http://mountfranklinwater.com.au/our-pr ... asy-crush/
They have started getting these at work as we drink a lot of bottled water on the rig I work on so they are trying to keep the plastic waste down.
They got me thinking they would be good to take walking. You can crush them and easily blow them up again to be filled when needed. For trips where water has be carried in dry areas they would make a great alternative to bladders for those who prefer bottles. Cheap too.
I tried crushing them and then inflating them over and over and they won't leak.
I am not sure about the plastic breaking down after a while but at the price they could be thrown in the recycling away after every trip if worried about this.
Maybe people already use them and I am behind?