What is the required liquid seal size for each fixture trap?

The required liquid seal size for each fixture trap is essential to ensure proper drainage and to prevent sewer gases from entering the living spaces. A liquid seal size of 2 inches minimum and 4 inches maximum is established to provide adequate space for water while effectively blocking any unwanted gases.

This range allows for sufficient liquid to form a barrier, which is critical for traps to perform effectively. If the seal is too small, it may not hold enough water to adequately prevent gases from rising, while an overly large seal could impede water flow and drainage efficiency. Thus, maintaining a seal within this range supports both the functionality and safety of plumbing systems in residential and commercial environments.