I have heard stories of people drowining in puddles in the bottom of rucks but I can't give you any evidence of it. Usually games are called off if there's too much standing water on the pitch in case something like this happens.

Beating Bill P to the punch: Looks like another Zeppo comment. Basic concept: the game is played on dry land. Which is not to say the pitch doesn't get wet and muddy, but seriously... drown? Mark L.