Hydraulic Retention Time Calculator

Find the average time water spends in a reactor.

Retention time 12

Retention time (days) 0.5

Formula: HRT = reactor volume ÷ flow rate

Step-by-step with your numbers:

1. Values used:

2. Reactor volume = 200

3. Flow rate = 400 m³/day

5. Retention time = 12

6. Retention time = Reactor volume / Flow rate = 200 / 400 = 0.5days

Did we solve your problem today?

Hydraulic retention time (HRT) is the average time fluid stays in a reactor.

The math behind it

HRT = reactor volume ÷ flow rate (consistent units).

200 m³ ÷ 400 m³/day → 0.5 day (12 h).

Why it matters?

Longer HRT gives reactions and microbes more time to act.