LESSON SUMMARY
This activity introduces the concept of virtual water that is embedded water in our food. Students will
explore the implications of importing and exporting virtual water and will use a country’s water footprint
as a way to explain water self-sufficiency.
FOCUS QUESTION
How do our food choices affect our overall water consumption?
BACKGROUND
According to the Canadian Water Governance group, the water Canadians use for washing, cooking,
flushing the toilet and drinking add up to about 331 litres per day.1 Many of us don’t realize however,
that without thinking about it, we also consume hundreds of thousands of litres of water that is
embedded in our food, clothing and other products. This water use contributes to our overall water
consumption, or water footprint, and is called virtual water.
The concept of virtual water was first put forth by Professor John Anthony Allan as a means to quantify
the amount of water that is used in the production of a good or service.2 The Water Footprint Network
suggests that the water used in production is said to be ‘virtual’ because it is no longer contained in the
final product.
For example a standard microchip contains about 32 litres of virtual water, but this water is not
physically sitting in our computers. Virtual water takes into account the total amount of water used
throughout each step of production.3
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Accounting for virtual water becomes extremely important when we consider issues around food
production and distribution. While calculating the precise volume of virtual water in products is difficult,
the concept encourages us think about water differently – a few litres of water are wasted when you
take a long shower, but hundreds (or even thousands!) of litres of water are wasted when you throw
away food. Some common virtual water values are listed below.
Approximate Volume of Water Used
for Growing, Harvesting, Processing, etc.
1 glass of milk = 200 litres of water
1 orange = 50 litres of water
1 slice of bread = 40 litres of water
1 apple = 70 litres of water
1 glass of apple juice = 190 litres of water
1 bag of potato chips = 185 litres of water
1 glass of orange juice = 170 litres of water
1 hamburger = 2400 litres of water
1 egg = 135 litres of water
1 kilogram of beef = 15500 litres of water
1 cup of coffee = 140 litres of water
1 kilogram of chicken = 3900 litres of water
1 cup of tea = 30 litres of water
1 kilogram of goat meat = 4000 litres of water
1 potato = 25 litres of water
1 kilogram of soy beans = 1800 litres of water
1 tomato = 13 litres of water
1 kilogram of sugar = 1500 litres of water
From: www.waterfootprint.org
Measuring our “ecofootprint,” allows us to quantify our overall impact on the environment in terms of
how many hectares of land required to maintain our lifestyle. Recently, the concept of measuring our
“water footprint” has also become prevalent. The “water footprint” of a country, organization or person,
is defined as, “the total volume of freshwater that is used to produce the commodities, goods and
services consumed” by the country, company or person.4 In Canada, our water footprint is 204.9 m3
water/capita/year (or 204900 litres/person/year); significantly higher than most other countries around
the world.5
Tracking the volume of virtual water that is contained in the foods we produce, export, import, and
eat allows us to tackle water issues on local, national and global scales. It means that as a global
community, we can adjust our trading practices to allow areas with less water to gain access to foods
(and other products) with higher water requirements by importing them from areas with high rainfall
and increased access to water. The hope is that water-scarce regions can then in turn, export crops
that are less water intensive, thus requiring less water for domestic agriculture and allotting more water
resources for drinking and sanitation. UNESCO (United Nations Educational, Scientific and Cultural
Organization) estimates that we have already reduced our global use by 5% simply by managing virtual
water more efficiently.6
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TRACKING THE WATER ON YOUR PLATE
1. Have students complete PART ONE of “The Puddle on your Plate” question sheet and record
their answers individually.
2. In pairs, students should discuss their answers and select one of the food items (or one component of a food item) from their list that was imported to Canada from elsewhere
in the world.
4. Explain the concept of virtual water, by highlighting some examples of virtual water values in common foods and discussing virtual water management between nations based on food imports and exports. You can begin by showing the “A Comprehensive Introduction to Water Footprints” slideshow available from the Water Footprint Network at
www.waterfootprint.org/?page=files/TM_Presentations.
Ask students to consider the stages of production for the food item they have selected.
Where is water being used? How might virtual water be embedded into this item?
5. Ask students to then consider the national water footprint for the country that produces their selected food item. Logging onto the Water Footprint Network website at
http://www.waterfootprint.org/?page=cal/waterfootprintcalculator_national
will allow students to calculate the external water footprints of various countries. The water footprint of a nation refers to the total amount of water that is used to produce the goods and services consumed by the inhabitants of the nation. The total water footprint of a country includes two components: the part of the footprint that falls inside the country (internal water footprint) and the part of the footprint that is drawn from other countries in the world (external water footprint).7
Because Canadians import rice from India, the amount of virtual water contained in the rice is factored into the external portion of Canada’s national water footprint. Canada’s external water footprint represents 20% of our total national water footprint, meaning that we are a relatively water-rich country and 20% of the virtual water we consume is shipped to us in products
from other countries.
