What is the minimum depth of a trap seal in inches?

The minimum depth of a trap seal is crucial for maintaining the proper function of a plumbing system, as it ensures that the trap can effectively block sewer gases while allowing wastewater to pass. A seal depth of 2 inches is established by standards and codes because it provides sufficient water to prevent sewer gas from escaping while also ensuring that the trap does not dry out too quickly, which could lead to odors in a building.

Depths less than 2 inches may not effectively form a water barrier against gases, as they could evaporate faster, especially in low-use fixtures. Therefore, a seal depth of 2 inches is the accepted standard to ensure both performance and code compliance in plumbing installations. The other depths provided exceed this minimum requirement but do not reflect the standardized depth necessary for effective trap functionality in most residential and commercial applications.