3813 views last update:6 Aug 2012

Virtual water not potable, but accountable?

Dick Ziggers
Researchers at the University Twente (UT), Enschede, the Netherlands, in a study quantified and mapped the water footprint (WF) of humanity at a high spatial resolution. The study introduced the topic of 'virtual water' in order to track gross and net trade in water. Unfortunately production of animal protein remains the highest consumer of this indispensible liquid, whatever name it is given to it.

Virtual water is the water used in products and commodities, for example the total amount of water involved in growing, harvesting, transporting, and milling grains.
Generally, one can distinguish three main water-using sectors: the agricultural sector, the industrial sector, and the domestic water supply sector. Adding up all calculations it appears that agricultural production contributes 92% to the water footprint of the world.
Consumption of cereal products gives the largest contribution to the WF of the average consumer (27%), followed by meat (22%) and milk products (7%).
If we take a closer look on a product level what would then be the water use of a hamburger or a glass of milk? Well, UT scientist just did that. They quantified the water footprint of a soy burger and of soy milk and compared the outcome with the WF of a beef burger and cow’s milk.
The water footprint of 1 l soy milk was calculated at 297 l, of which 99.7% refers to the supply chain. The water footprint of a 150 g soy burger is 158 l, of which 99.9% refers to the supply chain.
Companies nowadays next to their financial report often produce an environmental or sustainability report, which focuses on just their own operational performance. This water footprint study with the virtual water use coefficient study shows that it is important to consider the complete supply chain.
The major part of the total water footprint stems from ingredients that are based on agricultural products. In the case of soy milk, 62% of the total water footprint was due to the soybean content in the product; in the case of soy burger, this is 74%.
The shocking part is – and many of you may already have read these figures – that cow's milk and beef burger have much larger water footprints than their soy equivalents. The global average water footprint of a 150 g beef burger is 2,350 litres and the water footprint of 1 l of cow's milk is 1,050 litres.
I may kick a lot of environmentalists in the shins, but despite these alarming figures I still prefer real beef and milk above its soy equivalents.

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