Hydration Systems Do More Than Tote Water - Water bottles and cages are adequate for carrying drinks. But, hydration systems offer many advantages. For example, they're insulated, which keeps beverages cooler (or warmer) longer and there's a drinking tube that makes sipping much more convenient because your hands remain on the handlebars. Also, the capacity of larger hydration packs is more than double that of two large water bottles. And, the hydration pack provides a place to stash your jacket, food, ID, small tools and more -- you can even attach a taillight!