Water pollution can occur from sewage, fertilizers, pesticides, herbicides, and toxic substances. Sewage from human waste can spread pollution and disease if not properly processed. Fertilizers can contaminate drinking water and cause eutrophication when too much runs off into streams, promoting excessive algal growth that depletes oxygen levels and kills aquatic life. Pesticides and herbicides washed into rivers also kill plant and animal life. Toxic chemicals build up in food chains and can cause health issues.

1. Water Pollution

2. Water Pollution
Water can be polluted by
• SEWAGE
• FERTILISERS
• PESTICIDES/HERBICIDES
• TOXIC SUBSTANCES

3. Sewage
Sewage is human
waste. Without
careful processing
it can cause
pollution and
disease.

4. Fertilisers
• CONTAMINATE drinking
water
• EUTROPHICATION

6. EUTROPHICATION
If too much fertiliser is used
it runs off into streams and
rivers.
The fertiliser makes river
plants and algae grow really
fast

7. The stream cannot support so
much plant life, so the plants
start to die.
As the plants die, they are
rotted by bacteria which use up
all the OXYGEN in the stream

8. Lack of oxygen causes the
fish and other animals in the
stream to die.

9. PESTICIDES and
HERBICIDES can be washed
into rivers and streams
This kills plant and animal life

10. Toxic Chemicals
• Toxic chemicals can build
up in food chains causing
birth defects and
reproductive problems.

11. The Minimata Bay Tragedy