What is the purpose of a plumbing trap?

The purpose of a plumbing trap is to hold water and create a seal that prevents sewer gases from entering the home. Traps are designed to retain a small amount of water at all times, which forms a barrier between the sewer line and the interior living spaces. This barrier not only keeps harmful odors and gases from seeping into occupied areas but also helps to ensure that vermin cannot travel back through the plumbing system.

Plumbing traps are commonly found in various fixtures such as sinks, bathtubs, and toilets, and their design is essential for maintaining indoor air quality and preventing health hazards. While traps do play a role in facilitating drainage by allowing waste to flow through, their primary function remains the prevention of sewer gas intrusion.