Abstract: An on/off control valve for a shower head comprised of a hollow cylindrical unit having an open first end and an open second end. The open first end is adapted for removable coupling with an existing shower line. The unit has a circular chamber formed therein inwardly of the open first end. A by-pass recess is formed within the circular chamber of the unit. A ball valve is rotatably secured within the circular chamber of the unit. The ball valve has a drainage aperture formed through a central portion thereof. The ball valve is rotatable within the circular chamber to a first position with the drainage aperture in alignment with the open first end and the open second end of the unit to facilitate the movement of water therethrough and to a second position whereby the drainage aperture is not in alignment with the open first end and the open second end of the unit thereby inhibiting the movement of water therethrough. A control mechanism is secured to a side portion of the shower head.