HCH is typically what percentage of available chlorine?

• A. 30%-40%
• B. 65%-70%
• C. 80%-90%
• D. 10%-20%

Answer: (B)

Available chlorine percentage tells you how much of a chlorine product is actually active disinfectant per unit weight. For solid calcium hypochlorite products used in water treatment, the typical available chlorine content is about 65–70%. That higher content means you get more active chlorine per gram, which is why calcium hypochlorite is favored as a solid disinfectant. Other ranges like 30–40%, 80–90%, or 10–20% either reflect different, less common products or concentrations, so they aren’t the standard value for this chlorine source.