What is the purpose of a trap in plumbing systems?

The primary purpose of a trap in plumbing systems is to create a water seal that prevents sewer gases from entering living spaces. Traps are designed to retain a small amount of water, which forms a barrier between the plumbing system and the atmosphere, effectively blocking the passage of harmful gases that can cause odors and health hazards. This function is crucial for maintaining a safe and sanitary environment in homes and buildings.

While traps do hold some water, their main function goes beyond just storage; it is their ability to form a seal that is essential for safety. Traps do not typically filter debris; their design is not intended for that purpose but rather to allow wastewater to flow while preventing the backflow of gases. Additionally, while traps are part of the plumbing system that connects to drain lines, their primary role is not merely to connect sewer lines but to serve as a barrier against gas escape.