Which treatment step is used to reduce disease-causing organisms and is typically mandated for drinking water safety?

• A. Disinfection
• B. Oxidation
• C. Pasteurization
• D. Sterilization

Answer: (A)

Disinfection is the treatment step designed to kill or inactivate disease-causing microorganisms, providing the level of protection needed for safe drinking water. In public water systems this step is required by regulations to ensure pathogens don’t reach consumers, and a disinfectant like chlorine is often added with a residual kept in the distribution network to maintain safety as water travels to taps.

Oxidation targets certain contaminants and can help with taste, odor, and some inorganic pollutants, but it isn’t primarily about eliminating pathogens in drinking water. Pasteurization uses heat and isn’t practical for an ongoing municipal system. Sterilization would kill virtually all organisms, but it’s costly and unnecessary for regular drinking water and would be impractical for distribution.

So the mandated step for reducing disease-causing organisms in drinking water is disinfection.