Rule M16 requires that the Big Water and/or Rain water be touching the mat in the water target. The bonus component requires that the second stacked water be on top of the other big water and touching nothing other than the other big water. These conditions must be observed at the end of the match.
I believe that the interpretation will be that if the container is between the water and the mat, then no points. If the container is a box with an open bottom, then whether or not the second stacked water scores will be based on whether or not any part of it touches the container. If it does, no bonus.
- Vince Shier
co-coach iBOT Brainiacs