Which plumbing fixtures typically require a trap?

Traps are essential components in plumbing systems, as they serve to prevent sewer gases from entering a building while allowing wastewater to flow through. Sinks, tubs, and showers require traps specifically because these fixtures produce wastewater that needs to be safely conveyed to the drain system.

The design of a trap retains a small amount of water, creating a barrier that blocks odors and harmful gases from the sewer system. For fixtures like sinks, tubs, and showers, which regularly handle water and waste, having a trap is critical for both health and safety.

In contrast, toilets and urinals are designed with integrated traps, and while they also need to prevent sewer gases from escaping, they function differently than other typical fixtures. Kitchen faucets do not directly require traps; they are part of a system that uses traps in conjunction with sinks. Lastly, dishwashers and washing machines typically connect to existing traps rather than having separate ones designed just for their specific waste disposal needs. Therefore, sinks, tubs, and showers are the fixtures that clearly require dedicated traps to maintain optimal plumbing function and safety.