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5.1.6: Virtual Water

  • Page ID
    48210
  • How much water do you eat?

    Water is essential to growing food and every bite of food we consume required water to grow, process and transport. The water necessary to grow, process and transport food is often referred to as virtual water or embedded water. Virtual water is the entire amount of water required to produce all of the products we use, including our mobile phones and cotton t-shirts. But a global assessment of virtual water reveals that the majority of water that we consume is in the food we eat. If we total up all of the virtual water embedded in everything we use and eat, we can estimate our total water footprint. Water footprints can be used to provide insights into how much water is used every day in all of our activities including producing our food. For example, Figure 4.1.12 shows the amount of water used per person around the globe associated with wheat consumption. When you eat food imported from another region, you are eating the water of that region. The apple from New Zealand, grapes from Chile and lettuce from California all required water to grow and by consuming those products you’re "eating" that virtual water. The concepts of virtual water and water footprints can be powerful tools for businesses and governments to understand their water-related risks and for planning purposes (water footprint network).

    water footprint.png

    Figure 4.1.12.: Water footprint per capita related to consumption of wheat products in the period 1996–2005. Credit: Figure from Hoekstra, A.Y. and M.M. Mekonnen, 2012, The Water Footprint of Humanity, Proceedings of the National Academy of Sciences, vol. 109, no. 9

    Check Your Understanding

    Scroll through this infographic explaining virtual water and then answer the questions below.


    Check Your Understanding

    Scroll through this infographic explaining virtual water and then answer the questions below.

    Knowledge Check (MC)

    1) How many liters of water do you "eat" every day?

    • 6.4 quart

    • 3.2 gallons

    • 3.496 liters

    2) If there are 3.8 liters per gallon, how many 20-gallon aquariums is that?

    • 3,496 liters is 920 gallons, which is 46 20-gallon aquariums of water that each of us "eats" per day.

    • 3,496 liters is 1840 gallons, which is 92 20-gallon aquariums of water that each of us "eats" per day.

    • 3,496 liters is 460 gallons, which is 23 20-gallon aquariums of water that each of us "eats" per day.

    3) What percentage of the total water consumed on average per person per day is associated with the production of the food we consume?

    • 12% of the water we use is in our food

    • 62% of the water we use is in our food

    • 92% of the water we use is in our food

    4) How big would the wall of one-liter water bottles equivalent to 15,400 liters? Convert the size of the wall to feet. How big is it?

    • The wall of one-liter water bottles would be 2 meters by 10 meters, or about 6 feet by 33 feet.

    • The wall of one-liter water bottles would be 15 meters by 60 meters, or about 49 feet by 197 feet.

    • The wall of one-liter water bottles would be 8 meters by 40 meters, or about 26 feet by 131 feet.

    5) Based on the graph of the amount of water needed to produce different food products, what sort of diet would you conclude uses the least/most amount of water?

    • The graph shows that in general plants require less water to produce per kilogram than animal products, except for sugar.

    • The graph shows that in general plants require less water to produce per kilogram than animal products, except for coffee.

    • The graph shows that in general plants require less water to produce per kilogram than animal products, except for rice.

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