In plumbing, what is the purpose of a trap?

A trap in plumbing is primarily designed to prevent sewer gases from entering a building. This function is crucial for maintaining a safe and healthy indoor environment. Traps are typically U-shaped sections of piping that hold a small amount of water, creating a seal that effectively blocks noxious gases from rising up through the plumbing system into the living spaces.

While traps can collect some debris, the primary intent is not to catch debris but to ensure an airtight seal against these harmful gases. Similarly, traps do not primarily regulate water flow; they are more about maintaining a water seal. Cleaning of pipes is facilitated through access points, cleanouts, and not through the trap itself, which is primarily meant to serve as a barrier against unwanted odors and gases. Thus, the design and function of a trap are specifically oriented toward health and safety by mitigating the risk of harmful sewer gas infiltration.