Bucket or shallow pan
Use it for: Catches the water and debris that spill out when the trap comes apart.
Shop drain catch panPlumbing repair
How to Replace a Drain Trap
To replace a drain trap, confirm the trap is the source of the leak or sewer smell, remove the old trap, dry-fit the new parts, tighten the slip joints evenly, and test with a full sink of water.
A drain trap holds water to block sewer gas and carries wastewater into the drain line. If it is cracked, corroded, loose, or badly misaligned, replacement is usually faster and more reliable than trying to patch it.
Before you start: Match the pipe diameter, inlet and outlet layout, and trap style before ordering.
Safety first
- Wear gloves if the old trap contains dirty water or debris.
- Keep a bucket under the trap during removal to avoid cabinet water damage.
- Do not force wall piping sideways to make a new trap fit.
- Use only light tool pressure on plastic slip nuts to avoid cracking them.
Tools you may need
Channel lock pliers
Use it for: Helps loosen and snug slip nuts without crushing plastic parts.
Shop channel-lock pliers
Adjustable wrench
Use it for: Useful if the trap has metal nuts or stubborn threaded connections.
Shop adjustable wrench
Rags or paper towels
Use it for: Wipes the pipes clean so the new washers can seal properly.
Shop shop towels
Tape measure
Use it for: Checks pipe diameter and helps you trim or position the new trap correctly.
Shop tape measure
Hacksaw or fine tooth plastic pipe saw
Use it for: Cuts a new trap arm or extension tube to length if the kit is oversized.
Shop plastic pipe sawAs an Amazon Associate I earn from qualifying purchases. Repair Riot may earn a commission at no extra cost to you.
Step-by-step fix
Step 1: Confirm the drain trap is the right repair
- Place a bucket under the trap and dry the trap, slip nuts, and nearby pipe connections with a rag.
- Run a small amount of water, then watch for drips from the curved trap body, the slip-joint nuts, or visible cracks.
- Smell near the sink or drain opening after the water stops. A dry, cracked, or poorly sealed trap often lets sewer odor escape.
- Check that the problem is at the trap itself, not higher up at the sink strainer, tailpiece, disposal connection, or inside the wall.
If it works: You have confirmed the trap is leaking, cracked, badly corroded, missing, or misaligned enough that replacement makes sense.
If it doesn’t: If the leak starts above the trap, repair that connection first. If there is no leak but the drain smells, run water to refill the trap and check for a loose or dry connection before replacing parts.
Stop if:
- The leak appears to come from inside the wall or cabinet floor is soft, swollen, or mold-damaged.
- The drain piping is broken, heavily rusted, or so seized that removal may damage piping in the wall.
Step 2: Set up the area and remove the old trap
- Clear out the cabinet or work area so you can reach both trap connections comfortably.
- Put the bucket directly under the trap bend.
- Loosen the slip nuts by hand first, then use pliers only as needed. Support the trap as the last nut comes free.
- Lower the trap slowly and dump the trapped water into the bucket.
- Remove any old washers and clean the pipe ends so you can see the sealing surfaces clearly.
If it works: The old trap is out and the connecting pipes are exposed, clean, and ready to inspect.
If it doesn’t: If a nut will not move, apply steady pressure and avoid twisting the wall pipe. A little back-and-forth motion often breaks it loose.
Stop if:
- A wall stub-out or sink tailpiece starts turning in a way that could loosen hidden piping.
- The pipe end is split, badly out of round, or too damaged to seal with a new trap.
Step 3: Match and dry-fit the new drain trap
- Lay out the new trap pieces in the same orientation as the old assembly.
- Confirm the new trap matches the pipe diameter and reaches the sink tailpiece and wall drain without forcing either pipe sideways.
- Slide the slip nuts and washers onto the pipes in the correct direction, with the tapered side of each washer facing the joint it will seal.
- Dry-fit the trap bend and trap arm before tightening anything. Trim only the minimum amount if a tube is too long.
- Keep the trap centered and slightly pitched toward the wall drain through the trap arm, not tilted or twisted at the trap bend.
If it works: The new trap fits naturally between the sink drain and wall drain with no strain on the joints.
