If you look, there is no actual bridge between 2 and 3: the tube is actually sealed, so the only jars that can receive water are 1, 2, 4 and 5.
In theory, this actually highly depends on the velocity of the water; those are incredibly thin tubes, so if the water came out very fast, 1 would fill up before it had a chance to drain.
If we assume the water is coming out at a reasonably sluggish pace, enough for it to push through the tubes before 1 can be fully filled, the way fluids like to work means the fluid level will try to equalise in every container, so two will start to fill up, which will fill up four and five, and they should rise in level at an equal pace. However, because 5 has the lowest volume, if they all increase at an equal pace 5 will fill first.
This is also loss.jpg, but that's not relevant.


























