i use only metal water bottles from SIGG (swiss) and run through the steam autoclave when they get slightly smelly. i understand that not everyone has access to an autoclave, so ...

you can just submerge them in a pot with boiling water at home, although a food-based pressure cooker would be better, if you have one hand (we cook with one all the time).

http://www.amazon.com/WMF-Perfect-2-...ressure+cooker

as far as the camelback goes, it should have a stamp stating what kinda of plastic the lining is made out of (PP, PE, with a number etc...) which will tell you what specifications it can handle (boiling water or pressure cooker/autoclave.)

that should eliminate all microbes.

another option, that i do with my clothing sometimes is to freeze it rather than "washing it" (as it's easier on the fabrics), as that's extremely effective at killing "microbes" as well. that may be an option as well if you don't have access to the stuff listed above.

good luck.