Well, in today's legalistic society, it ought to be illegal to have water-drinking contests of any sort. I mean, there are so many other kinds of contests. I don't see anything wrong with the idea of having contests, in general. Competing is optional.
An endurance contest that is better is the one like where you have to put your hand on a car and keep it there, last person standing without removing their hand wins! Stuff like that. With a medical professional supervising.
And of course there's always trivia!