Hydration system

It is intended to help its user carry liquid, to support the physical effort involved in the activity, without the need to use one's hands or take off the pack.

The plastic bladders from box wine were repurposed as an inexpensive way to store water when hiking in Australia in the late 1960s but were prone to breakage and leakage.

[2] The concept of the hydration system appeared in Robert A. Heinlein's 1955 novel, Tunnel in the Sky, where the main character has "a belt canteen of flexible synthetic divided into half-liter pockets.

The weight was taken by shoulder straps and a tube ran up the left suspender, ending in a nipple near his mouth, so that he might drink without taking it off."

At least one manufacturer, MSR, offers a in-line ceramic based filter, allowing use of local water supplies for refill.