With water restrictions looming yet again, the question has to be asked - what is the food industry doing about this scarce and precious resource. Well firstly - do you know how much you are using and how much you are wasting in your process? This article helps us to understand the volumes we work with.
What is virtual water?
The virtual-water content of a product is the volume of water used to produce the product in various steps of the production chain. The real water content is negligible compared with the virtual water content.
It, for example, takes between 410 and 1,700 litres of water to produce one kilogram of maize, and between11,000 and 21,000 litres of water to produce a kilogram of beef. For some other commodities see the table below. Of course, it is not just agricultural products and foods that can be measured in this way, any product has a virtual water content. One litre of biofuel requires 9,000 litres of water for its production. Further, it requires 1 litre of water to provide 1kcal (4.2kJ) of energy from a vegetable diet, and 10 litres for 1kcal from a meat diet.
What about water recovery?
The water may of course be recoverable. The water used may be considered as so-called green water which is the rain water that evaporates during production of the product, blue water which is ground water that evaporates during production of the product, and grey water which is water that is polluted during production of the product. The evaporation might be recovered in the form of rain and the polluted water might be purified for re-use. This obviously comes at a cost however.
Implications for the food and beverage industry
The implications are large because 70% of all the water used worldwide is for the production of foods. We live in a world where 900 million people do not have access to safe drinking water, where excessive use of ground water is leading to diminished reserves, and where climate change is contributing to drought in some parts of the world. So, a country which exports a million tons of maize is exporting 90m cubic metres of water. Conversely, the country that imports 1m tons of maize is importing 90m cubic metres of water.
A second aspect of the virtual water calculation that becomes important is the question of diet. Beef has a higher level of virtual water per kilogram than almost any other foodstuff. Saving of water may indicate the need for a change to other meats or to a vegetarian diet. There are now “eco-vegetarians”, those people who are willing to change to a non-meat diet in order to “save the planet”.
The concept of virtual water has its uses, but it also has limitations - it assumes that all sources of water are equal in value; it assumes that other uses will be found for the water saved by not producing the crop, and it does not put a value on pollution.
Regardless of the controversy, food producers should be doing everything possible to save water.
Editor's note
Why not share your story with us on how you are saving water in your facility? Just post your story in our FOOD FORUM and we will respond A.S.A.P.
Author
Andrew Murray of Andrew Murray Consulting
Email: andrew@gmail.com
