How to Clean a P-Trap
Updated February 20, 2026
Clear a clogged or smelly P-trap in minutes. No special tools needed -- just a bucket, pliers, and a brush. Fixes slow drains and sewer odors at the source.
Overview
The P-trap is the U-shaped pipe under every sink. It holds a small plug of water that blocks sewer gas from coming up through the drain. It also catches debris -- hair, soap scum, food particles, grease -- which is why it clogs more than any other part of the drain. Cleaning a P-trap takes 10-20 minutes, requires no special tools, and fixes both slow drains and bad odors. If your sink drains slowly or smells like a sewer, the P-trap is the first place to look.
What You'll Need
Safety First
- Place a bucket under the P-trap before loosening anything. The trap holds water and trapped debris that will spill when you disconnect it.
- If you have a garbage disposal, make sure it is OFF and unplugged before working under the sink.
Step-by-Step Instructions
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Place a Bucket and Clear the Cabinet
Clear everything from under the sink. Place a bucket or large bowl directly under the P-trap. The trap holds water -- it will spill when you disconnect it. Have rags ready for drips.
Tip: Spread a towel on the cabinet floor in case the bucket overflows. P-trap water is stagnant and can smell. -
Disconnect the P-Trap
Most P-traps have two slip-joint nuts -- one where the trap connects to the tailpiece (coming down from the drain) and one where it connects to the wall pipe (stub-out). Loosen both nuts by hand if plastic, or with channel-lock pliers if metal. Turn counterclockwise. Pull the trap straight down and let it drain into the bucket.
Tip: Plastic P-traps: hand-tight only. Do not use pliers on plastic nuts unless they are truly stuck -- over-tightening cracks them. Metal traps may need pliers but wrap the jaws with tape to avoid scratching chrome. -
Clean the Trap
Dump the contents into the bucket. You will likely find a plug of hair, soap, grease, or food debris. Use a bottle brush or old toothbrush to scrub the inside of the trap. Flush it with hot water. If there is heavy buildup, soak in hot water with dish soap or a 50/50 vinegar-water mix for 15 minutes, then scrub again.
Tip: While the trap is off, check the tailpiece and wall pipe for buildup too. Push a rag through with a screwdriver or use a small brush. Clogs often extend past the trap. -
Inspect the Washers
Each slip-joint nut has a nylon or rubber washer (beveled ring) that creates the seal. Check them for cracks, hardening, or deformation. If they are worn, replace them -- washer kits are $2-3. The bevel faces toward the nut (away from the trap body).
Tip: Cracked washers are the most common cause of leaks after reassembly. If the trap is old and the washers are hard, replace them now while it is apart. -
Reassemble and Test
Slide the washers onto the tailpiece and wall pipe (bevel facing the nut). Lift the P-trap into position and hand-tighten both nuts. Snug plus a quarter turn with pliers if metal. Run water for 30 seconds and check every connection for drips. Tighten slightly if needed -- do not overtighten.
Tip: If it leaks after tightening, take it back apart and check that the washers are seated correctly (bevel facing the right direction) and that the pipes are aligned straight. Misalignment causes leaks even with new washers.
Pro Tips
- Clean the P-trap every 6-12 months as preventive maintenance. Do not wait for a full clog.
- Kitchen P-traps clog with grease. Run hot water for 30 seconds after washing greasy dishes to push grease past the trap before it solidifies.
- Bathroom P-traps clog with hair. A $3 mesh drain screen catches hair before it enters the trap.
- If the P-trap is corroded, cracked, or heavily scaled, replace it. A new plastic P-trap is $5-10 and takes the same amount of time to install as cleaning the old one.
- Sewer smell but the trap looks clean? The water seal may have evaporated from a sink that is not used often. Run water for 10 seconds to refill the trap.
When to Call a Pro
Cleaning a P-trap is always DIY. But if the drain is still slow after cleaning the trap, the clog is deeper in the wall pipe or main drain line. If you hear gurgling from other fixtures when you run this sink, a vent issue may be involved. Both of those are plumber territory.