When you collide with the water, then that water instance is picked. So the events following that for overlap would only refer to the water you collided with and not other instances of water. In your events what you are asking is - when I collide with water, are these 4 points overlapping the water I collided with.
A potential fix would be to open up all the water instances to be picked again as a sub event, so use System pick all water, then indent again and add your overlap checks for point overlaps water. This will be more in line with what you want I think - when I collide with water, are any of the 4 points overlapping with this or any other water.