6. In pairs, ask students to discuss, investigate and research the questions outlined in PART TWO
of the “The Puddle on your Plate” worksheet and record their answers.
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7. Next, ask students to form groups of 4 or 5 and create a “Virtual Water Menu” that features the food items they selected and the water footprint information collected about the food’s country
of origin. Invite students to be creative in choosing the menu’s content, theme and layout.
The Virtual Water Menus could include:
- images, icons, symbols, graphs or other visual representations that symbolize
water content of the foods offered
- maps to show where the menu’s foods came from and where it travelled,
- the water footprint of the foods’ countries of origin,
- the water availability in those countries
- a variety of media.
EXTENSION QUESTIONS
Environmental issues are often presented within a “doom and gloom” context that can leave us feeling
overwhelmed and depressed. How would you share what you have learned about the connections that
link our food consumption and our water consumption in such a way that inspires and motivates others
to take action?
There is no global consensus on the importance of tracking virtual water as it moves from one country
to another? Why do you think some countries would oppose this type of measurement? How could
tracking virtual water imports and exports be problematic?
ASSESSMENT AND EVALUATION
4
3
2
1
Organization
Information in the menu
is very organized.
Information is organized.
Information is somewhat
organized, but it is
difficult to follow the flow
of the menu.
The information appears
to be disorganized.
Quality of
Information clearly
relates to the main
topic. It includes several
supporting details and/or
examples from a variety
of sources.
Information clearly
relates to the main
topic. It provides some
supporting details and/
or examples from some
sources.
Information clearly
relates to the main
topic. No details and/or
examples are given.
Information has little or
nothing to do with the
main topic.
Diagrams and
illustrations are neat,
accurate and add to the
reader’s understanding
of the topic.
Diagrams and
illustrations are accurate
and add to the reader’s
understanding of the
topic.
Diagrams and
illustrations are neat and
accurate and sometimes
add to the reader’s
understanding of the
topic.
Diagrams and
illustrations are not
accurate OR do not
add to the reader’s
understanding of the
topic.
The relationship
between the variables is
discussed and trends/
patterns logically
analyzed. Thoughtful
conclusions are drawn
based on the outcome
of the activity.
The relationship
between the variables is
discussed and trends/
patterns logically
analyzed. Superficial
conclusions are drawn
based on the outcome
of the activity.
The relationship between
the variables is discussed
but no patterns/trends
are identified.
The relationship
between the variables
is not discussed.
Information
Diagrams &
Illustrations
Discussion
Questions
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Action: Change within Yourself
Go meatless! Producing meat (especially beef) requires significantly more water than soy beans and
other crops. Limiting your consumption of meat will reduce your overall virtual water use. Be sure that
you reduce your meat consumption in a healthy way by supplementing your diet with other protein and
iron-rich foods such as tofu, spinach and broccoli.
Empty your plate! Sometimes our “eyes are bigger than our stomachs”, but throwing away food not only
wastes energy and natural resources but it can also be the equivalent of pouring thousands of litres of
water down the drain.
Action: Change within Your School
Increase Awareness! Host a school-wide screening of a water-themed documentary. A World without
Water is a fantastic video that can be downloaded for free online. Other great titles include Waterlife,
FLOW and Running Dry.
Support local food at school! Does your school or school board have a local food procurement policy?
Is it being implemented? If one doesn’t exist, what could be done to initiate the process?
Action: Change within Your Community
Support local farmers! When local food is in season, neighbourhood farmers’ markets are the best
places to buy groceries that haven’t travelled great distances to arrive on your plate. Most farmers’
markets are listed online and many even run year-round!
1
www.watergovernance.ca/factsheets/pdf/FS_Water_Use.pdf
2
waterfootprint.org
3
Ibid
4
www.traumkrieger.de/virtualwater/
5
Ibid.
6
waterfootprint.org
7
www.waterfootprint.org
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PART ONE
1. What did you have for dinner last night?
2. Which item of food was your favourite?
3. What is the country of origin of your favourite food item? Where was is produced? If you don’t know the answer to this, how could you find out?
4. What are some of the ingredients in your favourite food item?
5. Where did these ingredients originate?
Ingredient
Country of Origin
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PART TWO
1. What was the external water footprints of the countries you identified?
2. At first glance, would these countries be considered to be water-rich or water-scarce? Why?
3. Does the external water footprint of the countries you selected help to explain whether they are water-rich or water-scare? If so, how? If not, why?
4. What other factors (geographic, economical, social, environmental, etc.) might be involved in calculating a country’s external water footprint?
5. What are some ways that your selected countries could decrease their external water footprints while continuing to meet their water and virtual water needs?
6. How could these countries achieve water self-sufficiency? Is water self-sufficiency a realistic goal for these countries? Explain your rationale.
2010 © Toronto and Region Conservation, Permission to reproduce this page is granted for classroom use only.
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2010 © Toronto and Region Conservation, Permission to reproduce this page is granted for classroom use only.
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