Wow. I'm not nearly smart enough to do the math on that, but I estimate that a waterbomb dropped from space, directly onto Suzie's head, would probably implode the universe.
Afraid your waterbomb would never make it - the only reason the paper plane can get through without all that incovenient "fiery destruction" is because it's lower weight and speed mean it doesn't experience as much friction at a rather sedate mach 7. Your unaerodynamic waterbomb would get closer to the face-blistering mach 22 of normal re-entry - or at least it would approach it before evaporating into the atmosphere.