By Jane Nethercote|
Mar 26, 2007 12:00AM |EMAIL|PRINT
So you think that your shower bucket is saving the planet. Think again. Most of your water waste is around your waist.
Through eating and drinking, the average Briton consumes about 3,400L of water a day, according to Hidden Waters, a recent report from Waterwise. Australian irrigation scientist Professor Wayne Meyer reckons it’s more like 3,000L per meal, or 10,000L of water a day in the Western world.
Everything you eat and drink contains “embedded water” – the so-called hidden water it takes to bring produce from the field to your table. But not all foods are created equal. It takes a lot of water to grow food, and then “much more water to feed and service the animals that we eat”, says Waterwise’s head of research Joanne Zygmunt.
Which means vegetarians have a right to feel smug: a leafy diet contains about half the embedded water content of a meat-lovers regime. Not that anything is ever that simple. There’s methane output too of course, and here, some might venture that vegetarians are bigger contributors.
Natural rainfall (green water) plays a large part in embedded water content – only 15% of crops produced worldwide are irrigation-fed — but 70% of global freshwater withdrawals are for irrigation (blue water). And in Australia in 2003-04, the most extensive use of irrigation in agriculture was for pasture for grazing (ABS), not for crops. Despite being the driest continent on earth, Australia is a net exporter of embedded water. Water that we don’t have.
So how do you trim your water use? The Crikey Water Diet can help. Our motto: A moment on the lips, a life of bucket trips.
To kick off, here are some general rules, with expert commentary from Kelvin Montagu of the Cooperative Research Centre for Irrigation Futures.
Find food close to the source. “The closer your food is to the source of all food, photosynthesis, the less hidden water you will be using. All the food we eat is originally produced by plants as they grab carbon dioxide out of the air and produce sugars via photosynthesis, losing a lot of water in the process.”
Green should be seen. “If you are dead keen on reducing the amount of hidden water in your food then eat leafy vegetables. By doing this you minimise the amount of food value lost as the original sugars are changed to more complex foods – but there is a limit!”
Fruits and grains reduce the pain. “The next best is to eat fruits and then grains which will have more hidden water than vegetables. This is because there is a cost to the plant in transporting, making new more complex compounds and storing them in the fruits and grains.”
If it moves, lose it. ”The real big jump in hidden water comes when another animal gets involved. A lot of the food values are lost in the conversion of the original plant into the products from animals such as cheese, eggs and finally meat.” It’s estimated that one kilogram of beef has 50,000-100,000L of embedded water, more than a backyard pool, as Des Houghton notes in the Courier-Mail.
Where did it come from? There are many variables in food production and embedded water can vary significantly depending on country (or even region), as well as the aridity or humidity of the atmosphere. A kilogram of tomatoes produced in the UK has an average embedded water content of eight litres, but a kilo from Indonesia contains about 340 litres.
Hidden Waters provides a useful starter table: Global average embedded water content of some major agricultural products (Data from Chapagain and Hoekstra 2004). Caffeine addicts may want to look away now.
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Tomorrow, we’ll bring you The Crikey Water Diet meal plan. Plus we’ll answer such tricky questions as: What can I do if I binge on beef? Which are the best foods to eat? Is chocolate verboten? What about gourmet cheeses? Where should my food come from?