Idea for an Emergency 20l Pocket Sized, Fully Bendable Water Container.

While making my survival kit I realized that I needed a water container, but as it is supposed to be small, a small water container is no good becouse it takes almost no water, but a big one is just to big, so I had a click on my brain and decided to use a wine's box's plastic wine container, becouse it is flexable, has a tap, takes plently of water and it's made to keep drinks conserved inside, avoiding the water to spoil.
To use it just wash it very well (you don't want to get drunk while lost), remove all the air and fold it. When you need to fill it, turn the tap upside down and open it, put it under the water you want to put inside and when you're done just close the tap.