What is the most common type of plumbing trap used in a house today?

The most common type of plumbing trap used in residential settings today is the P-trap. This design is widely utilized because it effectively prevents sewer gases from entering the home while allowing wastewater to flow freely. The P-trap's shape, which resembles the letter "P," creates a water seal that retains a small amount of water, serving as a barrier against odors and harmful gases. This characteristic is crucial for maintaining indoor air quality.

In comparison to other trap designs, the P-trap is favored for its practicality, ease of installation, and effectiveness in a variety of plumbing applications, such as under sinks and lavatories. Its design is also compliant with modern plumbing codes, which mandate the use of traps in drainage systems.