How often should you clean a sink P-trap?
Updated July 2026
Pull and clean a sink P-trap once a year, and immediately whenever that sink starts to drain slowly or breathes a sewer smell. The trap is the U-shaped bend under the basin, and it does two jobs at once: it holds a 2-inch plug of water that blocks sewer gas, and it catches the hair, soap scum, grease, and stray earrings that would otherwise ride down the line. Kitchen traps that see grease and food need it closer to every 6 months. It is a 10-15 minute job with a bucket and gloves, no chemicals required.
What changes the interval
| Your situation | Interval | Why |
|---|---|---|
| Bathroom sink (hair and soap scum) | Once a year | Hair binds with soap into a mat that narrows the bend |
| Kitchen sink (grease and food) | Every 6 months | Cooled grease coats the trap and grabs everything after it |
| Sink drains slow or gurgles | Clean now | The gurgle is air fighting past a partial blockage |
| Sewer or musty smell at the drain | Clean now | Either the trap dried out or gunk in it has gone sour |
| Guest or rarely used sink | Run water monthly | A dry trap loses its seal and lets sewer gas in |
| Dropped a ring or small item | Open the trap | The bend is exactly where small objects come to rest |
The cost of skipping it
What skipping it costs: a neglected trap goes from slow to fully blocked, and the panic move is a bottle of chemical drain cleaner ($8-20). Those caustic gels sit on the clog generating heat, soften and warp PVC, corrode older metal traps, and rarely clear a real grease plug. When the DIY fails, a plumber's snake or trap swap runs $150-350, and a corroded trap arm that has to be replaced adds parts and time. A yearly cleaning that costs nothing but 15 minutes heads all of that off. Keep it on the home maintenance checklist.
How to do it (10-15 minutes · DIY, bucket + gloves)
- Set a bucket or shallow pan under the trap to catch the standing water inside it.
- Unscrew the two slip nuts by hand (or with channel-lock pliers) and lower the curved trap section away.
- Dump it out, then scrub the inside with a bottle brush and hot soapy water until the walls are clean.
- Check the slip-nut washers for cracks and inspect the trap arm going into the wall for buildup.
- Reassemble, hand-tighten the slip nuts plus a quarter turn, and run hot water while watching for drips.
Knowing the interval is the easy half. OnOtto reminds you at the right interval, and it won't let you snooze it into next year. Tasks persist until they're done, and completing P-trap cleanings schedules the next one automatically.
Put this on autopilot, free for 30 daysFrequently asked questions
Can I just use a chemical drain cleaner instead of opening the trap?
You can, but it is the worse option. Caustic and acid drain cleaners ($8-20 a bottle) generate heat that can warp PVC and pit metal, they seldom dissolve a grease or hair mat completely, and any leftover chemical makes the eventual hands-on cleanup hazardous. Opening the trap takes the same 15 minutes, costs nothing, and actually removes the clog instead of pushing it deeper. Save the chemistry for a last resort on a fully sealed drain you cannot reach.
Why does my sink still smell after I cleaned the trap?
Two usual suspects. If the sink sits unused, the trap water evaporates and sewer gas rises straight through the dry bend, so just run the tap for 30 seconds to refill the seal. If the smell persists on a working sink, the odor is often biofilm on the overflow hole, the stopper, or a nearby garbage disposal rather than the trap itself. Scrub those, and flush with hot water and a little baking soda.
The trap is clean but the sink is still slow. Now what?
Then the blockage is downstream of the trap, in the trap arm or the branch drain inside the wall. Feed a small hand auger (a $15-25 drum snake) through the trap arm and crank it out a few feet to catch the obstruction. If several fixtures drain slowly at once, the problem is further down the main line, and that is a job for a plumber's power auger or a camera scope rather than more work at the sink.
Should I replace the P-trap or just clean it?
Clean and reuse it if the plastic is sound and the walls are not cracked or crusted with mineral scale. Do replace the two slip-nut washers if they look flattened or split, since a hardened washer is the most common cause of a slow under-sink drip. A full PVC trap kit is only $8-15 at any hardware store, so if the trap is old metal that is corroding or the threads are stripped, swapping the whole assembly is cheap insurance.