Compared to a vegan diet, eating meat, dairy and eggs uses a lot of water!

Studies carried out by researchers in Australia and overseas show that over 20 times more fresh water is required to produce animal products compared to the same weight of plant products. Animal agriculture puts a huge strain on our water resources and compromises our water security.

While directly saving water at home is a noble idea, most people don't realise that water used to produce our food makes up 90% of all water used by an average Australian household. So whether saving water for drinking, or saving our mighty rivers and their wetlands, moving to a vegan diet will have a much more positive impact than having shorter showers or not watering the garden.

As the graph above shows for Australia, producing 1kg of beef, lamb, pork and other animal products takes many more litres of water than 1kg of vegan foods, like grains, beans, fruit and vegetables.

Did you know?

• It takes over 20 times more water to produce 1kg of beef compared to rice, grains, beans, fruit and vegetables in Australia.
• It takes 800 litres of water to produce one litre of cow's milk, four times as much as it takes to make one litre of soy milk.
• Vegan households use less than a third of the water of the average Australian household.
• Agriculture is the number-one user of water, accounting for 65% of total water consumed in Australia and 70% worldwide.
• Animal agriculture is responsible for up to one third of all fresh water consumption in the world today.
• 43% of irrigation water in Australia is used by the animal agriculture industry.
• Only 24% of irrigation water in Australia is used for fruit, vegetables and grains for human consumption.
• The dairy industry uses 19% of irrigated water in Australia and is responsible for 35 per cent of water consumption in the Murray-Darling basin, Australia's most important agricultural region.
• The world will run out of fresh water by 2050 if we continue to consume animal products at the current rate, according to the Stockholm International Water Institute.

The research behind the numbers

The values used to create this graph come from a 2010 study by researchers at the UNESCO Institute for Water Education. The values for animal products are for Australia. Unfortunately the study does not show the values for plant products for Australia, so global average values are displayed. However, according to earlier work (2005) by the same researchers, water use for plant production in Australia is about the same as or less than the global averages.

The graph above was derived from research done by the UNESCO Institute for Water Education. Other researchers have found even greater discrepancy between animal and plant foods. Earlier research by CSIRO in Australia estimated that it takes 50,000 litres of water to produce 1kg of beef, but only 1,010 litres to produce 1kg of wheat, 2,200 for soybeans and 2,385 for rice.

All values discussed so far have been litres per kilogram. Because different foods have different energy densities, another useful measure is the number of litres of water used to produce one calorie or megajoule. This would account for the fact that there is more energy in a kilogram of tofu than in a kilogram of broccoli. However, even using this measure, animal products are still very water intensive, with beef using about 10 times more water than most fruits and vegetables. Research by CSIRO shows that fruits and vegetables generally require around 200 litres of water per megajoule, whereas beef requires 2,500 litres per megajoule. Similar figures are obtained when protein is measured rather than energy, with research published in The American Journal of Clinical Nutrition stating that "producing 1 kg of animal protein requires about 100 times more water than producing 1 kg of grain protein."

As shown above, there is some difference between the numbers found by various researchers, but, as one researcher has noted, "All authors agree the water footprint of beef is [...] much larger than the water footprint of grains."

Values used for graph

Sources for figures used: Animals (Table 4), Crops (Table 4)

The values used for lentils, chickpeas, rice and pasta have been adjusted by the factors given to take into account their increase in weight when cooked.

Links

• Water Footprint Network
• The green, blue and grey water footprint of crops and derived crop products, M.M. Mekonnen, A.Y. Hoekstra
• Water footprint of crop and animal products: a comparison, Water Footprint Network
• The water in our food, Paul Mahony
• Water footprints of nations: Water use by people as a function of their consumption pattern, A. Y. Hoekstra, A. K. Chapagain
• Water for Food - the continuing debate, Wayne Meyer
• Sustainability of meat-based and plant-based diets and the environment, David Pimentel, Marcia Pimentel
• Comments on Meat & Livestock Australia's "myth busters" and other claims, Paul Mahony
• Water Account, Australia, Australian Bureau of Statistics
• Demand for Meat Is Driving Water Shortages Affecting 4 Billion People

(This article originally appeared in the March 2019 issue of The Australian Vegan Magazine).