Short definition
A tailpiece is the straight vertical drain pipe between a sink and its P-trap. It hangs from the basket strainer (kitchen) or the pop-up body (bathroom) and slip-joints into the trap below. Standard sizes are 1¼-inch for lavatories and 1½-inch for kitchen, laundry, and tub. Tailpieces are slip-jointed at both ends so they come apart by hand for cleaning or replacement.
What it is
Look under any sink. The straight tube of plastic or chrome-brass dropping out of the bottom of the sink drain is the tailpiece. It connects the sink’s drain assembly above to the P-trap below, with slip-joint nuts at both ends. Standard length is 6 to 12 inches, and longer extensions are sold for sinks that drain to a trap mounted further down.
A few specialty variants exist:
- Standard tailpiece — straight tube, slip-joint each end.
- Flanged tailpiece — flange at the top seals into the basket strainer or pop-up body.
- Tailpiece extension — additional straight tube to lengthen reach.
- Dishwasher tailpiece — kitchen tailpiece with a side nipple to accept a dishwasher discharge hose. Used on sinks without a disposer.
- Disposer discharge tube — a short factory tailpiece on the disposer side of a double-bowl sink.
When the trap and the sink drain don’t line up — a common situation when retrofitting a new sink onto an old wall stub-out — a flexible-extension tailpiece or an angled offset tailpiece bridges the gap without forcing the connection.
Why it matters to a homeowner
The tailpiece is the first piece to come off when you’re working on under-sink drainage. Pulling it out lets you clear a trap clog, replace a leaky pop-up, or swap a corroded chrome-brass kit for a clean plastic one. It’s a $5 part at any hardware store, and the hardest thing about replacing one is making sure you grab the right diameter:
- Lavatory tailpiece = 1¼ inch.
- Kitchen tailpiece = 1½ inch.
- A reducing washer ($1 part) adapts a 1¼-inch tailpiece to a 1½-inch trap when you’re retrofitting an older lavatory drain into a wider trap.
If a sink doesn’t have a disposer and you’re adding a dishwasher, the dishwasher hose connects through a special dishwasher tailpiece with a side nipple — different from a plain tailpiece, sold for about $8.
Common failure modes
- Slip-joint leak at the strainer end — washer or threads at the top connection. Tighten gently or replace the washer.
- Slip-joint leak at the trap end — same fix at the bottom connection.
- Cracked plastic tailpiece from over-torqued slip nuts. Cut it out and replace.
- Corroded chrome-brass pinhole — replace with plastic.
- Tailpiece too short or too long for trap alignment — use a flex or extension; never force the connection.
Common variants and what a tailpiece is not
- Tailpiece vs. trap arm. Tailpiece is the vertical drop from the sink to the trap. Trap arm is the horizontal run from the trap outlet to the wall stub-out. Both use slip joints; they’re different pieces.
- Tailpiece vs. supply tube. Supply is the small flexible line (¼ to ½ inch) bringing water to the faucet. Tailpiece is the larger drain line (1¼ or 1½ inch) carrying water away from the sink.
- Dishwasher tailpiece vs. disposer side port. Dishwasher tailpiece is for a sink with no disposer. With a disposer, the dishwasher hose connects to the disposer’s side knockout port instead.