Water Footprint – The Importance of `Virtual Water’

Water is one of our planet’s most precious resources. It is ubiquitous: we drink it, wash with it, swim in it, and sail on it. We also use it to produce things like food, paper, and cotton clothing, among others.

But what is “virtual water?” Is it invisible? Sort of. But it is equally – if not more – omnipresent.

Virtual water, or the water footprint, is an indicator of water usage that looks at both direct and indirect water use of a consumer or producer. The water footprint of an individual, community or business is defined as the total volume of fresh water used to produce the goods and services, consumed by the individual /community or produced by business.

We don’t realize it as we sit down to a meal, but most crops require huge volumes of water to grow: 65 gallons to grow a pound of potatoes; 650 gallons for a pound of rice. How about your cup of coffee? It takes far more than one 10 ounces to make it. Thirty-seven gallons of water were used from the time the bean was planted to the moment it hits your cup at Starbucks. That includes growing, harvesting, packaging, and shipping it. And that’s without adding any milk (which took another 67 gallons of water to produce).

At a national level, it becomes more complicated. Here’s the formula:

Domestic water resources used


virtual water exports


virtual water imports

equals: the water footprint of a nation

The total water footprint of a nation is an indicator of a nation’s demand for global water resources, and is tied to dietary habits of people. High consumption of meat brings along a large water footprint. Also, more the food that originates from irrigated land, larger the water footprint becomes.

Nations in warm climate zones have high water consumption for their domestic food production resulting in a larger water footprint. Increasingly, these countries are relying less on their own resources and are switching to food imports. Those imports include importing the water embodied in the crops, or virtual water.

So, every ton of wheat arriving in port brings along (in virtual form) the tons of water needed to grow it.

Two-thirds of all the water drawn from nature by humans is used to grow crops. Nearly one-tenth of the water used in growing crops is traded internationally. Exchanging virtual water – from grains and vegetable oil, sugar and cotton, meat and dairy products from animals raised on crops – has kept the world fed.

The virtual water trade is not a bad thing. It allows the world’s food to be grown where it makes the most sense. It improves efficiency in the production of vital foodstuffs like grain. But our growing reliance on it creates risks, because the trade can only go so far. It requires both exporters and importers and, as water shortages emerge around the world, exporters will be in short supply.

That all being said, we are not about to run out of water. Thanks to Mother Nature’s water cycle of rainfall and evaporation, water is the most renewable of all resources.

However, it is worth noting that humans are affecting that natural cycle on such a scale that some of the great rivers of the world are, indeed, running dry. And, if harvests fail because of dry river beds, it is little comfort to know that it’s raining somewhere else.

Article by Bari Faye Siegel, a technology writer and marketing consultant at Noveda Technologies, an innovative leader in real-time, web-based energy and water monitoring.

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2 comments on “Water Footprint – The Importance of `Virtual Water’


Oh, good lord! Are we going to these extremes now? Why not a Virtual Air study? Or a virtual Gazing At Trees study (how much does it impact the squirrels?)?

Here’s a virtual water study for ya – I just had six beers and 2 burritos, now i’m going to take a dump and flush about 3 times.

Please come and study this. Dumbasses…


To paraphrase the great Sam Kinison —



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