Which chlorination method is a very good disinfectant with a stable effect and is 5% chlorine?

• A. Chlorine Gas
• B. Bleach
• C. High-test calcium hypochlorite
• D. Ozone

Answer: (B)

Bleach, a sodium hypochlorite solution around 5% available chlorine, provides rapid disinfection and leaves a stable residual to continue inactivating microbes after application. In water, the disinfecting agent is hypochlorous acid formed from the chlorine in the solution, which effectively oxidizes essential cellular components of microbes. The presence of that residual chlorine means the disinfecting effect persists, giving lasting protection even after the initial dose.

Chlorine gas is powerful but hazardous to handle andStore; it requires specialized equipment and safety controls. High-test calcium hypochlorite is concentrated and useful, but it can be unstable in storage and handling; it may release chlorine gas under improper conditions. Ozone is a strong oxidant and not a chlorine-based disinfectant, and it does not provide a lasting residual once treatment ends, plus it needs on-site generation and dedicated equipment.

So, using a 5% chlorine bleach formulation combines effective disinfection with a stable residual, practicality, and broad applicability.