You've most likely seen them, in the military or just around town, perhaps at sporting events. A CamelBak is like a backpack that comes in a variety of sizes, most from 1, 2, or 3 Liter capacity. They make water bottles as well, but I am referring to the packs, presently. They have several models available:
http://camelbak.com/en/government-military/hydration-packs.aspxMine is the 3L Thermobak. Good system, haven't had a chance to field test it yet. I got it brand new in a trade for some leather vambraces I made for a military guy. Anyway, these things are useful. They have a bitecap so you don't need to open any bottles or use your hands. Mine has D rings on the front, so it can be worn over another pack or attached to something else, the shoulder straps unclip and fold in a pocket on the underside. The pouch is removable for easier cleaning, but the hanger portion on the top makes it a pain to undo. A good buy, if one desires great hydration. The insulation will keep hot (over boiling) drinks hot, and cold (below freezing) drinks cold. The "omega" mouth of the pouch is rather wide so that a hand can fit inside to clean it, or for mass filling/emptying of the pouch. The claims state that the pouch can be run over by a car and not pop, so it could be filled with hot water and used for warmth or a pillow at night.
What kind of drinks could one put inside this system other than water? So far I was thinking tea.
One
can put drinks such as hot cocoa, gatorade, soda, and the like inside, but the sugar would cause mold quickly unless washed immediately afterward.
Washing is as simple as hot water, some people use vinegar, others use bleach, some use baking soda. I have heard tell about using denture cleaning tablets, but am unconfirmed to that. There is no real need to buy those tablets they sell, nor the cleaning kit.