Question

whatare different waysin water gets contaminated

Answer 1

There are 3 different types of contaminants of water- (1)Chemical contaminants, which include both organic and inorganic contaminants,(2) Microbial contaminants and (3) Radioactivity. Contamination in a wider sense is defined as those components present in water which may cause harm or damage cause for which the water is being used. For example, presence of Coliform does not necessarily pose a threat to the Boiler water as it does during consumption by human, While a sample of hard water may damage the Boiler forming scale. Even an extreme higher or an extreme lower pH may also be considered as contaminant in drinking water. 
Now comes the question of source of contamination. Mainly soil and water (Sewage and wastes), contaminants carried by flood and other natural disasters, surface contamination by animals, aerial contamination are the sources. River water gets contaminated through disposal of sewage; while fertilizers and pesticides from land enter into underground water adding to chemical contamination. The nature of the soil and the minerals present in a particular place, e.g., mineral oils.Animals' decomposed body parts adding to nitrites and nitrates,etc. Thus, sources of contamination are enormous.

Answer 2

Water gets contaminated by the addition of:
1. Agricultural chemicals: These chemicals get carried away to the water bodies due to rains and floods which lead to water pollution.
2. Industrial wastes: Industries release harmful chemical wastes into water sources, thereby polluting them.
3. Sewage wastes: Waste materials from kitchens, toilets, and laundry sources are also responsible for contaminating water. 
Hope this could be helpful !!