How to Remove and Replace a P-Trap Under the Sink

P-traps fail in two ways: they leak, or they clog and back up. Both are fixable by removing the old trap and sliding a new one into place. This is the job that teaches you plumbing doesn't require a license—just patience and a willingness to work in a tight space. A P-trap is the U-shaped pipe under your sink that holds water to block sewer gases and catches whatever falls down the drain. When it leaks, the water pools under your cabinet. When it clogs, your sink drains slowly or backs up. Either way, replacement is straightforward: the trap connects to the sink tailpiece above and the wall drain below using nothing but two slip nuts. You don't need soldering, special tools, or any real skill. You do need a bucket, an adjustable wrench, and about 30 minutes.

1. Kill the Water First. Locate the shutoff valves under the sink—there should be one on the hot and one on the cold line. Turn both handles clockwise until they stop. If there are no valves, go to your main water shutoff (usually in the basement, garage, or outside) and turn it off. Open the faucet briefly to confirm water has stopped flowing.
2. Catch the Spill. Place a bucket or shallow pan directly under the P-trap. There will be standing water in the bend of the trap, and it will spill when you loosen the connections. A bucket catching that water is the difference between a clean job and a wet cabinet.
3. Loosen Top Connection. Look where the sink's drain tailpiece (the vertical pipe coming down from the sink) meets the top of the P-trap. There's a large nut called a slip nut holding them together. Place your adjustable wrench on that nut and turn it counterclockwise. You may be able to loosen it by hand first. Turn slowly—it doesn't need much force, and you don't want to strip the threads. Stop when water starts to drip into the bucket.
4. Loosen Bottom Connection. Now look at the bottom of the P-trap where it connects to the wall drain (or the horizontal pipe going into the wall). There's another slip nut there. Loosen it the same way—counterclockwise with your wrench. Again, work slowly and let water drip into the bucket.
5. Extract the Old Trap. Once both slip nuts are loose enough to turn by hand, unscrew them completely and set them aside. Pull the P-trap downward and away from the wall drain. It may be stuck from mineral buildup—rock it gently side to side and downward until it comes free. Let any remaining water drain into the bucket. You now have an empty trap in your hands.
6. Wipe the Threads Clean. Look at the tailpiece coming from the sink and the wall drain opening. Both will have old plumber's tape, mineral deposits, or dried putty around the threads. Wipe these clean with an old rag or paper towel. You want fresh, clean threads so the new slip nuts seal properly. Don't use anything abrasive—just wipe.
7. Fit and Trim the Trap. Hold your new P-trap loosely in place under the sink to see if it fits as-is. Most standard kitchen sinks have enough clearance for a standard trap, but some shallow cabinets or offset drains require cutting the tailpiece or trap arm. If it doesn't fit, mark where it needs to be cut with a permanent marker, remove it, and use a hacksaw or PVC cutter to make a straight, perpendicular cut. Sand the cut edge smooth with fine-grit sandpaper.
8. Tape the Top Threads. Wrap the threads of the sink's tailpiece with plumber's tape (also called PTFE or Teflon tape). Wrap it clockwise around the threads, covering all exposed threads with 3-4 layers. This gives the slip nut a tight seal without needing sealant compound. Plumber's tape is cheap and forgiving—if you mess up, just unwrap and start again.
9. Tape the Bottom Threads. Do the same thing at the wall drain outlet. Wrap plumber's tape clockwise around the threads, 3-4 layers, covering everything. If the wall drain fitting is plastic, be careful not to tear it.
10. Set Top Connection Loose. Slide the new P-trap into place, aligning the top connection with the sink tailpiece and the bottom connection with the wall drain. Insert the slip nut from the top (it may already be on the trap arm) and thread it onto the tailpiece by hand. Turn it clockwise until it's snug but still loose enough to turn with your fingers. Don't use a wrench yet.
11. Set Bottom Connection Loose. Thread the bottom slip nut onto the wall drain by hand. Again, turn it clockwise until it's snug. At this point, both nuts are hand-tight but not sealed. The trap should be stable in place.
12. Seal Both Connections. Now use your adjustable wrench to tighten each slip nut about a quarter turn more. This compresses the washers and seals the connections. Use firm but steady pressure—you're not cranking as hard as you can. Tighten the top nut first, then the bottom. If either nut feels like it's spinning rather than tightening, stop and check that you're turning it clockwise.
13. Verify No Leaks. Turn the water supply back on. Fill the sink with water and let it drain completely while watching the trap connections. Check both the top and bottom slip nuts for drips. If water pools slowly under the sink, let it drain completely and check again—sometimes it takes a moment. If you see a steady drip, turn off the water and tighten that nut another quarter turn with your wrench.