NSW Department of Primary Industries
Science Alert 14 Oct 09;
First we were measuring our ecological footprint - the area of land and resources it takes to support our lifestyles.
More recently we heard about our carbon footprint - the amount of carbon we emit in our activities.
Now, welcome to our water footprint, the total amount of fresh water used to produce the goods and services we consume.
The Netherlands-based Water Footprint Network has calculated that it takes 75 litres of water to produce one glass of beer, with most of the water used in producing the barley for the beer.
To produce one A4-sheet of wood origin paper uses 10 litres of water in growing the tree and making the paper.
Water footprinting has huge implications for agriculture because around 70 per cent of fresh water is used to produce our food.
According to the Water Footprint Network it takes 3400 litres to produce one kilogram of rice, 1800 litres for one kilogram of soybeans, 1300 litres for one kilogram of wheat, 1000 litres for one litre of milk, 5000 litres for one kilogram of cheese, 70 litres for one apple and 50 litres for one orange.
Calculating a water footprint is very complex, and the Water Footprint Network is developing standards for water footprint accounting, impact assessment and offsets.
CSIRO is participating in this process, developing a methodology that takes into account whether water is provided by irrigation or natural rainfall, as the latter has a much lower footprint than irrigation.
This methodology will reduce the water footprint of grass-fed beef.
Currently the Water Footprint Network estimates it takes 15,500 litres of water to produce one kilogram of feedlot beef, the amount used in growing the food consumed by the animal over three years, together with its drinking water.
The Network is also looking at national water footprints.
Its current statistics show that Australian consumption accounts for 1393 cubic metres of water per person each year, 52pc of which is consumed in domestic agricultural produce.
The US population consumes almost twice as much water, 2483 cubic metres per head, 48pc of which is consumed in domestic agricultural produce.
Indonesia by contrast has an individual footprint of 1317 cubic metres, of which 87pc is consumed in domestic agricultural produce.
Chinas footprint is even smaller, 702 cubic metres, 80pc of which is consumed in its own produce.
Many countries depend on imported food, which means they are consuming other countries water.
For instance, imported food accounts for 47pc of the UKs water consumption and 53pc of Japans water consumption.
If you'd like to know more about water footprinting, visit the website of the Water Footprint Network, at www.waterfootprint.org.
