Chemistry
Detention Time Calculator
Find how long water stays in a tank or basin at a given flow rate.
Your inputs
Change any value to update the result instantly.
Detention time
2 hours
In minutes
120 min
In days
0.0833 days
Turnovers per day
12
Reading
Comfortable contact time for most treatment steps
Volume and flow must use matching units. This is the ideal plug-flow time; short-circuiting and dead zones mean real contact time is usually shorter.
What this calculator does
Divides tank volume by flow rate to give the average time water spends in a basin.
What your result means
How long treatment has to act on the water passing through.
Formula and working
t = V / Q
- 1
Collect the inputs
Tank or basin volume = 500 m³; Flow rate = 250 m³/h
- 2
Apply the formula
t = V / Q
- 3
Result
Detention time = 2 hours
Frequently asked questions
Symbols and assumptions
- t
- Detention time
- V
- Volume
- Q
- Flow rate
- • Steady flow.
- • Volume and flow are in matching units.
Sources and review
Reviewed 2026-09-22 · Next review 2027-09-22
- • Real basins short-circuit and have dead zones, so actual contact time is usually shorter than the ideal figure.
Important limitation
This is an educational estimate based only on the values and formula shown. Verify current rates, rules, units, and professional standards before relying on the result. It is not personalized financial or investment advice.
Report a mistake or request an improvement
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