Detention Time

Detention time = volume / flow in min, hr, days; pass/fail vs target.

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Formula and source

Detention time = volume / flow. Used for chlorine contact (CT for Giardia / virus inactivation per EPA SWTR), flocculation, sedimentation. CT = concentration (mg/L) × T_10 contact time (min).

EPA Surface Water Treatment Rule (SWTR) 40 CFR 141 Subpart H by section. EPA Disinfection Profiling and Benchmarking Guidance Manual by name.

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Rough Logic answers the math question the working professional asks on the job. The site is a calm, fast, ad-free, account-free, ever-free reference. It does not interpret code. It does not replace the licensed professional. It does not store your inputs. The Authority Having Jurisdiction governs all installations and inspections.