Most athletes have a dilemma at the outset of their physical activities: how best to stay hydrated during competition or training. The water bottle was the only option for a long time, but water bottles could be difficult to carry and store; cyclists often lost the water bottles to rough terrain and bumps. Hikers would have to take off their backpacks to dig out the water bottle, costing them time and effort. To counter this problem, hydration packs were developed. Hydration packs are small to medium sized backpacks that contain a plastic bladder that can be filled with water. The bottom of the bladder is connected to a hose that can be slung over the shoulder, and a bit valve is fixed to the end so the user can drink water without removing the pack.
Perhaps the most well known hydration packs feature the Camelbak® logo, but they were not the first makers of hydration packs. Much simpler versions came first, some without hoses and some without actual backpacks. Early versions were simply bladders that could be stored more easily into a backpack. Then came hydration packs with shoulder straps for carrying during exercise, featuring the hose. The evolution of the bite valve came next, as early versions were prone to leaking. Some bite valves now come with a built-in shut-off feature so the valve does not leak when the pack is not in use.
The plastic bladders inside hydration packs are prone to mold, which means thorough cleaning is often necessary to keep the pack usable. While some hydration packs featured bladders that were prone to bursting or leakage, most bladders are now resistant to such damage, as the materials used are more durable and well constructed. Many athletes choose to put sports drinks in the hydration pack bladder, which can leave an aftertaste if water is then used in the pack. Thorough cleaning is necessary to get rid of the taste of sports drinks or other liquids.
The evolution of the pack itself is quite notable. Early designs featured only a sheath or sleeve to hold the bladder, but over the years, new pack designs featured storage for anything from car keys to spare bicycle tubes, from a light jacket to items as large as a sleeping pad. A hydration pack has become an essential tool for mountain bikers doing longer rides, hikers who need storage and easy access to water, and other athletes who need to hydrate frequently without the hassle of stopping the exercise to dig for a water bottle.