Changes caused by human activities (pollution) –water pollution

Welcome to class.




INTRODUCTION: In previous classes, we learnt about our environment and what it consists of. We saw how the environment affects us and we in turn also have influence on our environment. The environment we know consists of living and nonliving things. The living things are made up of plants and animals all interacting with themselves.



Our environment is made up of living and non-living components. The living components are called biotic factors, while the nonliving components are called abiotic components. Pollution is the introduction of harmful substances into the natural environment which causes an unfavorable change in the environment. The harmful substances are called contaminants. These contaminants make the environment unsafe for plants and animals, thereby becoming a threat to health and constituting hazards to the living things.

Pollutants are substances that can contaminate the environment. They can be in liquid, solid or gaseous forms.



There are three types of pollution: namely

  • Land Pollution
  • Air Pollution
  • Water Pollution


WATER POLLUTION: Water pollution occur when water pollutants are released or introduced into water bodies making it unfit for consumption.


Causes/sources of Water Pollution

  • Untreated sewage released into water bodies.
  • Human faeces, waste, or dead plant and animals dumped into water bodies
  • Oil leakages (oil spillage) from tanks and pipes into rivers and other water bodies.
  • Liquid wastes from industries released into water bodies.



Effects of Water Pollution.

  • Water pollution causes the spread of water borne diseases
  • Harmful contaminants introduced into water bodies kills water organisms. Like fish, crabs,
  • The harmful chemicals released into water bodies renders it unfit for drinking, cooking or even washing.
  • When water is polluted, it produces bad odour
  • Water pollution reduces the amount of oxygen made available to water organisms


Control of water pollution

  • Oil spillage should be avoided
  • Dumping of refuse into water bodies should be avoided
  • The use of chemicals to catch fish should be discouraged
  • Industrial waste should not be dumped into water bodies,
  • Water treatment and water waste recycling should be encouraged
  • People should be educated on the dangers of polluting water bodies.



  1. What is water pollution?
  2. Mention three water pollutants.
  3. Give three ways by which we can control water pollution.





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