I live in a very hot area and have done many centuries and long rides with a Camelback. My MO is to fill it with clean water upon return home and put it in the fridge. (I use the crisper drawer.) Nice and chilled w/o risk of rupture. Done it for years.
If it's gonna be a really long ride, I'll dump a little liquid and replace with ice cubes before I head out. Either way, it stays cool for hours. If I drink it all on the ride, which is normal around here, we stop at a country store and buy a bag of ice and jugs of water to share and refill.
Never tried the freeze method, but never needed to. Never heard a horror story either.