Wastewater Detention Time Calculator

Find hydraulic detention time in a tank.

Detention time 12

Detention time (days) 0.5

Formula: detention time = tank volume ÷ flow rate

Step-by-step with your numbers:

1. Values used:

2. Tank volume = 50,000 gal

3. Flow rate = 100,000 gal/day

5. Detention time = 12

6. Detention time = Tank volume / Flow rate = 50,000 / 100,000 = 0.5days

Did we solve your problem today?

Hydraulic detention (retention) time is how long water stays in a treatment tank.

The math behind it

detention time = tank volume ÷ flow rate (use consistent units); × 24 for hours.

50,000 gal ÷ 100,000 gal/day → 0.5 day (12 h).

Why it matters?

It sets how long biological/settling processes have to work.