ENVIRONMENTAL • DISINFECTION

Chlorination CT calculator

Compute CT = residual chlorine × contact time, and compare against a target CT requirement. Intended as a quick check only; always follow your local regulations and design guidelines.

Units: C in mg/L, T in minutes, CT in mg·min/L.

Inputs

Residual chlorine C (mg/L)

Contact time T (min)

Required CT (mg·min/L)

Results

Actual CT (mg·min/L)

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Required time T_req (min)

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Margin vs requirement

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CT_actual = C × T. If CT_req > 0, T_req = CT_req / C. Margin is reported as CT_actual − CT_req. Positive margin ⇒ requirement satisfied.