Drawdown Time (Detention Tanks)

01/01/26

“How long does it take for detention tanks to empty their stored water?”

Detention tanks hold stormwater and release it slowly over time to prevent flooding. The amount of time it takes to empty the detention tanks, also known as the Drawdown Time, is dependent on a variety of factors, such as the volume of filtration, orifice area, acceleration due to gravity, and maximum hydraulic head above the orifice centerline. Detention tank drawdown is vital for hydrological engineering calculations. 

image credit: https://www.polymaster.com.au/