What Is a P-Trap?
A P-Trap is a curved plumbing fitting beneath a sink, shower, tub, or other fixture drain. The fitting holds a small amount of water in its bend, creating a seal that blocks sewer gases from entering the room. P-Traps also connect the fixture drain to the building’s drainage pipe.
Quick Facts About P-Trap
Category
Drain fitting
Used for
Blocking sewer gases
Common confusion
Often confused with a drain vent
Also called
Plumbing Trap, Sink Trap
Often discussed with
Drain Cleaning
Key Takeaways About P-Trap
- Its curved shape holds a water seal.
- Blockages often collect inside the trap.
- A P-Trap is not the same as a vent.
How P-Trap Works
A P-Trap holds water in its curved section after a fixture drains. That water forms a seal inside the pipe. The seal blocks sewer gases from moving through the drain opening.
Related glossary terms: Drain Auger, Sewer Cleanout, Trap Primer.
Water and waste pass through the trap when you use the fixture. Hair, grease, soap, and small objects can collect there and slow drainage. During drain cleaning, we may inspect the trap, clear the blockage, or remove and clean the fitting when access allows.
A drain vent supports steady water flow by balancing air pressure in the drainage system. The P-Trap serves a different purpose, since its water seal limits odors at the fixture.
Expert Note
When we handle drain cleaning, we check the P-Trap when a fixture drains slowly or backs up. We look for buildup, leaks, loose connections, and a missing water seal. We also check nearby drain parts so clearing one blockage does not hide another problem.
P-Trap in Practice: A Real-World Example
A bathroom sink drains slowly, and water remains in the basin. We inspect the P-Trap for hair and soap buildup, then clear the fitting if the blockage sits there.
Related Services
Related Terms
Drain Auger
A Drain Auger is a plumbing tool with a flexible cable that clears blockages inside drain…
Sewer Cleanout
A Sewer Cleanout is an access point on a building’s drain line that lets a plumber…
Trap Primer
A trap primer is a plumbing device that sends water into a drain trap to keep…
Vent Stack
A vent stack is a vertical plumbing pipe that carries sewer gases outside and lets air…
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