Which of the following is a method of sterilisation used in water treatment?

Chlorination is a widely used method of sterilization in water treatment. This process involves adding chlorine or chlorine compounds to water in order to eliminate pathogenic microorganisms, such as bacteria and viruses, that could cause disease. The chlorine acts as a disinfectant and is effective in killing or inactivating these harmful organisms, ensuring that the water is safe for consumption and other uses.

Boiling is indeed a method for sterilizing water but is less practical on a large scale in municipal water treatment processes, as it can be energy-intensive and time-consuming for large volumes. Filtration is a process that removes particulate matter and some bacteria but does not effectively eliminate all microorganisms, particularly viruses. Precipitation typically involves chemical reactions that involve settling out solids from a solution rather than directly sterilizing water, making it less relevant as a method of disinfection. Therefore, chlorination stands out as the most effective method for ensuring microbial safety in treated water.