Some use vinegar, some just use soap and water, I like bleach for cleaning. The key to storing your camelbak after use is you have to ensure it is completely dry when storing it.
I have a link here on how to use bleach to clean water before drinking: http://www.thinklikeahorse.org/images3/bleach%20use.jpg
http://www.thinklikeahorse.org/All_About_Guns.html