Ah whatever, so I used the wrong terminology, I had basically the right idea (btw, I said "let into the top of the tank", but what I meant to say was "let through the top of the tank"-or at any place above the water level for that matter).Burko;4322363; said:"That isn't exactly correct...The reason the water stays in place is because the vacuum keeps it from coming out as long as air isn't let into the top tank"
That isn't exactly correct...
There is no vacuum... by admission the tank is full of water and/or air.
Pressure is the key factor.