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12.29: Preserving Water Sources

Difficulty Level: At Grade Created by: CK-12
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Do we have an infinite supply of drinkable water?

No. In fact, in many parts of the world, finding clean drinkable water is difficult. This can lead to various serious health issues. Hundreds of millions of people world-wide are thought to live in areas where obtaining safe water is difficult. This makes preserving water resources an important global issue.

Preserving Water Sources

It might seem like there is plenty of water on Earth, but that's not really the case. Water is a limited resource. That means that it is used faster than it is replaced. Theoretically, at some point in time, the supply of fresh water could run out. Though this is unlikely, it is possible. But it is a significant issue in parts of the world with large populations. As these populations continue to grow, the supply of water becomes an increasingly important issue.

Even though we have lots of water in our oceans, we cannot use that water whenever we want. It takes special equipment and a lot of energy (and money) to convert salt water into fresh water. Of all the water on Earth, only about 1% can be used for drinking water. Almost all of the rest of the water is either salt water in the ocean or ice in glaciers and ice caps. As a result, there are water shortages many places in the world. Since we have such a limited supply of water, it is important to preserve our water supplies. Therefore, steps have been taken to prevent water pollution. Technologies have also been developed to conserve water and prevent water pollution.

Preventing Water Pollution

In the U.S., concern over water pollution has resulted in many federal laws. Some of these laws go all the way back to the 1800s! The laws prohibit the disposal of any waste into the nation’s rivers, lakes, streams, and other bodies of water, unless a person first has a permit. Growing concern for controlling water pollutants led to the enactment of the Clean Water Act in 1972. The Clean Water Act set water quality standards. It also limits the pollution that can enter the waterways. Other countries are also actively preventing water pollution and purifying water (Figure below).

A water purification station in France. Contaminants are removed to make clean water.

Wastewater Treatment

Fresh water is also preserved by purifying wastewater. Wastewater is water that has been used for washing, flushing, or manufacturing. It includes the water that goes down your shower drain and that is flushed down your toilet. Instead of dumping wastewater directly into rivers, wastewater can be purified at a water treatment plant (Figure below). When wastewater is recycled, waterborne diseases caused by pathogens in sewage can be prevented. What are some ways you can save water in your own house?

Wastewater treatment plant.


  • Clean Water Act: U.S. federal law that set water quality standards.
  • limited resource: A resource that is used faster than it can be made.
  • pathogen: An organism that causes disease.
  • wastewater : Water that has been used for washing, flushing, or manufacturing.
  • waterborne disease: Diseases that spread through fresh water sources.
  • water pollution: Pollution due to contaminants entering the water supply.


  • The United States, as well as other countries, have passed laws to preserve water quality and prevent water pollution.
  • In the U.S., we also preserve our fresh water sources by purifying our wastewater.


Use the resource below to answer the questions that follow.

  1. What kind of material can be found in our water?
  2. What kinds of problems can algae cause to our water resources? How is algae good?
  3. What is turbidity a measure of? What can this information tell you about a water resource?
  4. How is the pH of the Clackamas River related to river flow? What does this relationship suggest is causing the pH increase?


  1. How has the United States government tried to preserve our water sources?
  2. Why is wastewater treatment important?


Clean Water Act

Clean Water Act

U.S. federal law that set water quality standards.
limited resource

limited resource

Resource that is used faster than it can be made.


Organism that causes disease.


Water that has been used for washing, flushing, or manufacturing.
water pollution

water pollution

Pollution due to contaminants entering the water supply.
waterborne disease

waterborne disease

Diseases that spread through freshwater sources.

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Difficulty Level:
At Grade
7 , 8
Date Created:
Nov 29, 2012
Last Modified:
Apr 15, 2016
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