Enter the total volume of liquid in a reservoir and the flow rate out of the reservoir into the calculator to determine the detention time.
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Detention Time Formula
The following formula is used to calculate the detention time of a reservoir.
DT = V / Q
- Where DT is the detention time
- V is the total volume of the tank or reservoir
- Q is the flow rate out of the reservoir
To calculate the detention time, divide the total volume by the flow rate.
Detention Time Definition
A detention time is defined as the total amount of time it takes a given volume of water to pass through a tank or reservoir at a given flow rate.
How to calcualte detention time?
Example Problem #1:
First, determine the size of the tank. For this example, we are looking at a tank that has a volume of 500 cubic feet (ft^3).
Next, determine the flow rate out or into the tank. For this problem, the water is filling the container at a rate of 5 cubic feet per second (ft^3/s)
Finally, use the formula above to calculate the detention time:
DT = V / Q
= 500 / 5
= 100 seconds
Example Problem #2
In this next problem, we are looking at a much larger reservoir that has a total volume of 20,000 Liters (L).
The flow rate out of the reservoir is measured to be 500 liters per second (L/s)
Using the formula as we did in example 1, the detention time is calculated as:
DT = V / Q
= 20,000 / 500
= 40 seconds
