A personal hydration system includes a control valve assembly including a valve body provided with a first inlet port fed by a liquid, a second inlet port, and an outlet port for dispensing at least fluid from the first inlet port. The control valve assembly further includes either a flexible and resilient or a non-collapsible reservoir which holds an additive and is mounted to the second inlet port. The first inlet port can be provided with a valve for preventing backflow of the additive from the reservoir, and the reservoir can be provided with a screen for disrupting coagulation of certain additives when mixed with liquid. A valve core is rotatably mounted in the valve body to establish various flow conditions.