it has been said some armours have built in canteen, the vault 13 is suppose to be unique in the sense that it′s a item you carry...thus can be used whatever armour you wear.
Built in? Does this lead me to believe armors might actually do more than protect you? o.o Sweet!
OT: I dunno, I haven't heard anything about this really. I have mine pre-ordered from Gamestop, so I'll be getting the canteen and stuff, but I would think that there might be a similar canteen in the Wastes, just not as good as the Vault 13 one.