What is the primary purpose of a trap in plumbing?

The primary purpose of a trap in plumbing is to prevent sewer gases from entering the building. Traps are typically U-shaped sections of pipe located beneath sinks, toilets, and other drainage fixtures. They maintain a small amount of water in the bend of the U, which acts as a barrier, effectively sealing off the plumbing system from the sewer line. This barrier is crucial because sewer gases can be hazardous to health, containing harmful constituents that can lead to unpleasant odors and are potentially hazardous if inhaled.

While traps do connect drainage pipes in a way, that is not their primary function. Their essential role is more focused on creating a seal against gases than on simply bridging sections of pipe. Similarly, traps do not have a function in regulating water pressure or filtering impurities from water; those tasks are managed by different plumbing components and systems designed specifically for those purposes. Understanding the function of traps is essential for proper plumbing design and ensuring the health and safety of the building's occupants.