Drawdown is how far the water level in a well or aquifer falls because of pumping, measured from the level before pumping began.
Drawdown is the fall in water level caused by pumping. It is the difference between the static level before pumping, h₀, and the level at a given time, h. It depends on the pumping rate, how long the pump has run, the distance from the well and the aquifer's transmissivity and storativity. Low transmissivity gives deep, steep drawdown near the well. Low storativity makes drawdown spread outward faster. Drawdown in a pumped well is usually larger than in the aquifer just outside it. The extra part is called well loss and comes from turbulent flow through the screen and damage around the borehole. A step-drawdown test separates the two, which shows whether a well needs cleaning or a smaller pump. When pumping stops, levels climb back. This rise is called recovery, and it gives a second way to estimate aquifer properties. A well that never fully recovers between pumping cycles shows that it is being overused or that nearby wells are affecting it. Operators keep the pumping level above the pump intake and the top of the screen to protect both the pump and the well.