What type of traps are considered prohibited in plumbing installations?

Drum traps are considered prohibited in plumbing installations due to their design and function, which can lead to significant problems in wastewater drainage systems. These traps are large, cylindrical devices designed to hold water and prevent sewer gases from entering buildings. However, their structure tends to collect debris and solids over time, leading to frequent clogs. This accumulation can hinder drainage and create unpleasant odors, rendering them less effective than other trap types.

Moreover, drum traps can impede proper airflow within the waste system, leading to back pressure issues that can disrupt normal plumbing functions. Local plumbing codes often classify drum traps as an unacceptable choice because they do not provide the necessary clearances and accessibility for maintenance or cleaning, which is essential in maintaining a sanitary and functional plumbing system.

In contrast, full "S" traps, bell traps, and crown vented traps may still be in use under certain circumstances or updated codes, depending on their design and capacity to function effectively without the disadvantages that drum traps present.