Which plumbing fixture typically requires a trap as part of its design?

A sink typically requires a trap as part of its design to prevent sewer gases from entering the living space. The trap is a curved section of pipe that holds a small amount of water, creating a barrier between the drainage system and the home. This water seal is essential for blocking harmful odors and potential pathogens that could arise from wastewater. Sinks, when used, drain water and waste, necessitating a trap to maintain sanitary conditions.

While toilets also have a trap, they are designed differently and often have an integrated trap within the fixture itself, making them distinct from sinks which require an external trap installation. Water heaters and faucets do not involve wastewater management in the same way, and therefore, do not require traps. The design and operational needs of a sink distinctly highlight the necessity for a trap to ensure safe and hygienic plumbing practices.