Are you trying to have what is on the ceiling reflect from water? If so, you could just place a copy of the ceiling object inside the water, then show/hide it based on floor triggers. So, for example, when someone approaches the water there are floor triggers that create a copy of the ceiling object inside the water, and when someone jumps in the water there are other triggers that remove it (or the original floor triggers remove it OnDeactivate).
Probably a cheesy work around, but could be fun and easy way to achieve this