If it doesn’t: If the kit does not line up, recheck the diameter, trap style, and whether you need an extension tube or a different trap arm length.
Stop if:
- The only way to make it fit is to force the pipes out of alignment.
- The wall opening is too high, too low, or too far off-center for a standard trap replacement to seal correctly.
Step 4: Assemble and tighten the new trap
- Start all slip nuts by hand so the threads do not cross.
- Seat each washer squarely, then tighten the nuts hand-tight first.
- Use pliers or a wrench to snug each nut a little more if needed, but do not overtighten. Plastic nuts can crack and overtightened washers can leak.
- Make sure the trap bend remains directly under the drain and the trap arm stays fully inserted and aligned with the wall pipe.
- Wipe every joint dry so even a small leak will be easy to spot during testing.
If it works: The new trap is installed, aligned, and tightened enough for testing.
If it doesn’t: If a nut feels crooked or binds early, back it off and restart the threads by hand before tightening again.
Stop if:
- A plastic nut cracks, a washer slips out of place, or a pipe will not stay seated in the joint.
Step 5: Test for leaks and proper drainage
- Run a slow stream of water for about 30 seconds while watching each joint closely.
- If dry, fill the sink partway and release the water to send a stronger flow through the trap.
- Touch each slip joint with a dry finger or paper towel to catch small leaks you might not see.
- If a joint drips, tighten that nut slightly and test again. If it still leaks, take it apart and reseat the washer.
- Listen for smooth drainage. The trap should drain without backing up at the sink or dripping under load.
If it works: The trap stays dry during both a light flow and a full-drain test, and the sink drains normally.
If it doesn’t: If the trap stays dry but the sink drains slowly, clear the drain line or check for a clog farther downstream.
Stop if:
- Water leaks from the wall connection, behind the cabinet, or from another pipe you did not disturb.
- The sink backs up immediately, suggesting a blockage beyond the trap rather than a trap problem.
Step 6: Confirm the repair holds in real use
- Use the sink normally several times over the next day, including one full-basin drain if possible.
- Check the cabinet floor and all trap joints again after the sink has been used with warm and cold water.
- Smell near the drain and under the sink. A properly installed trap should hold water and block sewer gas.
- Retighten only if you find a slight drip. If the joints remain dry, leave them alone.
If it works: The new drain trap stays dry in normal use and sewer odor is gone or greatly reduced.
If it doesn’t: If odor remains with a full, leak-free trap, inspect the sink strainer seal, overflow passage, and nearby venting or drain issues.
Stop if:
- Leaks return repeatedly after reseating and light tightening, which usually means the wrong parts, damaged pipe ends, or a larger drain alignment problem.
Replacement Parts
Find a drain trap on Amazon
Match the pipe diameter, inlet and outlet layout, and trap style before ordering.
As an Amazon Associate I earn from qualifying purchases. Repair Riot may earn a commission at no extra cost to you.
Verify the repair
- The trap and all slip joints stay dry during a slow-flow test and a full sink drain.
- The sink drains without gurgling at the trap or leaking under the cabinet.
- There is no sewer smell under the sink after the trap has been filled with water.
- The trap sits aligned without putting side pressure on the tailpiece or wall pipe.
FAQ
Do I need plumber's tape on a drain trap?
Usually no. Most drain trap slip joints seal with tapered washers, not thread tape. Tape on slip-joint threads usually does not fix a bad fit or a misseated washer.
Why does my new drain trap still leak at the nut?
The most common causes are a crooked washer, crossed threads, pipe misalignment, or overtightening that distorts the washer. Take the joint apart, clean it, reseat the washer, and reassemble it squarely.
Can I reuse the old washers?
It is better to use the new washers that come with the replacement trap. Old washers often harden, flatten out, or no longer match the new parts well enough to seal reliably.
What if the sink still smells after I replace the drain trap?
First make sure the trap is holding water and not leaking. If it is full and sealed, the odor may be coming from the sink strainer area, overflow passage, buildup in the drain line, or another venting or drain issue.
How tight should a plastic drain trap be?
Start hand-tight, then add only a small amount with pliers if needed to stop a drip. It should be snug, not cranked down hard. Overtightening can crack the nut or deform the washer.