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21.3: Protecting the Water Supply

Difficulty Level: At Grade Created by: CK-12
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Lesson 21.3: True or False

Name___________________ Class______________ Date________

Write true if the statement is true or false if the statement is false.

_____ 1. A burning river helped people realize the need to protect water.

_____ 2. Water pollution has been reduced by laws fining polluters.

_____ 3. Most water pollution is caused by recreation on the water.

_____ 4. Coagulation is used during water treatment to remove chemicals from water.

_____ 5. Filters are used during water treatment to remove bacteria from water.

_____ 6. People in wealthy nations waste more water than people in poor nations.

_____ 7. The single biggest use of water is for industry.

_____ 8. Water-saving toilets use only about half as much water as regular toilets.

_____ 9. When communities ration water, they ban its use by certain households.

_____ 10. Chemicals are added to untreated water to cause solids to clump together.

Lesson 21.3: Critical Reading

Name___________________ Class______________ Date________

Read this passage based on the text and answer the questions that follow.

Conserving Water

Conserving water means using less of it. Of course, this mostly applies to people in the wealthy nations who have the most water and also waste the most. Irrigation is the single biggest use of water. Overhead irrigation wastes a lot of water. Drip irrigation wastes less. In drip irrigation, water pipes run over or just under the surface of the soil. There are tiny holes in the pipes close to the plants. Water slowly drips out of the holes and soaks into the soil around the plants. Very little of the water evaporates or runs off the ground.

Some communities save water with rationing, especially during droughts. Typically,, rationing saves water by banning its use for certain purposes. For example, communities may ban lawn watering and car washing. People may be fined if they use water for these purposes.

Individuals can conserve water at home in several ways. If they save even a few gallons a day, it will make a big difference over the long run. The best place to start saving water is in the bathroom. Toilet flushing is the single biggest use of water in the home. Showers and baths are the next biggest use. People can follow these tips to save water at home:

  • Install water-saving toilets. They use only about half as much water per flush. A single household can save up to 20,000 gallons of water a year with this change alone.
  • Take shorter showers. Taking a 5-minute shower instead of a 10-minute shower saves up to 50 gallons of water per shower.
  • Use low-flow shower heads. They use about half as much water as regular shower heads. They save thousands of gallons of water a year.
  • Fix leaky shower heads and faucets. All those drips really add up. At one drip per second, more than 6,000 gallons go down the drain in a year because of a single leaky faucet.
  • Don’t leave the water running while brushing teeth. This could save as much as 10 gallons per brushing.
  • Landscape around the house with plants that don’t need extra water. This could result in a huge savings in water use.


  1. Why does drip irrigation waste less water than overhead irrigation?
  2. When and how do communities ration water?
  3. Identify three ways that people can save water in the home.

Lesson 21.3: Multiple Choice

Name___________________ Class______________ Date________

Circle the letter of the correct choice.

  1. To protect the water supply, you should dispose of motor oil by
    1. pouring it down the drain.
    2. spreading it over the ground.
    3. letting it run into a storm sewer.
    4. none of the above
  2. If pet wastes pollute the water supply, they can
    1. add nitrogen to the water.
    2. cause overgrowth of algae.
    3. pollute the water with bacteria.
    4. all of the above
  3. The goal of all water treatment is to
    1. make water pure enough to drink.
    2. remove unwanted substances from water.
    3. make water safe enough to return to the natural environment.
    4. all of the above
  4. Which processes are involved in treating drinking water?
    1. coagulation
    2. sedimentation
    3. filtration
    4. all of the above
  5. Ways that people can conserve water include all of the following except
    1. fixing leaky faucets.
    2. taking shorter showers.
    3. using low-flow shower heads.
    4. leaving on the water while brushing teeth.
  6. The single biggest use of water in the home is
    1. toilet flushing.
    2. cooking.
    3. cleaning.
    4. laundry.

Lesson 21.3: Matching

Name___________________ Class______________ Date________

Match each definition with the correct term.


_____ 1. process in water treatment in which small particles are separated from water

_____ 2. process in water treatment in which large particles settle to the bottom of the water

_____ 3. series of processes to improve the quality of water

_____ 4. process in water treatment in which chlorine is added to water

_____ 5. preserving a resource by using less of it

_____ 6. contamination with chemicals, waste, or other harmful substances

_____ 7. process in water treatment in which solids in water clump together


a. water treatment

b. pollution

c. conservation

d. sedimentation

e. filtration

f. coagulation

g. disinfection

Lesson 21.3: Fill in the Blank

Name___________________ Class______________ Date________

Fill in the blank with the appropriate term.

  1. During water treatment, __________ is added to water to kill microbes.
  2. A(n) __________ irrigation system wastes a lot of water.
  3. A(n) __________ irrigation system wastes very little water.
  4. When communities place limits on water use, this is called __________ of water.
  5. In a home, the __________ is the room where most water is used.
  6. The letters ________ stand for the U.S. government agency in charge of protecting the environment.
  7. The U.S. law known as the __________ Act requires testing and cleanup of polluted water.

Lesson 21.3: Critical Writing

Name___________________ Class______________ Date________

Thoroughly answer the question below. Use appropriate academic vocabulary and clear and complete sentences.

Outline the steps in which water is treated for drinking. Explain how each step improves the quality of the water.

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