Hydration Bags. Hydration systems are a great way to keep you hydrated whilst on the go. Hydration bags are compact rucksacks, which allows you to store a few essential items for a day out, and come complete with a water bladder and drinking tube. We stock hydration bags from Camelbak and Platypus. If you already have a rucksack, check out our range of hydration bladders to get your self set with your own drinking system.