What is the maximum distance allowed from a 2" trap to its vent?

The maximum distance allowed from a 2" trap to its vent is 5 feet. This requirement is established in the Massachusetts Plumbing Code to ensure that plumbing systems function properly and prevent issues such as siphoning, which can lead to a loss of trap seal. When the distance from the trap to the vent is too great, it increases the risk of negative pressure in the system, which can draw water out of the trap and allow sewage gases to enter the living space.

The 5-foot maximum distance for a 2" trap strikes a balance that allows for adequate venting while minimizing the chances of failure in the trapping function. This distance is based on hydraulic principles and the need for proper airflow within the plumbing system, ensuring that traps remain effective in preventing backflow and odors from the sewer system.

In the context of other options, a lesser distance would not be suitable as it might hinder functionality in larger systems, while a greater distance would compromise the effectiveness of the venting and trapping relationship.