Some backpacks have a special compartment for a water bag or hydration system. With a water bag, you can easily take water with you when walking or exercising. This way, you always stay hydrated. In addition to the regular water bags, accessories are also available. For example, you can keep the water in your backpack warm or cool with a thermo bag for drinking systems. If your backpack has room for a hydration system, you can find the one that suits you best here.