I think REI has the Platypus canteens. There's probably an REI near you. I had the 1L version a while back and IIRC it sprung a leak. They're certainly more durable than ziploc bags, but much bulkier too. I'd say you can't really put one in a typical pocket kit. I guess they could be handy in a larger kit but at that point I'd go for the 2L version or an even larger one. Nalgene also makes some canteens like that, up to 3 liters. See rei.com for a wide selection.

Didn't Cody Lundin in 98.6 have a bit on that?

For rubbers [sorry] you would just have to fill them gradually, allowing the water to expand them before adding more. Dind of a sip more than a swallow concept.

Hello, is this thing on... Okay.

Mylar balloons folks. They are the perfect membrane, relatively easy to fill, just like a bag, no elasticity, just pure volume, small go hole so easy to pour. I have yet to have one fail on me before it's usefulness was exhausted. Can be rolled or folded into very small dimensions. Usually comes with a cool picture or slogan on the outside. <img src="/images/graemlins/grin.gif" alt="" />

And the graphic may make you smile. Good one Ben.