Wouldn't scale and viscosity play a role? Seriously, imagine a river vs a capillary tube. Also how many dimensions? And forces involved? Is that a blockage between 2 and 3? Are the walls breakable? How will the fluid hold air? Are the lines into structure 5 lower than the walls? Is this in a vacuum?
There is no mention of any fluid involved, just a faucet. So lets think inside of the box and assume we have some form of 2d-gravity and it is going to rain a newtonian fluid? I think most surface area on the top is draining into 5. If it snows the whole sheet can turn white and the problem is gone, too.