1. VIRTUAL WATER

2. Virtual Water: Context
The world’s population is set to go from 7 billion to 9 billion by 2050.
Evidence suggests that the more developed a nation, the more its people will eat a high-protein meat-rich diet.
As a result of both these factors, the UN Food and Agriculture Organisation predicts as much as 70% more food will be needed by the middle of the century.
In the developing world this could be as high as 100%.
Source: Smith. T (2012) World Water Day: How much water do you use in a day? At Accessed (link not available at time of resource review, April 2018)

3. Activity 1 Virtual water in food
Big idea:
Water is used in many ways to produce food and other items
Prior learning: water cycle; how to divide by 10, 100 and 1000; children to have possibly completed the globe and dinosaur activity.
An understanding of the word ‘virtual’ meaning that it is there but we can’t see it.

4. Resources needed:
One copy of ‘virtual water food’ worksheet per child: not included, this would need to be created – see source information on slides 8-14
Plastic, real or pictures of food items on ‘virtual water food’ worksheet with a sticky label attached indicating the answer e.g. glass of milk would have a sticky label with ‘200 litres’ written:
Interactive White Board to show film clips.
(Most of the data in this activity is extracted from ‘Virtual Water’ by Tony
Allan, an excellent guide to virtual water and problems associated with this). ISBN-13: 

5. Activity 1 outline:
Prior to the children entering, hide the items of food around
the classroom/playground area.
Children work in pairs to find the items on the worksheet
and complete the sheet with how many litres of water each item needs in order to be produced.

6. Watch the ‘all you eat’ video clip which explains how water is used to produce food:
(Background perspective on virtual water in food)
(Note: Scroll down to activate the animation on the webpage)

7. Here are some calculations of the water cost of different foods
as published in different websites…..

10. Cereal, 1 cup = 130 litres Orange Juice, 1 cup =170 L Coffee, 1 cup = 140 L Cheese, 1 portion = 250 L Rice, 100 g = 140 L Milk, 1 glass = 200 L Tea, 1 cup = 35 L Sugar, 1 piece = 10.5 L Lettuce, 1 kg = 130 L Apple/Pear, 1, 70= L Chicken meat, 150 g = 615 L Pork meat, 150 g, 690 L Egg, 1, 135 L Banana, 1, 70 L Olives, 100 g = 250 L Oats, 100g = 237 L Onions, 100g = 17 L Soybeans, 100g, = 275 L Pineapple, 100g = 42 L Chocolate, 100g = 2,400 L Cucumber, 100 g = 24 L Grapes, 100 g = 45.5 L Lemon, 100 g = 34 L Margarita Pizza = 1,216 L Hamburger = 2,400 L

11. Everything we eat is flooded with “virtual water,” or water used indirectly to produce food. In fact, 70% of the world’s water consumption feeds the agriculture industry, and demand for fresh water is increasing at a rate of one trillion litres a year. The GRACE Communications Foundation wants people thinking more critically about the water in their food, and has released a report that includes the average global water footprints for some of our most beloved—and resource-hogging—foods.
1. Slice of pizza = 42 gallons of water
That would be 18 gallons for the flour, 21 gallons for the cheese, and nearly 3 for the sauce. Mozzarella, it turns out, is a real water suck, as is any animal product. Of course, this is the global average, and water use per slice varies from country to country. French pizza has less than half this footprint, the US just about hits the average mark, and Chinese pizza is slightly more waterlogged.
2. A dozen eggs = 636 gallons
That’s right, every single egg requires an average of 53 gallons of water to produce. Chickens require water-intensive grain feed (about two pounds per every pound of chicken protein produced) as well as water for drinking and irrigation.
3. A pound of lettuce = 30 gallons
In general, vegetables take much less water to produce than animal products: That’s why GRACE’s report suggests “Meatless Mondays” as a step to conserve water—you don’t need to go vegan, but every bit helps. Even better news for salad lovers in the US: Lettuce’s footprint is less than half the global average there.
4. A loaf of bread = 288 gallons
Wheat is big. Between 1996 and 2005, global wheat production contributed 15% to the total water footprint of all crops. Make that sandwich open-face.
5. A bar of chocolate = 317 gallons
The report actually calculated the water footprint of a pound of chocolate, but that’s probably more than you eat in a sitting. Or a week, hopefully. But with one pound touting 3,170 gallons of water and a classic Hershey bar weighing 1.55 oz, or about 0.1 lbs, a single candy bar is still pretty wet. Say it ain’t so. You can find more water footprints here, though they’re calculated in litres per kilogram.

