Detention Time (HRT) Calculator
Calculate hydraulic retention time for sedimentation tanks, aeration basins, and clearwells from tank dimensions and flow.
Formula
HRT = V ÷ Q
V = tank volume, Q = flow. Theoretical detention time assumes ideal plug flow / complete mixing.
HRT = V ÷ Q
V = tank volume, Q = flow. Theoretical detention time assumes ideal plug flow / complete mixing.
Typical detention times
| Unit | HRT |
|---|---|
| Primary clarifier | 1.5 – 2.5 h |
| Aeration basin (conventional) | 4 – 8 h |
| Secondary clarifier | 2 – 3 h |
| Chlorine contact tank | ≥ 30 min at peak flow |