Eberlestock Hydration System 3 Liter - $40 - Designed to fit the hydration sleeve of nearly every Eberlestock backpack, these hydration bladders are essential for long, sustained marches where you don't have time for a water break. Smart design powers these Eberlestock hydration pouches; a Storm Valve makes drinking easier, the bladder itself is BPA-free and features anti-bacterial components. You can fill the Eberlestock 3 Liter Water Bladder from a stream using the wide mouth.