Session 1: Earth’s Precious Water

Why Is Water Precious?
Water is precious because life could not exist without it. Life was born as a result of water, from plants to animals to humans. Despite Earth’s appearance of watery abundance, less than one percent of the water on Earth is actually fresh and usable. Nature’s water-recycling process, known as the water cycle, has kept the amount of water on Earth about the same for millions of years.

Try This!  

1 Life Needs Water to Live
2 Looks Can Be Deceiving!
3 Recycled Water Cycle
4 Quiz Yourself




1 Life Needs Water To Live Top

Read to Learn
All living things depend on water for survival. Plants need water to make food and grow. Many animals and plants live in water. People need water for cooking, bathing, transportation, recreation, and for growing crops and making products. Without water, there would be no food to eat, no clothes to wear, and no toys to play with. In fact, our bodies are all made of water. Without water, we wouldn’t exist!

Do to Learn: Classroom
Did you know that your body is 70 percent water? That means a person who weighs 100 pounds (45 kilograms) is made of 70 pounds (32 kilograms) of water! That’s almost 8.5 gallons (32 liters). You can figure out how much water you are made of by weighing yourself and then multiplying your weight by 0.7.

Weigh yourself and calculate how much of your weight is water. Add up the water-weights of everyone in your class. How much water is your class made of?


2 Looks Can Be Deceiving! Top

Read to Learn
Do you believe water is abundant and never ending? Looks can be deceiving; only one percent of all of the water on Earth is fresh, liquid, and usable! Earth, sometimes known as the blue planet, is covered by more than 75 percent water-salt water. Another two percent is frozen.


Breakdown of Earth's water


Imagine 26 one-gallon jugs (50 two-liter bottles) filled with water. These jugs represent all of Earth’s waters. The amount of usable fresh water would only be enough to fill one 12-ounce (354-milliliter) soda can!

Do to Learn: Computer Lab
Check out this link for detailed information about the amount of fresh water on Earth.

Read to Learn
How much water do you think is used every day in the U.S.?

PEOPLE: We need to drink about 0.5 gallon (2 liters or 8 glasses) of water each day. Two more gallons (8 liters) are used for drinking and cooking. A person can live one month without food, but only one week without water.

HOMES: Each person in the United States uses about 90 gallons (341 liters) of water a day for cleaning and gardening.

FACTORIES: Factories use enormous amounts of water to produce goods. It takes 60,000 gallons (227,000 L) of water to make a ton of steel.

FARMS: Farms use water to irrigate land for growing crops and to raise livestock. It takes 115 gallons (435 liters) to grow the wheat for one loaf of bread, and 4,000 gallons (15,000 liters) to produce one pound of beef.

The table below shows how much water it takes to make some common things:
Item Water Used
A small car 120,000 liters 450,000 gallons
A ton of plastic 37,000 liters 140,000 gallons
A ton of paper 14,000 liters 54,000 gallons
A bag of cement 47 liters 180 gallons
A bicycle 34 liters 130 gallons
A wool sweater 26 liters 100 gallons
Four gallons (1 liter) of gasoline 18 liters 70 gallons
Two pounds (1 kilogram) of instant coffee 15 liters 55 gallons
A pair of leather shoes 14 liters 53 gallons
A newspaper 2 liters 9 gallons
A small bar of chocolate .3 liter 1 gallon

Do to Learn: Classroom and Home
Keep a log of how much water you use in one day.

PART 1: Using a lined notebook, write down every time you use water for 24 hours and how much you use each time. (*See the chart below so you have an idea of how much of water used for daily routines.)

PART 2: Using the information from this log, imagine you are going to the desert for a week. Estimate how much water you will need to take with you to survive. Do you need to bring all the water you plan on using, or will you be able to find water in the desert to use? Hint: The Saguaro cactus a great deal of water in its body. Can you think of other ways to conserve water? How about skipping baths?!

*Water Chart: Use these numbers to help you estimate how much water you use for daily activities:
Activity Water Used
Have a drink .13 gallon .5 liter
Wash your hands and face 2 gallons 9 liters
Brush your teeth .26 gallons 1 liter
Take a bath 24 gallons 90 liters
Take a shower 7 gallons 27 liters
Flush the toilet 2 gallons 9 liters
Wash a load of laundry 31 gallons 118 liters
Water the garden 2 gallons 9 liters


3 Recycled Water Cycle Top

Read to Learn
Earth’s water is used over and over again. The water you use daily is older than the dinosaurs! The first water that appeared on Earth is all we will ever have. The water cycle is also known as the hydrologic cycle. Both refer to the natural phenomenon of water recycling.

Look to Learn: Computer Lab
Here’s a detailed look at how the water cycle works:


image: the water cycle
Illustration by John M. Evans USGS WRD Colorado District


Read to Learn
Heat energy from the sun drives the water cycle. Heat makes liquid water change to vapor. This process is called evaporation. As the water vapor rises into the air, it cools. At cooler temperatures, water vapor condenses into liquid droplets that form clouds. Clouds can move water over long distances.

Eventually, the fresh water falls to the Earth as rain, sleet, hail, or snow. All forms of water that fall from the atmosphere are called precipitation. Some of this water soaks deep into the ground and becomes groundwater. Some runs down hills and mountains into rivers and lakes. This water is called runoff.

Eventually, both runoff and much of the groundwater flow into the oceans. At the surfaces of the oceans and the land, the sun warms the land and the surface waters, and the water on earth turns into a vapor (gas) again. It then returns to the atmosphere and the cycle starts over again.

Do to Learn: Classroom
Imagine that you are a drop of water.
Write a first-person narrative describing the changes you will experience as you move through the water cycle. Here are a few ideas to help your story ‘move’:

  • What will you do while in each part of the cycle?
  • What caused you to change into a vapor and then into rain?
  • What will you see on your journey?
  • How will plants and animals make use of you?


4 Quiz Yourself Top

Look to Learn: Computer Lab
Take a quiz to see how much you know about the properties of water.


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