How to save the world by eating veggies
We may not be able to transform the whole world just by eating our greens, but we can help to combat the water crisis, inter alia, by watching our water footprint.
And while many of us may already turn off the faucet while brushing our teeth or shower for five instead of ten minutes, a very large part of our water footprint is “hidden” in the clothes, energy and food we buy.
Water footprint – What?
“The water footprint is a measure of humanity’s appropriation of fresh water in volumes of water consumed and/or polluted.” (Water Footprint Network).
However, measuring humanity’s appropriation of fresh water poses quite a difficult task. How do we define fresh water? Does rainwater count? What about the water we pollute? In order to clear things up, the water footprint has been divided into a blue, green and grey one.
The blue water footprint is the amount of surface water and groundwater evaporated, incorporated into a product or placed somewhere else. Irrigation for instance has a blue water footprint.
With the green water footprint, the amount of water from precipitation (primarily rainfall) evaporated, transpired or incorporated by plants, is described. Agricultural products have a green water footprint.
The grey water footprint is the amount of fresh water required to assimilate the load of pollutants to meet specific water quality standards.
Since we cannot see the water incorporated into the products we buy, we call it virtual water. Ecologically speaking, it’s best if a product’s water footprint is composed of more green than blue water, since the latter is extracted from surface and groundwater resources and therefore taken from the natural hydrologic cycle (A. Sonnenberg, A. Chapagain, M. Geiger, D. August (2009). Der Wasser-Fußabdruck Deutschlands. WWF Deutschland).
Composition of the German Water Footprint
An average German consumes 5288 liters of water a day, of which only 178 liters are ascribed to daily life. 1205 liters are consumed through industrial goods, and a whopping 3904 liters are consumed in the form of agricultural goods (A. Sonnenberg, A. Chapagain, M. Geiger, D. August (2009). Der Wasser-Fußabdruck Deutschlands. WWF Deutschland).
By the way, Germany leaves around 70% of its water footprint outside of the country (Mekonnen & Hoekstra (2011) National Water Footprint Accounts, UNESCO-IHE) – through imported products.
Since food makes up such a big part of our water footprint, the water footprint depends a lot on the diet we follow. So how exactly does a water footprint-friendly diet look like? How can we, as consumers, save as much water as possible?
Let’s begin by examining the most water-intensive food products – chocolate (17196 liter/kg) and beef take the lead here. Depending on the country of origin, between 6400 and 19500 liters of water are needed to produce 1 kg of beef. This amount is so huge for various reasons, among others because everything the animals get fed has a water footprint of its own. Butter (5553 liter/kg), chicken (4325 liter/kg) and cheese (3178 liter/kg) also have a very large water footprint (numbers from Water Footprint Network, 2012). Note that apart from chocolate, all these are animal products.
When looking at the foods with the lowest water footprint, (surprise, surprise) we only find foods of vegetable origin. Tomatoes for example “only” have a water footprint of 214 liter/kg. Lettuce (237 liter/kg), potatoes (287 liter/kg), cucumber (353 liter/kg), bananas (790 liter/kg) and apples (822 liter/kg) are also relatively water-saving (numbers from Water Footprint Network, 2012). Anyhow, fruits and vegetables on their own do not make up a diet.
As is well known, it needs healthy fats, carbs, and protein. Oil crops (2364 liter/kg) and pulses (4055 liter/kg) both have a fairly high water footprint in liter/kg. Interestingly though, if viewed in liter/kilocalorie, their water footprint is still much smaller than that of most animal products. Nuts (3,63 liter/kilocalorie) are one of the very few exceptions of crop products which require more water than many animal products. Nonetheless, beef still surpasses all with 10,19 liter/kilocarorie (numbers from Mekonnen and Hoekstra, 2010).
The resource-efficiency of crop products compared to animal products becomes even more apparent when regarding the water footprint per gram of protein: Milk, eggs, and chicken need about 1,5 times more water than pulses. Beef needs almost 6 times more (Mekonnen and Hoekstra, 2010).
What does this mean? In the western countries of Europe, including Germany, a healthy, meat-reduced diet could reduce our water footprint by 26%, compared to our current diet. If we would entirely substitute the meat within that healthy diet for vegetarian sources of protein (e.g. pulses and nuts), it could reduce our water footprint by 41% ( Vanham, D., Hoekstra, A. Y. & Bidoglio, G. (2013). Potential water saving through changes in European diets. Environment International.).
Résumé: Saving water in daily life is great. The food we eat, however, has an even bigger impact on our water footprint. Buying less meat and more regional and seasonal vegetables enables us, as consumers, to reduce it. And by doing so – we help to save the world by conserving its most precious natural resource: water. Of course, we could portray the government and food industry as the villains, and maybe we should, but after all, it’s a system of supply and demand.