identify this movie - Kids in a post-apocalyptic world playing a hockey-like game

I've been trying to remember the name of a movie I saw once, when I was younger - maybe early 1990s. The movie takes place in a post-apocalyptic world. Water is rationed and the world is basically a desert. All the water in the world has been locked up in a building/bunker.

I remember there being some, I think kids, playing a hockey-like game with round balls. One of them finds a new ball the glows or something, in the end it turns out to be a comet.

I know it sounds weird, maybe I made it up and just think I watched it when I was a kid. It may well have been a made-for-TV movie. Anyone remember anything like this that can help describe it better than me? I'm looking for the title of the movie.