of food needlessly sent to landfill. I urge businesses and Londoners to get on board to reduce waste and help to save millions for the capital's economy."

Johnson's food waste pyramid asks businesses to avoid buying surplus food, redistribute any unwanted food to charities, and pass food unfit for human consumption to livestock. Waitrose, New Covent Garden Market, Cafe Spice, Wahaca, Innocent drinks and Abel & Cole have already signed up.

So how was the food? The curry, bursting with potatoes and cauliflower, was nutritious and tasty – if a little underseasoned – with not a crumpled carrot in sight. It could have been a bit hotter, but you can't expect 5,000 people to like their food fiery. Out of sight of Stuart, I gave the offal a miss.

Stuart, who published Waste: Uncovering the Global Food Scandal in 2009, hopes that if enough members of the public sign up, more businesses will follow and western countries will stop wasting up to half of their food, reducing pressure on the environment and global food supplies.

"Around 80% of people want to see businesses cut food waste," Stuart says. "We can do it together. People can say 'I'm going to cut food waste' and business will do the same and it can become a shared responsibility. There is nothing wrong with the fruit and vegetables we're throwing away. We want to see whole animals are eaten from nose to tail, so that wonky parsnips are eaten rather than thrown away, so that people can pick an apple from a tree and press it for juice themselves rather than walk past it and buy juice from Tesco."

Grondona travelled from Surrey to lend her support to the event but others came from further afield. Maria, a 23-year-old dancer from Valencia, is on holiday in the UK and was handed a leaflet while queueing to enter a nearby exhibition. "This is good food," she says, spooning rice and potato into her mouth. "It's amazing that these people have given up their free time to feed us. I haven't seen this happen in Spain."

Lesley Peyer, from Salisbury, was celebrating her 60th birthday with her daughter. "We've become a very wasteful society," she said. "It's surprising how many people are obese in this country, and I think it's more important than ever that people understand what food they eat."

Perhaps the last word should go to one of the many children attending the event, some of them invited by the charity School Food Matters. Daniel Friend, 12, from Golders Green, said: "I totally agree that we shouldn't waste food. We should eat it ourselves or give it to animals. It makes the bins stink too."