I am trying to design a water vessel system that maintains it's water level as it is consumed. In item 1. It's a simple water barometer, where the height of water in the column can be supported by atmospheric pressure until 10.34. In item 2. There are two columns that are open to atmosphere that are higher than the top of X reservoir (accordion-style that can be compressed down to create a U shaped vessel). Water will be sucked out of the side columns. What force would I need to apply to the top of that vessel to maintain the water level at the very top of the column. I tried Patm=F/A on the X reservoir, but that seems really high. I am having a hard time modelling this. My goal is the smallest force possible to maintain the height of water. Any help would be much appreciated.