Air gapA small fixture by the faucet that the dishwasher drains through. It stops drain water from the sink backing up into the dishwasher.
Bowls (basins)The bowl-shaped basins that hold the water; this sink has two.
Garbage disposalAn electric unit under the drain. It shreds food waste small enough to go down the pipes.
P-trapA U-bend that always holds some water. The water stops sewer gases coming up the drain.
On the counter 3
SprayerA spray for faster rinsing. Here, a separate hand sprayer on a hose.
Soap dispenserA pump built into the sink deck for dish soap.
CountertopThe counter the sink is installed in.
The bowls 1
Basket strainerSits in each drain opening and catches scraps. Many can also close the drain.
Under the sink 2
Dishwasher drain hoseFeeds the air gap's top from the dishwasher. The air gap's outlet runs down into the disposal.
Drain pipeThe pipes that take used water to the wall. It comes from both bowls and the disposal.
How this list was compiled: Read 2026-09-27. (1) Wikipedia, Sink, https://en.wikipedia.org/wiki/Sink : a bowl-shaped fixture with a tap (faucet) for hot and cold water, often a spray for faster rinsing, and a drain that may include a strainer, a shut-off and an overflow; sinks may have an integrated soap dispenser, and many kitchen sinks are installed in a counter. (2) Wikipedia, Trap (plumbing), https://en.wikipedia.org/wiki/Trap_(plumbing) : a trap holds water to stop sewer gases coming into buildings while waste passes; in the United States they are called P-traps, from the U-bend with an elbow and horizontal run on its outlet side. (3) Wikipedia, Garbage disposal unit, https://en.wikipedia.org/wiki/Garbage_disposal_unit : an electric unit under a sink between the drain and the trap that shreds food waste into small pieces. (4) Wikipedia, Air gap (plumbing), https://en.wikipedia.org/wiki/Air_gap_(plumbing) : the dishwasher air gap is a small cylindrical fixture above the sink near the faucet; under the sink the dishwasher's drain hose feeds its top, and its bottom is plumbed to the sink drain below the basket, or to the garbage disposal; it stops drain water backing up into the dishwasher. Licence: own work
The drawing: Drawn for this site by script, 2026-09-27. Own work, nothing traced. Licence: own work
How it works
The parts of a double-bowl kitchen sink, from the fittings on the counter to the plumbing in the cabinet under it. Start with the 5 main parts, then the counter, the bowls and under the sink.
Read the full guide
On the counter
The faucet supplies hot and cold water, with a sprayer for rinsing and a soap dispenser beside it. The small cap is the dishwasher's air gap: the dishwasher drains through it so sink water cannot back up into the dishwasher.
Under the sink
Each bowl drains through a basket strainer. The left one feeds the garbage disposal, which shreds food waste; the dishwasher hose drains into it too. Both drains meet over the P-trap, whose water seal keeps sewer gas out.
The U-bend under the sink is meant to stay full of water: that water is what keeps sewer gas out.
Questions and answers
What is the thing on the counter by the faucet?
Usually the dishwasher air gap, a small cap the dishwasher drains through, or a soap dispenser. The air gap stops sink water backing up into the dishwasher.
What is the U-shaped pipe under a kitchen sink called?
The P-trap. Its bend always holds a little water, which stops sewer gases coming up the drain into the kitchen.
Where does the dishwasher drain under a kitchen sink?
Its hose runs up to the air gap on the counter, and the air gap's outlet runs down into the garbage disposal or the sink drain.