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6.16: Water Pollution

Difficulty Level: Basic Created by: CK-12
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Do you live near water? Do you see pollution?

Water pollution is a worldwide problem. Almost anything released into the air or onto the land can end up in Earth’s water.

Surface Water Pollution

Water pollution may come from one source. For example, chemicals from a factory may empty into a stream. Water pollution may come from more than one source. For example, chemicals may rain from the air into that same stream. It is much more difficult to control pollution from more than one source.

In the developed nations there are three main sources of water pollution:

  1. Agriculture.
  2. Industry.
  3. Municipal, or community.


Chemicals that are applied to farm fields include fertilizers and pesticides (see Figure below). Excess chemicals can be picked up by rainwater. The chemicals can end up in streams, ponds, lakes or the ocean. Dissolved fertilizer causes tremendous numbers of water plants and algae to grow. This can lead to dead zones where nothing can live in lakes or the coastal oceans.

Waste from livestock can also pollute water. The waste contains pathogens that can cause diseases. Many farms in the U.S. have thousands of animals. These farms produce millions of gallons of waste. The waste is stored in huge lagoons, like the one in Figure below. Many leaks from these lagoons have occurred.

This is a pond of hog manure. Check out the vehicles at the bottom of the picture for scale.


Factories and power plants may pollute water with harmful substances.

  • Many industries produce toxic chemicals.
  • Nuclear power plants produce radioactive chemicals.
  • Oil tanks and pipelines can leak.

Oil spills are hard to clean up and kill a lot of wildlife.


“Municipal” refers to the community. Households and businesses in a community can pollute the water supply. Municipal pollution comes from sewage, storm drains, septic tanks, boats, and runoff from yards. For example:

  • People apply chemicals to their lawns. The excess can run off into surface waters.
  • People may dispose of harmful substances incorrectly. For example, motor oil must not be drained into a storm sewer.
  • Municipal sewage treatment plants dump treated wastewater into rivers or lakes. But the wastewater may not be treated enough or for everything.


  • Pollution enters water from municipal, industrial, agricultural sources.
  • Fertilizer runoff can create dead zones in the ocean.
  • People pollute water when they apply excess chemicals to their lawn. They may also dispose of pollutants incorrectly.


Use this resource to answer the questions that follow.


Click on non point pollution and the various pushpins.

  1. What type of pollutants do houses create?
  2. How do pollutants from cars enter the groundwater?
  3. How does farming cause pollution?
  4. How do towns contribute to water pollution?
  5. How do sinkholes contribute to water pollution?


  1. Why do large animal farms cause a lot of pollution?
  2. What are the three major sources of water pollution in the developed world?
  3. How do you and your family pollute water?

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pathogen A microorganism that causes disease.
radioactive An atom that can undergo spontaneous breakdown to become another type of atom.

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Difficulty Level:
6 , 7
Date Created:
Jan 04, 2013
Last Modified:
Dec 23, 2016
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