A trap adapter is a fitting that connects compatible tubular trap tubing to the drainage piping beyond it. A common plastic DWV version has a tubular slip-joint connection on one side and a specified socket or spigot connection on the other. It adapts connection systems; it does not replace the trap or create the trap's water seal.
A trap adapter is a fitting that connects compatible tubular trap tubing to the drainage piping beyond it. A common plastic DWV version has a tubular slip-joint connection on one side and a specified socket or spigot connection on the other. It adapts connection systems; it does not replace the trap or create the trap's water seal.
Identify both ends of the fitting
Under a sink, the trap's wall tube approaches the drain opening toward the wall. The adapter is the transition at that connection. One side accepts the specified tubular tube, nut and sealing washer. The other side belongs to the identified drainage, waste and vent pipe system.
Charlotte Pipe's DWV catalog labels several male trap adapters as DWV spigot by tubular slip. It lists different supplied nuts and washers for particular versions. Oatey's P-trap guide separately identifies the wall or trap-adapter connection as one point in the drain assembly.
Those descriptions do not mean every adapter has the same DWV end. Read the actual end label and product drawing. A spigot is intended for a compatible socket; an adapter with a socket receives the matching pipe or component. A threaded version, if specified, has a different joining method again.
A size label needs the connection family
Tubular drain products and nominal DWV pipe are different product systems. The adapter bridges specified parts from those systems, so measuring one opening or matching two package fractions is insufficient.
Some cataloged adapters include a washer combination for a smaller tubular tube. That is a defined component arrangement, not permission to use a random reducing washer with any nut or body. Our slip-joint washer entry covers those sealing-ring differences.
The DWV connection and the tubular connection also need their own assembly instructions. The presence of one solvent-welded joint does not make the removable washer joint suitable for glue. Conversely, a slip nut does not establish how the concealed DWV end was joined. Product material and the specified connection method must agree on each side.
Questions at a leaking wall connection
Ask the installer to identify the tube size and material, adapter model or end configuration, and condition of the connected DWV pipe. A drip near the wall can involve the washer, tube, adapter or piping behind it; the location alone does not prove which part failed.
The tube should meet the connection without forcing the trap into an unsuitable shape. A cracked adapter or inaccessible damaged pipe may require a different repair scope from replacing an exposed sealing ring.
Our P-trap explanation covers the retained water and venting function. Tubular drain pipe explains the removable product system. The adapter connects that system to its specified drainage connection without changing those other requirements.