Question

Explain the different ways by which water gets polluted.

Answer 1

1. Domestic Sewage.
   Untreated sewage contains impurities such as organic matter from food waste, toxic chemicals from household products and it may also contain disease-causing microbes.
2. Domestic waste and plastics.
    Plastics block drains spreading vector-borne diseases such as malaria and dengue. Waste in water bodies negatively impact aquatic life.
3. Agricultural activities
   a. Fertilizers, pesticides, and insecticides used in agriculture can dissolve in rainwater and flow into water bodies such as rivers and lakes.
   b. This causes an excess of nutrients such as nitrates and phosphates as well as toxic chemicals into the water bodies and they can be harmful to aquatic life.
4. Industrial waste
   a. Many industries release toxic waste such as lead, mercury, cyanides, cadmium, etc.
   b. If this waste is unregulated and is released into water bodies, it negatively impacts humans, plants, animals, and aquatic life.
5. Oil spills.
   Oil spills cause water pollution which is harmful to aquatic life.
6. Thermal pollution. 
   Water used for cooling purposes is discharged back to a river or to the original water source at a raised temperature and sometimes with chemicals. This rise in temperature decreases the amount of oxygen dissolved in water which adversely affects aquatic life.