Abstract: The invention is a hydration system that is worn on a user's arm. The system has a flexible sleeve made of an elastic material. A bladder, made of a pliable material, has a number of expandable ribs. The bladder is adhered to the flexible sleeve, the bladder has a generally cylindrical shape. A number of adjustable straps are attached to the bladder. The plastic straps extend around the bladder and are perpendicular to a longitudinal axis of the bladder. A cap is detachably connected to an opening of the bladder. A swivel joint is attached to the cap and provides a fluid passageway between an interior of the bladder and an exterior of the bladder. A flexible drinking straw extends from an exterior end the swivel joint. A tube extends from an interior end of the swivel joint towards an elbow end of the bladder.