It could be apocryphal, and it doesn't help that it seems like something I heard about a long time ago, but as far as I know, when you start to drown the best of your intentions are overcome by your instinct for self preservation. However, Google turns up a result from the Telegraph about a recent case in which someone may indeed have drowned himself in a bucket of water, although there seems to be some confusion over the case. Thanks for calling me on it -- I really am now, in fact, not certain I couldn't.

I couldn't think of a better example at the time, though, so the spirit of the argument will have to stand in for its questionable veracity.