The Water in Our Food

water in our food

By Arjen Y. Hoekstra, University of Twente, the Netherlands

One single component in the total water footprint of humanity stands out: the water footprint related to food. About 85% of humanity’s water footprint is related to the consumption of agricultural products; 10% relates to industrial products and only 5% to domestic water consumption. Within the category of agricultural products, one sub-category stands out: animal products.

Products derived from animals generally have a much larger water footprint per kilogram or caloric value than crop products. This means that if people consider reducing their water footprint, they better critically look at their diet than at their water use in the kitchen, bathroom and garden. Wasting water never makes sense, so saving water at home when possible is certainly advisable, but when we would limit our actions to water reductions at home, many of the most severe water problems in the world would hardly be lessened. The water in the Murray-Darling basin in Australia [for example] is so scarce mostly because of water use for the production of various types of fruits, vegetables, cereals and cotton.

The Ogallala Aquifer in the American Midwest is gradually being depleted because of water abstractions for the irrigation of crops like maize and wheat. Much of the grains cultivated in the world are not for human consumption but for animals. In the United States, for example, 68% of the grains consumed is used for animal feed. Animal products do not have a relatively large water footprint because of the water volumes required for drinking, but because of the water needed to grow the feed. From a water-saving point of view, it is obviously more efficient to eat the crops directly then indirectly by having them first processed into meat.

Consumers can reduce their direct water footprint – i.e. their home water use – by installing water-saving toilets, applying a water-saving showerhead, etc. For reducing their indirect water footprint – that is the water consumption behind the production of food and other consumer products – they have basically two options.

One option is to substitute a consumer product that has a large water footprint by a different type of product that has a smaller water footprint. Eating less meat or becoming vegetarian is one example, but one can also think of drinking tea instead of coffee, or even better plain water. Not wearing cotton but synthetic fibre clothes also saves a lot of water. But this substitution approach has limitations, because many people do not easily shift from meat to vegetarian and people like their coffee and cotton.

A second option is that people stick to the same consumption pattern but select the beef, coffee or cotton that has a relatively low water footprint or that has its footprint in an area that does not have high water scarcity. This requires, however, that consumers have proper information to make that choice. Since this sort of information is generally not available, this in turn asks for an effort from businesses to create product transparency and an effort from governments to install the necessary regulations.

Currently we are far removed from a situation in which we have relevant information about the environmental impact of one piece of beef compared to another piece. The water footprint of beef, however, greatly varies across production systems and countries and strongly depends on feed composition. The same holds for other food items.

The water footprint concept is an analogue to the ecological and the carbon footprint, but indicates water use instead of land or fossil energy use. The water footprint of a product is the volume of freshwater used to produce the product, measured over the various steps of the production chain.

Water use is measured in terms of water volumes consumed (evaporated) or polluted. The water footprint shows volumes of water use and pollution, but also the locations, which is relevant, because the impact of water use depends on local conditions. A water footprint generally breaks down into three components: the blue, green and grey water footprint. The blue water footprint is the volume of freshwater that is evaporated from the global blue water resources (surface and ground water). The green water footprint is the volume of water evaporated from the global green water resources (rainwater stored in the soil). The grey water footprint is the volume of polluted water, which is quantified as the volume of water that is required to dilute pollutants to such an extent that the quality of the ambient water remains above agreed water quality standards.

Table 1 shows the global average water footprint for a number of common food products. The numbers show that, as expected, animal products are more water-intensive than food crops. However, what the averages hide is that there is a very large variation of the water footprint for each of the products shown in the table. Knowing these differences is essential if one has already chosen to buy a certain product but not yet chosen which of the various options that still remain. One piece of beef is simply not equal to the other one, even though the taste and all other measurable characteristics are the same. The history may be different.

Considering that so much of the water we consume/use can actually be attributed to the foods we eat, it would be an eco-friendly move to do even the smallest thing differently with regards our diet. Have a  “Meat Free Monday” and you will have made a huge global difference (for example)! Or simply, eat more consciously- as the Slow Food movement suggests. As the above article points out, a sweeping act of vegetarianism may not be the answer-  KNOWING where your food comes from and how it is produced (meat, grain or otherwise) may be of far greater value! You may wish to read Curious about Slow Food? by ecovitality, as well. Here you will find a few South African Slow Food contacts to help get you moving (slowly) in the right direction!

Article source:

, , , , ,