I was reading a post today about how to clean a camelbak, or any other similiar bladder.  I bought a Platypus Big Zip years ago and I've never looked back.  At first I had my doubts about using what seemed to be a glorified zip-lock bag, but when you start playing with it you find the zipper really does hold up.  The Big Zip makes it extremely easy to clean the majority of the bladder.  I'm a big guy, but I can put my whole arm in there to clean it.  That doesn't do any good for the hose though.  I've used the CamelBak Cleaning Kit with good results, but the only part of it I still use is the cleaning brushes to get the hose clean.

So, I'd like to make two suggestions when it comes to cleaning a bladder.  First, buy some Polident - it works just as well as the CamelBak cleaning tablets for a fraction of the price.  Second, just put your bladder in the freezer when you are done with it and you won't have to clean it often.  As soon as I get back from a hike, I rinse mine out and put the whole thing in the freezer.  I've been doing this for years without any problems.  You still will need to clean it occasionally but the freeze keeps anything from growing in it.