A portable toilet chemical additive charging system comprises a restroom cabana containing a toilet bowl which opens into a waste-holding tank. A water source, such as a separate water tank, is connected by a conduit to the toilet bowl for delivering flush water to the bowl when a flush pump, that is connected to the conduit, is actuated. The flush water passes through a control valve in the conduit. A chemical additive container is removably positioned near the toilet bowl and is connected by a tube to the control valve. The control valve injects a pre-determined amount of additive to the flush water when flush water is flowed through the control valve to the bowl. Preferably, the container is shaped to closely fit within a space between a vent pipe extending upwardly from the waste-holding tank and the adjacent interior surface of a wall of the cabana. A portion of the container is substantially transparent and exposed so that an observer may view the level of additive content in the container, while the remainder of the container is substantially concealed by the vent pipe.