I only use the genuine Camelbak brand because they're the best by far.. IMO
I've used them for mountain bike riding for years and I soon discovered the hassle of cleaning them out..drying them out and trying to stop mold growing in the bladder and straw.
But I know the answer to that problem now... and it's so easy.
I never use plain water.. I always use a light mix of lemon cordial.
I can leave it half full for days.. weeks..and even months.. and then sip away without any risk of mold or any nasty stuff growing inside.
The cordial has preservatives in it and prevents any mold growing.. maybe the sugar does something also.. also.. I use lemon because orange or lime cordial discolors the straw and bladder.
I've not even rinsed a bladder out for years and all my Camelbaks are still perfect.. I think I have about four now.. I bough a new 2ltr Camalbak just before our last down-winder because I knew it was going to be a long one (little did I know).
I might look for a 3ltr one soon.. maybe also a waist (bum bag) style... You can never have too many Camelbaks..

Anyway.. that's my two cents worth..

DJ