What is the term for the distance between the static water level and the pumping water level?

• A. Drawdown
• B. Headloss
• C. Water level difference
• D. Pumping head

Answer: (A)

Drawdown is the vertical drop of the water surface caused by pumping. It’s specifically the distance between the static water level (the level when nothing is being pumped) and the pumping water level (the lower level that occurs while pumping). This measure is central to understanding how much the aquifer responds to a given pumping rate and how much water a well can supply over time.

Think of it as the result of removing water from the well and the surrounding aquifer: as water is pumped out, pressure in the surrounding rock drops and the water table around the well declines until the pumping rate and recharge reach a balance. The magnitude of drawdown depends on how fast you pump, how permeable the aquifer is, how much stored water is available, and the well design.

Headloss refers to energy losses in pipes due to friction, not the vertical drop in the well water level. Water level difference isn’t a standard term in this context, and pumping head describes the energy needed to lift water to the discharge point, not the vertical distance between water levels in the well.