CBSE Class 8 Answered

Two main causes of water pollution are:

• Industrial effluents, domestic wastes and Sewage: Industries discharge liquid and solid wastes into water. This consists of chemicals like lead, mercury etc. which pollutes water. House waste water gets mixed with sewage like detergents, animal dung, faecal material etc and is drained out through municipal drains and poured into rivers and lake polluting water.
• Use of Fertilisers: Farmers use fertilisers on their fields. Many fertilisers contain phosphate. When phosphate mix with water, it leads to rapid growth of algae polluting water.