Answer 1

Main causes of water pollution are:

• Chemical waste, industrial waste and agricultural processes.
• Thermal waste from nuclear and thermal power plants.
• Sewage and garbage.

Prevention of water pollution:

• Domestic sewage should be treated before being discharged into rivers.
• Using of non-biodegradable substances like detergents should be stopped.
• Trees and plants must be planted along the banks of rivers.
• Purification of water bodies should be carried out.
• The waste products of industries should be treated before they are discharged into rivers.