Engineering Tool

Retention Time Calculator

Estimate the hydraulic retention time for a tank or basin.

Formula

t = V / Q where V = volume (m³) and Q = flow (m³/h).

Variables

V — tank/basin volume (m³)
Q — flow rate (m³/h)

Example

100 m³ tank at 25 m³/h: t = 100/25 = 4 hours.

Application

Useful for preliminary water-treatment and storage design.

Limitations

This is a nominal hydraulic retention time. Actual mixing, short-circuiting and process requirements must be considered.

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Preliminary calculation only. Not a certified engineering design. Final design must be validated by a qualified professional where required.