Sink Strainer

A sink strainer (also called a basket strainer or drain strainer) is the fitting that sits in the sink drain hole, catching food debris and solids while allowing water to drain freely into the P-trap below. It consists of a strainer body (the metal fitting that threads into the drain opening), a removable basket insert (the strainer screen), and a drain stopper or plug for filling the sink. In kitchen sinks, the sink strainer is also the point where the drainpipe begins — it connects to the P-trap through a tailpiece.

Components

• Strainer body: stainless steel or chrome-plated brass; fits into the 3½-inch standard drain opening in the sink. Sealed with plumber's putty under the flange.
• Locknut assembly: a rubber gasket, cardboard washer, and locknut that tighten from below the sink against the basket to clamp the strainer body in place and seal the drain hole.
• Basket insert: the removable perforated screen that catches food — emptied into the trash regularly.
• Tailpiece: a short pipe that connects the strainer body to the P-trap below.

Common issues

• Leak at the drain: the plumber's putty or rubber gasket under the flange has dried out or failed. Resetting the strainer with fresh plumber's putty fixes most leaks.
• Corroded strainer: chrome-plated zinc strainers corrode faster than stainless steel. Replace with a stainless steel model for longer life ($15–$40).
• Clog at the basket: food debris overflows when the basket isn't emptied — clean before the basket is fully packed to avoid forcing debris into the drain.

With garbage disposal

Sinks with a garbage disposal use a disposal flange rather than a strainer — a mounting assembly that attaches the disposal unit to the drain opening. The standard drain hole size (3½ inches) accepts both strainer bodies and disposal mounting flanges interchangeably.