What are the 3 chlorination methods?

• A. UV, ozone, and chloramine
• B. HTH, chlorine gas, and bleach/sodium hypochlorite
• C. Steam distillation, boiling, and chilling
• D. Calcium hypochlorite, peracetic acid, and iodine

Answer: (B)

Chlorination methods refer to the ways chlorine is introduced into drinking water to disinfect it. The three chlorine-based sources most commonly used are chlorine gas, liquid sodium hypochlorite (bleach), and solid calcium hypochlorite (HTH).

Chlorine gas provides rapid disinfection but requires specialized equipment and safety measures to handle the gas and scrubbing systems to remove any released gas. Liquid sodium hypochlorite is easy to store and dose, making it convenient for many treatment settings, especially where large volumes are processed daily. Solid calcium hypochlorite, used as granules or tablets (HTH), is portable and simpler to store, releasing chlorine when dissolved in water.

Other disinfection approaches like UV and ozone do not involve adding chlorine, so they aren’t considered chlorination methods. Chloramine, while a chlorine‑based disinfectant formed by combining chlorine with ammonia, isn’t a primary chlorine delivery method itself. It’s typically used to maintain residual disinfection in the distribution system, not as one of the main means of chlorinating water.