What is the required trap seal range?

The required trap seal range is defined as the minimum depth of water that should remain in a plumbing trap to effectively prevent sewer gases from entering the living spaces of a building. The correct answer reflects that this range is specifically between 2 to 4 inches.

This range is critical because a trap that is too shallow may fail to create an adequate seal, allowing harmful gases to escape into the home, which poses health risks. Furthermore, on the low end of this range, a trap must have at least 2 inches to maintain a sufficient barrier, while the maximum limit of 4 inches ensures that the trap is not overly filled to the point of hindering drainage.

Understanding the required trap seal range is essential for maintaining proper plumbing function and safety, and it is a key point of knowledge for anyone preparing for a plumbing certification or licensure exam.