What is the main purpose of a trap in plumbing?

The primary purpose of a trap in plumbing is to ensure that sewer gases do not enter the living space. A plumbing trap is a curved section of the pipe that holds a small amount of water at all times. This standing water acts as a barrier that prevents noxious gases from the sewer system from pushing back through the drainage system and entering homes or buildings.

Traps are a critical component of a plumbing system as they help maintain a healthy indoor environment by blocking unpleasant odors and harmful gases that can be a serious health hazard. The water seal within the trap effectively keeps these gases sealed away while still allowing wastewater to flow freely through the system.

While increasing water flow, preventing leaks, and enhancing drainage efficiency are important considerations in plumbing design, none of these directly corresponds to the primary function of a trap, which is specifically about preventing the ingress of sewer gases.