What water reservoir do you recommend?

The Platypus carries fine, is light and durable. My personal favorite.

I love my osprey reservoir and kinda wish there was a lighter version that held its shape so you dont get bladder bulge in the backpanel. Anyone know a good way to reduce this in a frameless or nearly frameless pack. Or anyone modified a platybladder to give it some structure like the osprey ones?

Alex, what Osprey reservoir do you have? The only frame in my pack is a thin piece of foam, and the Platypus seems that it would cause a bulge.

I save weight by ditching the hose. I use simple 2L Platypus bottles, one on each side of my pack for balance.

The platypus bottles and tube are light and hold up very well. Do you plan on carrying your water on the inside or outside of your pack?

Interesting idea (see http://www.ospreypacks.com/en/product/hydration_packs__osprey_hydraulics/hydraulics_2_liter_reservoir).

Gerber had a rigid reservoir that I thought would make a good frame for an UL pack, getting double use for the weight.

I have one of the original 3L ones. The new version is lighter, although i dont know the weights of either. I use it in my frameless flash 18 day pack and it makes it very comfy.

I was thinking maybe a piece of milk carton glued onto the out side of the platy might give structure to the lighter reservoir

I found some plastic cutting boards sold by Vitamix that are 0.05"/1.28mm thick. An 18"x12" sheet weighs 5 ounces. It is far stiffer than an milk carton side and I don't think it would do much to resist the bending forces from a full 2L or 3L bladder, let alone the milk carton. The other problem would be to get it bonded– these plastics peel off most adhesives. Some double-stick tape might work.

If the bump is a problem, it will settle down after the first half liter or so has been used anyway. I think adding adding a stiffener would just add weight to no avail.

I like bottles in side pockets better for several reasons.

I used Smart Water bottles in my side pockets on my last trip, but with my particular pack it's difficult to get the bottles back in the side pockets after drinking and I'd always have to ask my hiking buddies. I'm interested in trying carrying bottles on my pack straps, but I'm not sure exactly how that mod works. Anyone care to enlighten me? Thanks

As for the mod, you can get something like a Wet Rib.

http://www.mysteryranch.com/hunting/hunting-pack-accessories/wet-rib

There are lighter versions, but I don't know who's still making them. I can't take advantage of them because I've always got a DSLR strapped to my shoulder straps…

You can use a gizmo called a Smartube, that allows you to attach a hose to a water bottler or Nalgene in your side pocket.

1-liter Avian bottles. Free at the recycling center. I wish I stocked up back when they made wide-mouth bottles. Especially for caving. In which fluid hauling is bidirectional. Enough said. Or perhaps too much. So now, reluctantly, one Gatoraide bottle is in the mix.

+1 on Smart Tube.
I got one about 2 months back and love it. Use with any bottle that a Sawyer Squeeze attaches to.
Right now I use it with a Fuji 1.5L bottle and it works nicely.
Use it with 2L soda bottles, just pick up the size you need for the trip.

Look into the WLP water bladders at sourceoutdoor.com. The weight is 200 grams for the 2 liter but they are advertised to hold their flat shape when filled.
Happy Gear-Hunting!

What I do is use a larger bladder and just partially fill it. That way it maintains a slimmer profile when its in its sleeve. It works ok. I really haven't found ballooning of the bladder to be much of an issue though. I use a 3L platy and usually fill it up to about 1-1.5L.

Another thought is to somehow heat seal a vertical seam down the middle of the bladder (not all the way to the top and bottom). This would prevent the ballooning effect. I've read that a food vacuum sealer will reseal soft bottles and bladders, but it would be difficult if not impossible to get one to seal the bladder in the proper place. Any thoughts on what else might work to do this?

del

A couple of 1.25 L PET rocket-base bottles are usually lighter, and (being free) a lot cheaper.

If I really need to haul a lot of water, I use an empty 4 L wine cask bladder or an empty 4-6 L OJ cask bladder. Tough, light, good seal, and free too.