What function does a trap serve in plumbing?

A trap in plumbing primarily serves the critical function of preventing sewer gases from entering buildings. It achieves this by creating a water seal that acts as a barrier between the plumbing system and the atmosphere. When wastewater flows through the trap, it fills a portion of the trap with water. This water seal is vital because it blocks harmful gases, such as methane and hydrogen sulfide, that are found in the sewer system. By maintaining this seal, traps help to ensure a safe and healthy indoor environment.

The other functions related to plumbing systems, such as filtering solids, connecting drainage lines, or regulating water pressure, are not primary roles of a trap. Filtering solids is typically handled by other mechanisms, such as strainers or filters. Connections between drainage lines are made using fittings and connectors, while water pressure regulation is managed by specific devices designed for that purpose, like pressure regulators or valves. Understanding the specific role of a trap emphasizes its importance in maintaining both the safety and functionality of plumbing systems.