Originally Posted by
toast2266
I run mine with a 2.5 L bladder (+ a bottle on the frame, if needed). Works fine, and I think it'd still be good with 3L. It's much more stable than a regular fanny pack because of the shoulder straps.
There's definitely not as much space in there as a full size pack, but you can fit a fair amount of extra stuff. I'd often carry the full bladder, a small pump, a shock pump, a tube, tool, and a bunch of food. If you want to carry a bulky jacket or anything like that, it probably needs to get strapped to the outside.