Chlorine CT Value
Calculates CT (concentration × contact time) for chlorine disinfection and compares it against a required CT for microbial inactivation. Used for surface water discharge compliance with coliform limits under the Surface Water Treatment Rule.
Chlorine CT Value
Calculate CT (concentration × time) for disinfection and check it against a required CT.
Enter all values above to calculate.
When you'd use this
Calculates CT (concentration × contact time) for chlorine disinfection and compares it against a required CT for microbial inactivation. Used for surface water discharge compliance with coliform limits under the Surface Water Treatment Rule.
Category
DisinfectionFree or total chlorine residual measured at the contact basin effluent.
Time for 90% of the flow to pass through the basin. T10 is the basin's theoretical detention time × baffling factor (typically 0.3–0.7).
Optional target CT from your NPDES permit or the applicable LT2ESWTR log-reduction table.
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Each calculator opens onto its own page with the formula, variable definitions, a worked example, and related operator math.
EPA Disinfection Profiling and Benchmarking Guidance Manual — Surface Water Treatment Rule / LT2ESWTR.
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