Rather than use a water bladder system I just attach a Smartube to some Tatonka Stainless Steel water bottles held in side pockets of my day pack. Sigg Neoprene Covers for the bottles help with the friction holding them in the side pockets reasonably securely. The stainless internal steel walls of the bottle also help with the sterilisation of the water when giving the water a blast with a Steripen.

http://www.bluedesert.co.il/