Which one of the following is NOT the common method of disinfection of water?

Explanation:

Disinfection of water:

• Disinfection may be defined as the process of destruction or inactivation of harmful microorganisms in water either by physical process or chemical process. The physical process includes heating, ultraviolet radiation, etc. and the chemical process includes the addition of disinfectants such as chemicals. 
• Disinfection can be distinguished from sterilization. In the sterilization process, all organisms are usually killed by a physical phenomenon such as boiling for a long period whereas in disinfection disease or illness-causing microorganisms are reduced to such a low level that no infection or disease results when the water is used for domestic purposes including drinking water.
• Disinfection is an essential minimum treatment requirement for any drinking water and it is the final process in the chain of water purification.

Minor methods of disinfection of water:

• Treatment with excess lime,
• Treatment with ozone,
• Treatment with KMnO₄,
• Treatment with F and Br in the form of pills,
• By use of sodium hypochlorite (NaOCl
• By ultraviolet rays, etc.
• By boiling

Major methods of disinfection of water:

• Chlorination