The ten-metre ceiling.
No pump on Earth can suck water higher than about 10.33 m — however hard it pulls. A pump doesn't lift the water; the weight of the atmosphere below does, and there's only so much of it to push with.
0 m
vacuum — zero pressure
atmosphere pushes down, P₀
Altitude P
P₀ ∝ h
0 mhigher up · thinner air · lower ceiling5,000 m
Maximum lift height
mthe ceiling.
water, sea level
impossible beyond this line
Try
This is the barometric limit: h = P₀/(ρg), the column height at which the weight of the liquid exactly balances atmospheric pressure. A pump — or a mouth, or a "suction" of any kind — doesn't pull liquid upward; it only removes air from above the column, and it's the full weight of the atmosphere pressing on the open reservoir below that pushes the liquid up to fill the emptied space. Once the pump has produced a perfect vacuum, there is nothing left to improve: no stronger pump, no better seal, gets the column an inch higher, because the ceiling is set by the atmosphere outside the tube, not by anything happening inside it. Evangelista Torricelli discovered this in 1643 using mercury rather than water precisely because mercury's much higher density shrinks the same physics down to a benchtop-sized 760 mm tube — the mercury barometer. This is the hydrostatic sibling to straw-hose-flow.html's viscous-drag straw problem: that page is about the effort of pushing a liquid sideways through a narrow tube; this one is about a hard ceiling on pushing any liquid straight up, no matter how wide the tube or how strong the vacuum. Altitude pressures use the standard-atmosphere approximation and are illustrative, not survey-grade.