A basin waste is a fitting that attaches to the outlet of a wash basin and allows for the outlet to be closed to keep water in the basin and opened to drain it. Basin waste fittings range in complexity from simple variants which are opened and closed by a loose plug to sophisticated, pop-up models. All types may be fitted with integral ports or slots allowing for use in basins with or without overflows.

Basin waste fittings are the parts of any wash basin which allow water to be trapped for use and released to drain out. They also serve as a connection point for the waste trap and waste water pipe system. These fittings are connected at the bottom of the basin and are typically flush with the inside surface with a protruding, threaded stub on the outside of the basin to connect the waste water pipe system. A basin waste is basically a hollow tube with a shoulder machined into the end which is located inside the basin. This shoulder allows a removable plug or pop-up mechanism to seat snugly forming a water tight seal.

A pop up waste is a term used to describe the drain plug in the bottom of a tub or lavatory that is opened and closed by a lift rod, trip lever or cable. It is used to handle clogs and blockages in the drainage system or restrict flow.