Detention Time
Detention time = volume / flow in min, hr, days; pass/fail vs target.
Example
You enter
- Tank volume (gal) 50000
- Flow (GPM) 350
- Target (min, optional) 120
You get
- Minutes 142.857
- Hours 2.381
- Pass target PASS
Checked against published worked examples from: USEPA.
Details, formula, and sources
Formula or tableDetention 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).
Source and editionEPA Surface Water Treatment Rule (SWTR) 40 CFR 141 Subpart H by section. EPA Disinfection Profiling and Benchmarking Guidance Manual by name.
Free access40 CFR 141 free at ecfr.gov. EPA guidance manual free at epa.gov.
What governsEstimate. Operator of record and primacy agency govern.
API field namestank_volume_gal, flow_gpm, target_minutes, minutes, hours, pass_target
- Theoretical time volume / flow, the plug-flow (theoretical) time; for CT credit use T_10, typically 0.1-0.7 x this by baffling class from a tracer study, which this tile does not applyEPA Disinfection Profiling Guidance