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O'Sullivan's Cascade
O’Sullivan’s Cascade, Ireland
Photograph by Richard Cummins/CORBIS
Wanted: Water!

“Wanted: Water!”

Your Mission

Be a Hydro-Hero!

Everyone everywhere must have fresh water. But does everyone everywhere have enough water? And is that water clean? The world is full of living things that depend on water—humans and hippos, hawks and hydrangeas, to name but a few. So the planet needs hydro-heroes (“hydro” means water) to make sure all people and other living things have clean, fresh water for a long, long time!

The Blue Planet: Water, Water Everywhere

Earth is called the “watery planet.” If you were an astronaut looking down at Earth from space, our planet would look mostly blue. Everywhere you look there’s water! It cleans sidewalks, overflows in fountains, glints in swimming pools, and gushes from taps and showerheads. It seems as though water is the most plentiful and least valuable resource around. From Earth’s outward appearance, it seems that everyone everywhere should have as much water as they need.

To help you “catch” on to how much of the Earth is water, your teacher is going to toss a lightweight globe to you and see how many times your index finger lands on water.

All the Water in the World

Much of the Earth is water, but there’s a “catch.” People need a certain kind of water for drinking and other basic activities, such as cooking, washing dishes, brushing their teeth, and flushing toilets.

You’re going to work in a group to learn how much of Earth’s water is available for people to use. Your teacher will give your group a container of water, a teaspoon or other measuring device, and three cups.

  • Cup 1 will represent “All the Water in the World.”

  • Cup 2 will represent “All the Fresh Water in the World.”

  • Cup 3 will represent “Fresh Water People Can Use.”

  • Step 1: Taking turns within your group, spoon 100 teaspoons (0.49 liters) of water from the big container into Cup 1. Cup 1 now represents “All the Water in the World.” Where in the world could you find that water? As a group, write down your answer. Some of that water is salt water. Some is fresh water. Can you “fathom” how much water is salty and how much is fresh? As a group, write down your answer.

    All the Fresh Water in the World

    Step 2: Remove 3 teaspoons (15 milliliters) of water from Cup 1 and put it into Cup 2. The water in one of the cups represents the amount of the kind of water you can’t drink and the water in the other cup represents the kind you can. Notice much of a difference between the two cups? When you find out which cup represents the water suitable for drinking, write down your response as a group.

    All the Water in the World That People Can Use

    There’s not much of the kind of water people need, is there? And we can’t even use all of this small amount of water. (Much of it is hidden or frozen.) How much of the world’s water does your group think people can use? Write down your answer as a group.

    Step 3: Pour all the water in Cup 1 into Cup 2. Cup 2 still represents all the world’s fresh water, but the ratio of water has changed. Add some blue food coloring to Cup 2 to help you remember that it represents fresh water.

    Step 4: In your group, take turns spooning 23 teaspoons (113 milliliters) out of Cup 2 and putting them into Cup 3. One of the cups represents fresh water that people can’t use. One cup represents fresh water people can use. When your groups finds out which cup is which, write down your response.

    People can use the water in lakes and rivers. There’s also water underground called groundwater. What proportion of the water that people can use does your group think is in rivers and lakes, and what proportion is in groundwater? As a group, write down your answer.

    Do you think the saying “What you see is what you get!” works for fresh water? How about the expression “out of sight!”? As a group, write down your answer. Choose someone from your group to tell the class your group’s thoughts during this activity.

    Wanted: Clean Fresh Water

    Water is a limited and precious resource. In North America, people use more of it per person than anywhere else in the world. In some countries, clean, fresh water is scarce. Some people have to walk for hours every day just to get a few gallons of water for basic necessities!

    With only a limited amount of water available, it’s important to keep fresh water clean. The pollution of fresh water can result from fertilizers, pesticides, litter (debris), oil, detergents, soot, animal wastes, sand, salt, and chemicals. Polluted water isn’t safe to drink, and it’s expensive to restore it to cleanliness.

    Join the Hydro-Heroes!

    You don’t need to fly or wear a cape to be a Hydro-Hero! You can be a hero to water just by doing ordinary things, like using less water when you wash the dishes and not throwing trash into storm drains. To keep the planet healthy for the future, we need to keep water as clean as possible. We should do our best to make sure everyone everywhere has enough fresh water. Here are a few things you can do:

  • Plan a “water conservation day” at home with your family. Talk with your family about different ways all of you could conserve water. Write these ideas down and practice them for a week. After a week, have a family meeting. Do you think you were successful? Then try to make your new water conservation practices a habit!

  • Get water-saving tips from Buster Backflow and Mr. Leakey at the Sacramento Area Water Works Association (

  • Find more water conservation tips at the American Water Works Association (

  • Join the Global Water Sampling Project. Work with other students online at their Web site to test fresh water around the globe (!

  • Go to Blue Mountain Greeting Cards ( and send an “Earth Friendly” greeting card to encourage water conservation!

  • Partially adapted from an activity by Jeff Cenoz, teacher-consultant, and “Learning with Otis” from the Missouri Department of Conservation in Jefferson City, Missouri. Also adapted from the 1993 Geography Awareness Week teacher’s handbook. Copyright © 1993 National Geographic Society.


    © 2000 National Geographic Society. All rights reserved.

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