The only issue I've come across putting the water bladder at the top of the pack is wetness - sometimes from condensation, sometimes from being laid in an wet area and nothing to dry it off on (maybe rain) and once I didn't have the lid on quite right. I now have a connection on the actual hose that attaches to my bladder so I don't open it at all, so I'm pretty happy. My new back pack does have a pouch along the back for my bladder, and I haven't had much issue pulling it out and slipping it back in full - though with the filter attachment I don't have to pull it out of the pack it all (other than it is easier to see if the bladder is full.)