4.8 Impact of Water Pollution

2026 Syllabus Objectives

By the end of these notes, you should be able to:

  1. Describe and explain the impact of pollution of fresh water on people and on the environment.
  2. Understand the following specific topics:
    • Global inequalities in sewage and water treatment
    • Risk of infectious bacterial diseases — typhoid and cholera
    • Accumulation of toxic substances from industrial processes in lakes and rivers
    • Bioaccumulation of toxic substances in food chains
    • The effect of acid rain on organisms in rivers and lakes
    • Nutrient enrichment leading to eutrophication

Main Content

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1. Global Inequalities in Sewage and Water Treatment

What is sewage? Sewage is the waste water that comes from toilets, sinks, and drains in homes and businesses. It contains human waste, bacteria, and other harmful substances.

What is water treatment? Water treatment is the process of cleaning water so it is safe to drink. It usually involves filtering out dirt and killing harmful bacteria with chemicals like chlorine.

The inequality problem: Not all countries have the same access to sewage treatment and clean water. There is a huge gap between wealthier and poorer countries:

  • In wealthy, developed countries (e.g. the UK, Germany), almost all sewage is collected through underground pipe systems and treated at special facilities before the water is released back into rivers or the sea. Tap water is cleaned and tested to make sure it is safe.

  • In poorer, developing countries (e.g. parts of sub-Saharan Africa, South Asia), many communities do not have proper sewage systems. Untreated sewage may flow directly into rivers, lakes, or onto the ground. Many people rely on these same water sources for drinking, washing, and cooking.

Why does this matter? When untreated sewage mixes with drinking water sources, it introduces harmful bacteria and viruses into the water. People who drink or use this water can become seriously ill. This is one of the main reasons why diseases like cholera and typhoid are much more common in developing countries than in wealthy ones.

Key point: The inequality in water treatment is not just an environmental issue — it is a matter of life and death for millions of people around the world.

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