Tailpiece — Vertical Drain Pipe Connecting Sink to P-Trap

A tailpiece is the straight vertical pipe section that connects the drain outlet of a sink or lavatory fixture to the P-trap below, channeling wastewater from the drain opening into the trap.

Tailpiece (Drain Tailpiece) diagram — labeled parts, dimensions, and installation context

What It Is

The tailpiece is the first section of drain pipe below the sink strainer or pop-up drain body. It threads or slip-fits into the drain flange at the top and connects to the inlet of the P-trap at the bottom. Its primary job is to bridge the gap between the fixture drain and the trap, which is usually set a few inches below the sink bottom.

Tailpieces are made from thin-wall tubing — thinner than DWV pipe — because they carry wastewater by gravity rather than under pressure. The slip-joint connections at both ends are held by threaded slip nuts, which allow adjustment and disassembly without tools beyond hand tightening.

Types

Tailpieces come in 1-1/4-inch diameter for bathroom sinks and 1-1/2-inch for kitchen sinks. Standard length is 6 to 8 inches, with longer adjustable versions available. Materials include chrome-plated brass for visible installations, white PVC, and ABS. Basket strainer tailpieces for kitchen sinks are a variation that includes the strainer body.

Where It Is Used

Tailpieces are found under virtually every sink — bathroom lavatories, kitchen sinks, utility sinks, and bar sinks. They sit between the drain flange and the P-trap in the cabinet below the fixture.

How to Identify One

Look under the sink for the first short pipe section hanging directly below the drain opening. It runs straight down from the drain body to where it enters the trap. The slip nuts on each end are typically plastic or chromed brass and can be turned by hand.

Replacement

Replace a tailpiece when it corrodes, cracks, or develops a persistent leak at a slip joint that cannot be cured by tightening or replacing the washer. Replacement is a straightforward DIY task — loosen the slip nuts, pull out the old piece, and install the new one with fresh slip-joint washers. No permit is required.

Tailpiece (Drain Tailpiece) — FAQ

Why is water leaking from the slip joint on my tailpiece?

The most common cause is a worn or incorrectly seated slip-joint washer. Remove the slip nut, inspect the washer, and replace it if it is flat, cracked, or misshapen. The beveled side of the washer faces toward the fitting.

What size tailpiece do I need?

Bathroom lavatory drains typically use a 1-1/4-inch tailpiece. Kitchen sink drains use 1-1/2-inch. Measure the existing pipe or check the size of your drain strainer or pop-up drain body to confirm.

Can I cut a tailpiece to fit?

Yes. Metal tailpieces can be cut with a hacksaw and the cut end deburred. Measure the distance between the drain outlet and the P-trap inlet to determine the correct length before cutting.

Does the tailpiece need to be plumb?

It should be as close to plumb as possible for proper drainage and to keep the slip-joint washer seated correctly. Significant off-angle connections create chronic leak points.

Is it okay to use a plastic tailpiece?

Yes, PVC and ABS tailpieces are acceptable in concealed locations under a sink. Chrome brass is preferred when the drain is visible, such as under a pedestal sink or in a bathroom without a vanity cabinet.