Abstract: A waste water outlet unit, for a shower tray having a drain opening, comprises a base element which is locatable on the underside of the shower tray to cover the drain opening, and a clamp element which is locatable on the topside of the shower tray and which is engageable with the base element to clamp the base element to the underside of the shower tray. The clamp element has an aperture through which waste water from the shower tray can pass into the base element, and a filter element which is positionable over the aperture and which can be removed to enable access to the interior of the unit while maintaining the engagement between the base and clamp elements.