massbikebabe -- the taste just never comes out of the bladder, and eventually it gets gross.

I've also heard that half a denture tablet can be used to clean a 'bak bladder.

I'm lucky -- I live in an extremely dry climate where things don't have the same tendency to grow as they do, say, out East. I only use water in my camelbak and have never had to clean it. Water still tastes fine.