How to Connect a P-Trap for a Bathroom Sink

A P-trap is a portion of pipe that attaches to the bottom of a sink and curves downward and then upward again before reaching the drain pipe.
This bend creates a “trap” that always contains water. It is this trapped water that prevents sewer gases from rising through the drain at the bottom of the sink basin. P-traps also act as a catch point for small objects, which are inadvertently dropped into the sink. Fortunately, connecting a P-trap to a bathroom sink takes only a few minutes.

Step 1

Wrap the threads of both ends of the P-trap with Teflon tape to prevent leaks.

Step 2

Slide a single slip nut onto the drain pipe that extends from the sink’s wall, followed by a single compression washer. The slip nut must be placed onto the drain pipe with the threads of the nut facing downward.

Step 3

Slide a single slip nut onto the drain pipe that extends from the bottom of the sink basin, followed by a single compression washer. The slip nut must be placed onto the drain pipe with the threads of the nut facing downward.

Step 4

Position the P-trap onto the two drain pipes. The shorter of the P-trap's two openings must be placed against the opening of the drain pipe that extends from the wall of the bathroom, and the P-trap’s longer tube must be placed against the bottom of the sink’s drain pipe.

Step 5

Slide the two compression washers to the end of their drain pipes, then slide the two slip nuts down their drain pipes until they reach the threaded ends of the P-trap.

Step 6

Hand-tighten the two slip nuts onto the P-trap.

Step 7

Tighten each slip nut a quarter turn with channel-type pliers, then turn the sink on and check both fittings for leaks. If leaks are present, tighten the leaky fitting a quarter of a turn at a time with the pliers until the leak stops.

Things You Will Need

  • Teflon tape
  • Two slip nuts
  • Two compression washers
  • Channel-type pliers

About the Author

John Stevens has been a writer for various websites since 2008. He holds an Associate of Science in administration of justice from Riverside Community College, a Bachelor of Arts in criminal justice from California State University, San Bernardino, and a Juris Doctor from Whittier Law School. Stevens is a lawyer and licensed real-estate broker.