A hydration system is an apparatus used in recreation and other sustained outdoor activities. 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.[1] Such systems for consumers were first sold to cyclists, and by the 1990s had also found a substantial market among hikers. Familiar commercial models can also be recognized occasionally worn by western military personnel in southwest Asia.
In practice, such a system is almost always a commercially manufactured unit that features at least
Also common are designs that include specific hands-free means to comfortably carry the hydration system.