Have you heard on average vegetarians use much less water than those who consume meat? Or drinking tea saves almost 90% of water when compared to a cup of coffee. Also, if you stop washing your jeans until you’ve worn them 10 times between washes you’ll reduce energy and climate impact by 80%.
These statistics might sound like hyperbole but they’re actually based on the concept of virtual water, a term coined by Prof. Tony Allan which puts a much more inclusive cost impact on how much water is needed to produce the goods we use and the foods we eat. This includes the grains grown specifically for cattle feed, water used to maintain facilities for livestock, and all of the rest of the litres per kilo of water related to producing American dietary staples like coffee, beef, pork, and cheese.
During our state’s severe drought here in California, most of us have become aware of another similar concept: water footprint. This figure accounts for the actual fresh water consumed to produce food or other commodities during the complete cycle.
Statistics shows that one person uses about 137 litres of water for domestic purposes, including showers, flushing toilets, cooking/drinking, and cleaning around the house. When factoring in the cost of industrial manufactured products we all use like clothing and paper, another 167 litres of water is accounted per person. However, these two figures only account for 10% of the total amount of water used by a person when factoring in virtual water use. We’re talking about as high as 3,496 litres for every person, per day!
A figure often cited is that agricultural needs far exceeds city water usage (40% vs. 10%). But perhaps it’s more useful to consider these percentages more thoroughly with the whole life cycle of product production in mind. Everything we see in supermarket aisles, on restaurant menus, or even at home might contribute to actual water consumption in much larger numbers than apparent.
For example, a grande size coffee in the morning needs 26 gram of roasted coffee. To grow a coffee plant and process the bean, the cost is 491 litres of water. However, a cup of black tea of the same size only requires 51 litres of water from start to finish.
In some ways – despite the severity of the drought – the local food culture or our water-dependent lifestyle here in California hasn’t changed much. But if we raise public awareness about the concept of virtual water and these invisible resource costs in producing all of our foods, perhaps we’ll not only conserve how much water we use around the house, but also the foods we put on our table.