We try to conserve water, we think that we’re helping the environment – and miss the heart of the water problem: In Germany, we indirectly use 4000 liters of water per day and person indirectly, through the food we consume and the products we use. Our indirect water use thus far outweighs the 120 liters of drinking water that each of us uses on a daily average.
Media outlets have recently picked up this phenomenon – also known as “virtual water”. Usually, the general public is surprised about the huge amount of water that goes into the production of everyday amenities.
What most people don’t realize is that the total quantity of virtual water is less important than we might think. Advocates often quote the statistical fact that the production of a cup of coffee requires the use of 120 liters of water. Indeed, coffee is an example for a product with a large water footprint – but coffee beans are traditionally farmed in regions where rainfall is high and no artificial irrigation is required. Yet our calculations typically include the evaporating rain. On a global average, this yields a figure of 21,000 liters of water per kilogram coffee.
A different picture emerges when we consider the example of Spanish tomatoes. Tomato plants require an annual rainfall of around 330 liters per square meter to grow properly. In a region where annual rainfall totals 200 liters, tomato farming can hardly be sustainable and only becomes possible with intensive irrigation. To water the plants, farmers draw on non-renewable water resources. The consequences are dried-up swamps and increasing salt levels in the groundwater (which render it useless as a source of drinking water).
Assessing one’s personal behavior is more difficult in the context of virtual water than in the context of climate change. Less carbon dioxide is always a good thing – but reducing the size of one’s water footprint does not necessarily imply a sustainable lifestyle. The goal is to avoid the depletion of non-renewable water resources.
A few simple rules can serve as guidance: In most countries, locally grown fruit and vegetables are a safe bet. Organic local products are even better, since their production does not involve the use of pesticides and chemical fertilizer that might pollute the groundwater.
Another possibility it to limit meat consumption. Eating only one steak less per year conserves more water than switching one’s household supply from tab water to rain water. The production of one kilogram of beef requires the use of 15,000 liters of water – a kilogram of wheat requires less than a tenth of that. Conventional cattle farming also relies on high-energy fodder that is based on soy beans. In Brazil, the rain forest is under massive attack as large areas are cleared to make space for soy farming. Here, ecological farming has an advantage: It aims to maintain a closed production cycle and uses fodder that has been locally grown.
What is to be done? We need conscious consumers who pay attention to the origins of the products they buy, to the farming conditions and the ecological and social consequences of their production. That is where the concepts of virtual water and water footprints are most useful: They allow us to critically examine our consumption patterns and support the development of strategies that aim at a sustainable use of our water resources.