The water physics might looks impressive, but it is far from decent in my perspective.

The biggest problem with the current water physics is that the water can flow in any direction except the direction it is flown from and other water flows can't interrupt this. This is basically why all the items flow toward the rightest corner at the start: the leftist water flows are calculated first, making the water flow to the right corner.

The easiest solution I can think of right now is to make water tend to flow in the same direction until it has to turn, but that may makes the water looks less realistic. (Not saying that the current water physics isn't any less realistic, though.)

Also I can't figure out how to not make water render faces behind faces, so the next best solution I can think of is to individually disable the faces that has water flowing through.