Link seems to be broken (read about it here), but here's a working version.
My entry for the TF2Maps 72hr Summer Jam!
Have you ever wanted to go to a (presumably) water-pump facility and play footballhockeybasketball in it? Do you like playing cat-and-mouse with containers and with a full team of mercenaries? If so, Watercontainer is for you! Don't mind the sightlines.
I got the soundscape prefabs from the Ultimate Mapping Resource Pack, so thanks Boojum Snark!
Pictures (windows are black because of func_areaportalwindow, don't mind them):