No heat transfer from the body in any of my setups. However, the first few sips from the hose after a time are warm due to the sun heating up the water exposed in the hose. Once past those initial two sips, my water is plenty cool for me, even after a long hike in the heat. I don't pack ice in the bladder, but you certainly could. Most bladders have a wide mouth (Nalgene bottle threads, usually).

You can even get insulated tubing covers for the exposed tubing. They also make an insulated cover for the bladder itself just in case you are expecting to go into a VERY hot environment...it'll keep it cooler longer.

>> the first few sips from the hose after a time are warm due to the sun heating up the water exposed in the hose <<

I put the insulated hose on mine shortly after buying it and would not go back to uninsulated. I also prefer the cover on the bite valve that comes with the hose conversion - I never have a mucky or dirty bite valve.

It's worth the $16 to me; ymmv. The bite valve cover is available seperately for less money.

I like the 100oz (3 liter) Camelback system so much that I purchased the bladder/insulated cover kit to stow in whichever of my backpacks I'm carrying when my day pack (Camelback Rim Runner) is not big enough for the outing. Then I added the insulated hose kit to THAT as well...

I still carry at least one polycarbonate Nalgene bottle or a US Canteen, but the first time I used my hydration pack, I was CONVERTED. 'Nuff said.

I'll have to play with mine some more. It is insulated. The tubing comes from the pack body down the inside of an insulated packstrap (never going outside), and then the tubing has an additional insulating sleeve around it to boot. It's made to be insulated from freezing, but insulation is insulation. I do not have that inner insulating sleeve slid all the way down to the bite valve, and maybe it's that last 5 or so inches of exposed tubing that's warming up on me. I'll try sliding that down. Alternately, I could pull the hose up so that only the bite valve sticks out of the packstrap, but then I might look funny turning my head to the side and sucking water from my armpit area! A little bit of tubing hanging out makes sipping more practical.

My other pack has an uninsulated setup where the tubing comes out near the packstrap attachment, and then follows the strap on the outside. I haven't noticed that setup getting any warmer than my other setup. It's only the first two sips, so the minor amount of warming is not a critical issue.

I put mine on with cold weather in mind... so the first place I went with it was the SW desert areas of the US in early July... I can tell quite a difference in first-sip water difference between mine and my wife's identical setup without the insulated hose (she does not like the cover on the hose for reasons of her own). You are correct that it is not as cool as the water in the reservoir. OTOH, I prefer my water to NOT be icy cold in those conditions - hits the palate and stomach hard on me if it's icy cold. Mostly personal preference, I suppose.

Winter treking made me a belt and suspenders man, so after slaking my thirst in sub-freezing temps, I blow the water out of the tube and back into the reservoir. If the warmer temp water in the hose ever bothered anyone, I suppose that could be done in hot weather as well. I try to NOT blow any air into the reservoir itself, as one of the features I like about a bladder is it makes zero <slosh> noise as long as there is no air in the bladder. Much quieter than a 1/2 empty water bottle. After a little practice, it's pretty easy to gauge how much breath to expel to push the water back without blowing a bubble.

The no-slosh is so great that any auxiliary water bottles I carry are either full or emptied into the bladder. I like things fairly quiet when I'm wandering in the woods.

Tom

Now THERE's an idea! So long as it can be controlled so that you don't blow so much as to fill your bladder with slobbery 'ol mouth germs (not to mention sloshy air bubbles). I'll surely try this.

On your other point, if it's so cold that water is freezing in my hydration bladder ... well, you won't find ME out hiking! I'm getting too old for that. More likely you'll find me curled up with a cup of tea in front of some episode of Lost on the TV. Yes, I know it's not an accurate survival show (Sayid washing his hair in the group water supply? Yeuch!) But still a fun show to watch anyway.

Now why didn't I think of that. I've been freezing my tube & mouthpiece and doing without water since starting to xcountry ski with my hydra pack. Gonna try that the minute I get home !!!