Not everyone in the world has can easily access clean drinking water and the WaterWear backpack was designed to help people in developing countries to transport their liquid from place to place.
Typically, women and children would be sent on the long journey to fetch water from a far-off location and then be required to cart it back to their homes in whatever bucket or container they could find. These heavy containers of water would usually be carried on their heads or backs causing immense strain on one's joints -- not to mention the possibility that the container used to carry the water may have once been filled with dangerous chemicals that could easily contaminate the drinking water.
This sack from Greif and Impact Economics was designed to eliminate these problems and can carry up to 20 liters of water at a time. It is made from a durable, yet lightweight, material that evenly distributes the weight of the water and can be folded down flat when not in use.