Water Pollution

The coliform bacteria, if present in water, contaminates water and the water is not safe to drink.

'Point source pollution' means the pollution of water reserves by a single and definite source of pollution. Oil spillage from a ship in the ocean is an example of point source of pollution 

Due to various types of pollution, concentration of oxygen decreases in the water which is hazardous to aquatic life and humans beings for survival. This is called oxygen depletion.

If water consumed by humans is contaminated with microorganisms like coli, it can cause cholera.

It is a microbiological contamination.
We can understand that water can be polluted by the following ways:
(1) Microbiological
(2) Industrial
(3) Agricultural
(4) Petrochemical
(5) Sewage disposal
(6) Radiological
(7) Thermal pollution

Water can be conserved by following the given measures of water pollution.

Thermal pollution makes water gain or lose temperature, which affects the aquatic life in a bad way. Thermal pollution is the result of release of very hot water or very cool water from industries into water bodies.

Ozone is a powerful oxidizing agent, which kills all types of bacteria, virus, and protozoa present in the water and makes water safe to drink. Before the ozone treatment, the water must be cleared of all types of mud, sewage and chemicals. Ozone is a molecule formed by a combination of three oxygen atoms.

Depletion of oxygen is caused by different pollutions like chemical contamination, garbage contamination, and agricultural contamination, which kills aerobic bacteria that are eco friendly and develops anaerobic bacteria which are harmful bacteria.

Carbon dioxide is present in large quantity in environment. So, it is called as pollutant.
All other options are called contaminants because they are present in small quantities.
A substance which enters environment due to man's activities and affects it in a bad way is called contaminant.
A substance which is present in large quantity in environment and affects it in bad way is called pollutant.

Ammonia is an inorganic pollutant. An organic pollutant is derived from carbon related compounds and an inorganic pollutant is derived from elements other than carbon. 

'Eutrophication' is a process in which the water body becomes enriched with nutrients. This can be a problem in marine habitats as it can cause algal blooms. The algae may use up all the oxygen in the water leaving none for other marine life. This results in the death of many aquatic organisms such as fishes, which need the oxygen in the water to live.

'Sewage' is the term used for waste water that contains human waste, faeces, urine, laundry waste, etc.

Hepatitis is a water borne disease, which adversely affects the liver of the patient.