What is the minimum water seal depth required for traps?

The minimum water seal depth required for traps is 2 inches. This measurement is critical because the water in the trap creates a barrier that prevents sewer gases from entering the living space. A water seal of at least 2 inches is deemed necessary to ensure that there is enough water to maintain this barrier under typical operating conditions, including fluctuations in water levels that may occur during usage. A trap with less than 2 inches of water seal may not effectively block these gases, potentially leading to health hazards and unpleasant odors in the home. Thus, adhering to this requirement is essential for proper plumbing and ventilation in residential structures.