What is the primary purpose of a plumbing trap?

The primary purpose of a plumbing trap is to act as a seal that prevents odors and gases from escaping into the living spaces of a building. Plumbing traps are designed to hold a small amount of water, which creates a barrier between the sewer system and the interior of the building. This water seal effectively blocks the entry of harmful sewer gases, ensuring that they cannot permeate the air in bathrooms, kitchens, and other areas where plumbing fixtures are located.

While plumbing systems do involve elements related to water pressure, management of water flow, and sometimes filtering contaminants, these are not the primary functions of a trap. The unique design of traps, such as U-shape or P-shape configurations, facilitates this crucial sealing role, demonstrating the significance of the trap in maintaining indoor air quality and preventing noxious smells from invading the household.