Water Sources
Lift
Lift is the vertical distance a pump must raise water from a static source up to its intake when drafting. Atmospheric pressure sets the ceiling on how high water can be lifted, and that ceiling drops with altitude.
When drafting, the pump does not pull water up so much as remove air and let the atmosphere push it. Since the atmosphere can only push so hard, there is a theoretical maximum lift — and friction and a practical safety margin make the usable lift lower still.
The higher the lift, the harder the draft and the less water the pump can ultimately move. Choosing a drafting spot close to the water level, not far above it, keeps the lift manageable.
Where this shows up
Calculator
Drafting & Lift