Bleaching powder is added in water used for drinking purpose. The role

Bleaching powder is added in water used for drinking purpose. The role of bleaching powder in this case is

of disinfectant
of bleaching agent
to remove impurity
to decrease the pH
This question was previously asked in
UPSC CAPF – 2012
Bleaching powder (Calcium hypochlorite, Ca(ClO)2) is commonly added to water for drinking purposes because it releases chlorine, which acts as a powerful disinfectant. Chlorine kills or inactivates harmful microorganisms such as bacteria, viruses, and protozoa that can cause waterborne diseases.
The disinfecting action of bleaching powder is due to the hypochlorite ion (ClO⁻) and hypochlorous acid (HClO) formed when it dissolves in water. HClO is a strong oxidizing agent.
While bleaching powder is a bleaching agent in other contexts (due to its oxidizing properties), its primary role in water treatment for drinking is disinfection. It does not directly remove dissolved impurities or significantly decrease the pH of the water at typical treatment concentrations.