15. Understand that we consume vast amounts of water that we cannot see.
Activity 2
Virtual Breakfast
Big idea:
Understand that we consume vast amounts of
water that we cannot see.
Prior learning: virtual water in food activity

16. Activity 2 outline:
Ask the children to write what they would have for a typical breakfast.
Model how you would work out the amount of virtual water in your typical breakfast e.g.
1 slice of toast
1 cup of tea
1 bowl of cereal and milk

17. Slice of toast = 60 litres
1 cup of tea = 30 litres
I bowl of cereal (we do not have the data for this but we know it contains wheat, wheat = 500 litres for 500grams, an average bowl of cereal is about 30 grams) = 30 litres of water
Milk in the cereal (200ml glass is 200 litres of water so 100ml in cereal is 200 divided in 2) = 100 litres
So the total is……

18. ….60 + 30 + 30 + 100 = 220 litres of water consumed in my breakfast!
And that is just breakfast!

19. Children work together to work out how much
virtual water they have consumed in their breakfast….
Children then compare with other children on their table….

20. Breakfast, Lunch and Dinner…?
Breakfast: Cereal, milk, tea/coffee, orange juice…egg and bacon?
Lunch: Cheese and tomato sandwich, packet of crisps, an apple?
Dinner: Burger, chicken, beef steak, rice, pasta, vegetables?

21. 130L
200L
80L
600L
Tea: 35L
Coffee: 140L
170L
GRAND TOTAL =

22. Cheese: 250L
Bread: 40L
1 Tomato: 13L
LUNCH
70L
185L

23. For a lunch another 558 litres of water could be used
For a lunch another 558 litres of water could be used. By selecting a cheese and tomato sandwich (250 litres for the cheese portion, 40 litres per slice of bread and 13 litres for one tomato) your water footprint is already 303 litres.
Then if you wanted an apple (70 litres) and a bag of crisps (185) to go along with that you footprint would be higher.
Once again another cup of tea or glass of juice would further add to your day’s water footprint.

24. For dinner if you were to go for a margarita pizza for example, you could see a footprint of around 1216 litres, or if you wanted a burger, that would be 2400 litres of water.
Meat could see your footprint vary from 614 litres (100g of chicken meat) to 7000 litres (a beef steak).
A portion of rice would be 140 litres, while a pasta choice would be 130 litres while adding vegetables to your meal could add another 10.5 litres.

25. 2400L
7000L
614L
140L
130L
10.5L

26. M&Ms: 1153L
If you wanted some chocolate later in the evening, you would add 2400 litres to your footprint for 100g. And if adults wanted an evening drink, a glass of beer would be around 75 litres and a glass of wine could be 120 litres.

27. Water Footprint calculator

28. Teachers’ Notes – Follow-up Activities and Questions
As a follow up to this activity, children could work out how much virtual water they consume in a whole day.
Furthermore, if you have a link school in another country, you could ask them to do the same and compare the data:
Why is it very similar/different?
What types of food contains more virtual water?
How are the children’s diets similar/ different?
Does processed food contain more virtual water?
Why?
How could the children reduce the amount of virtual water they consume?

29. References
Allen. A (2011) Virtual Water: Tackling the Threat to Our Planet's Most Precious Resource, London. I.B Tauris
Mekonnen, MM and Hoekstra, AY (2011) National water Footprints Accounts: The Blue, Green and Grey water Footprint of production and consumption, Volume 1: Main Report. Value of water: Research Series No. 50. UNESCO- IHE Institute for Water
The Guardian newspaper Wednesday March
(though not available at time of resource review, April 2018)