What is the purpose of a trap in a plumbing system?

The primary function of a trap in a plumbing system is to prevent sewer gases from entering the building. Traps are designed to maintain a small amount of water in the bend of the pipe, which acts as a barrier. This water seal prevents harmful gases, such as methane and hydrogen sulfide, that can originate from the sewage system from escaping into the living spaces of a building.

Additionally, the trap serves as a catchment for debris that may enter the drainage system, preventing it from clogging further pipes. However, the crucial aspect remains its role in ensuring that no noxious odors or gases can seep into the indoor environment, which is vital for maintaining air quality and safety in the home. By fulfilling this function, traps contribute significantly to the overall health and safety standards of plumbing systems.

The other choices relate to aspects of plumbing that are either secondary effects or unrelated to the core purpose of a trap. For instance, preventing water waste generally involves different aspects of water management rather than the function of traps. Increasing water flow is more about pipe sizing and design rather than traps. Filtering impurities pertains to water treatment and filtration systems, rather than the function of a trap within the drainage system.