Install P-Trap — Connect P-Trap to Wall Drain
Part of project
How to Install a Bathroom Sink Drain and P-Trap · Step 5 of 6
In this video
Install the P-trap. Dry fit the pieces first to get the correct height and alignment. Cut a vertical piece of pipe to connect the horizontal drain assembly down to the P-trap inlet. Ensure there is a minimum of two times the pipe diameter (e.g., 3 inches for 1.5-inch pipe) of straight pipe between the P-trap outlet and the TY fitting to prevent siphoning. Once measured, glue the P-trap into the TY fitting. Connect the union joint and tighten by hand, using channel-lock pliers for a final snug turn if needed.
Goal: Connect the horizontal drain to the vertical stack and prevent sewer gas from entering
- Per plumbing code, ensure there is a straight pipe section of at least two times the pipe diameter between the P-trap and the vent tee (TY).
- Hand-tighten the union nuts on the P-trap and trap adapters first. Use pliers only for a slight final tightening to avoid over-tightening and cracking the plastic.
Used in this video
- Tape Measure (Tool Type: Measuring Tool, Measuring Tool Type: Tape measure) — Measuring the length of the vertical pipe section.
- Channel-Lock Pliers (Tool Type: Pliers, Pliers_Type: Channel-Lock) · optional — Providing a final snug tightening on the P-trap and trap adapter nuts.
601K subscribers
FAQs
Is this 'beginner' difficulty truly accurate, and can I realistically complete it in 3 hours if I'm new to plumbing?
Yes, this project is considered beginner-friendly as it doesn't require complex pipe cutting or soldering. The 3-hour estimate is achievable for most DIYers, but gathering all tools and materials beforehand and reviewing the steps thoroughly will help minimize delays. If your existing drain components are heavily corroded, removal might extend the overall time slightly.
What's the most common reason for leaks after installing a new drain and P-trap, and how can I prevent them?
The most common cause of leaks is insufficiently tightened connections or improperly sealed joints. Ensure all slip nuts are hand-tightened firmly, then give them an extra quarter to half-turn with channel lock pliers, being careful not to overtighten and crack plastic components. Always apply a consistent, generous bead of plumber's putty under the drain flange to create a watertight seal against the sink basin.
The guide mentions plumber's putty; can I use silicone sealant instead for the drain flange?
While silicone sealant can provide a durable seal, plumber's putty is often preferred for drain flanges because it remains pliable, making future disassembly much easier if needed. If you choose silicone, ensure it's 100% silicone specifically rated for bathroom/kitchen use and allow adequate curing time before running water. Plumber's putty typically offers an immediate, reliable seal.
What should I do if the old drain assembly is seized or difficult to remove from the sink?
Old drains can be stubborn due to corrosion or mineral buildup. First, try applying penetrating oil to the threads of the locknut under the sink and let it sit for a few minutes. Use your channel lock pliers for maximum leverage, turning slowly but firmly. If it's completely stuck, you may need to carefully cut the old drain pipe components below the sink with a mini hacksaw to free the drain body, being careful not to damage the sink itself.
Install P-Trap — Connect P-Trap to Wall Drain
Part of project
How to Install a Bathroom Sink Drain and P-Trap · Step 5 of 6
In this video
Install the P-trap. Dry fit the pieces first to get the correct height and alignment. Cut a vertical piece of pipe to connect the horizontal drain assembly down to the P-trap inlet. Ensure there is a minimum of two times the pipe diameter (e.g., 3 inches for 1.5-inch pipe) of straight pipe between the P-trap outlet and the TY fitting to prevent siphoning. Once measured, glue the P-trap into the TY fitting. Connect the union joint and tighten by hand, using channel-lock pliers for a final snug turn if needed.
Goal: Connect the horizontal drain to the vertical stack and prevent sewer gas from entering
- Per plumbing code, ensure there is a straight pipe section of at least two times the pipe diameter between the P-trap and the vent tee (TY).
- Hand-tighten the union nuts on the P-trap and trap adapters first. Use pliers only for a slight final tightening to avoid over-tightening and cracking the plastic.
Used in this video
- Tape Measure (Tool Type: Measuring Tool, Measuring Tool Type: Tape measure) — Measuring the length of the vertical pipe section.
- Channel-Lock Pliers (Tool Type: Pliers, Pliers_Type: Channel-Lock) · optional — Providing a final snug tightening on the P-trap and trap adapter nuts.
Frequently Asked Questions
Is this 'beginner' difficulty truly accurate, and can I realistically complete it in 3 hours if I'm new to plumbing?
Yes, this project is considered beginner-friendly as it doesn't require complex pipe cutting or soldering. The 3-hour estimate is achievable for most DIYers, but gathering all tools and materials beforehand and reviewing the steps thoroughly will help minimize delays. If your existing drain components are heavily corroded, removal might extend the overall time slightly.
What's the most common reason for leaks after installing a new drain and P-trap, and how can I prevent them?
The most common cause of leaks is insufficiently tightened connections or improperly sealed joints. Ensure all slip nuts are hand-tightened firmly, then give them an extra quarter to half-turn with channel lock pliers, being careful not to overtighten and crack plastic components. Always apply a consistent, generous bead of plumber's putty under the drain flange to create a watertight seal against the sink basin.
The guide mentions plumber's putty; can I use silicone sealant instead for the drain flange?
While silicone sealant can provide a durable seal, plumber's putty is often preferred for drain flanges because it remains pliable, making future disassembly much easier if needed. If you choose silicone, ensure it's 100% silicone specifically rated for bathroom/kitchen use and allow adequate curing time before running water. Plumber's putty typically offers an immediate, reliable seal.
What should I do if the old drain assembly is seized or difficult to remove from the sink?
Old drains can be stubborn due to corrosion or mineral buildup. First, try applying penetrating oil to the threads of the locknut under the sink and let it sit for a few minutes. Use your channel lock pliers for maximum leverage, turning slowly but firmly. If it's completely stuck, you may need to carefully cut the old drain pipe components below the sink with a mini hacksaw to free the drain body, being careful not to damage the sink itself.