If you had a 100 foot rigid pipe, fill it with water, cap both ends, stand the pipe straight up, remove the lower cap, all but 34 feet of water would come out of the bottom of the pipe.
Increase the atmospheric pressure, you can increase the height of supported water. Decrease the atmospheric pressure, you decrease the height of the atmospheric pressure.
We haven't even gotten to the siphon part yet, and we've limited ourselves to supporting a column of water equal to the atmospheric pressure on the bottom of the column of water.
56 + 34 = 90.