I've had Platypus bottles develop tiny leaks after they are several years old. These leaks were not a problem in terms of losing any more than a tablespoon of water, but rather they created problems by getting stuff damp inside my pack.

I have no useful experience with soda bottles in the backcountry, but I have watched them be severely abused, by hurling full bottles high into the air and letting them drop on pavement, without bursting.