Which method of water purification does not kill microorganism?

Water purification methods are categorized into disinfection and physical removal. Boiling kills or inactivates microorganisms by using heat to denature proteins and disrupt essential life processes [3]. Chlorination is a chemical disinfection method where chlorine or hypochlorite is added to water to kill bacteria and viruses by oxidizing organic matter. UV-irradiation is a physical disinfection method that uses short-wavelength electromagnetic light to produce gaps in the nucleic acids of microorganisms, disabling their cellular functions and effectively killing or inactivating them [1]. In contrast, filtration is a physical separation process based on size-exclusion mechanisms. While filtration removes suspended particles, parasites, and some microbes by trapping them in a filter medium or membrane, it does not inherently kill or inactivate the organisms; it merely separates them from the water. Therefore, filtration is the method that does not kill microorganisms.

Sources

1. [3] https://www.epa.gov/sites/default/files/2015-06/documents/disinfection_small.pdf
2. [1] https://www.health.ny.gov/environmental/water/drinking/boilwater/response_information_public_health_professional.htm