Abstract: There is provided a vortex-valve which comprises a housing defining a vortex chamber, a housing having an inlet through which liquid may enter the vortex chamber in manner to promote swirl within the vortex chamber and an outlet at one axial end of the vortex chamber. A wall of the housing is provided with an opening which is normally closed by a closure, this closure being operable between the closed position and an open position in which liquid may enter the vortex chamber by-passing the inlet. The vortex-valve may be provided at the outlet of a gully and is useful in enabling a blockage, which may occur at the inlet of the vortex-valve, to be by-passed, thereby draining any accumulated liquid in the gully. The blockage may then be removed when the gully is relatively dry.