Hydration packs are designed to provide a sufficient amount of liquid to sustain physical exertion involved in an activity. Hydration packs were first used by cyclists only, but are now a familiar feature with hikers, military people and other individuals involved in recreational activities. A hydration system is built into a pack, which is most often a backpack or waist pack (fanny pack). It is a reservoir (bladder) of liquids, which is carried and consumed "hands free." The liquids are drank through a hose that is connected to the reservoir. The liquids are held in the hose most often with a valve known as a "bite valve." This valve is released when a person applies pressure (bites down) on it.