What is the function of a P-trap in a plumbing system?

The function of a P-trap in a plumbing system primarily centers around maintaining a water seal that prevents sewer gases and odors from entering the living spaces of a building. A P-trap is a curved section of pipe located under sinks, tubs, and other fixtures. When water flows through the trap, it fills the curved section and creates a sealed barrier. This water seal is crucial because it blocks the passage of gases from the drainage system while still allowing wastewater to flow freely out of the plumbing fixture.

In terms of plumbing code, having this feature is essential for hygienic reasons. Foul odors from the sewer can be not only unpleasant but also harmful, and the P-trap ensures a level of safety in indoor air quality. Additionally, it allows for proper drainage by accommodating the water flow without interfering with the overall plumbing efficiency.

While preventing backflow, facilitating drainage, and holding pressure are important aspects of plumbing design, these functions don't specifically pertain to the role of the P-trap. The primary and standout function of the P-trap is its ability to maintain that crucial water seal to inhibit odors effectively.