What is the minimum depth for exterior water supply system piping below the frost line?

The minimum depth for exterior water supply system piping below the frost line is typically established to prevent the pipes from freezing during cold weather. This is crucial in maintaining a functional water supply throughout winter conditions. The correct answer indicates that the piping must be installed at a depth of 6 inches below the frost line.

This consideration is based on the average frost depth in many regions, which is often used as a standard depth to avoid the risk of freezing water inside the pipes. Installing pipes below this level effectively insulates them from the colder surface temperatures that can lead to freezing, ensuring that the water supply remains operational.

Understanding the frost line is essential for proper installation and maintenance of plumbing systems in climates subject to freezing temperatures. While some regions may have deeper or shallower frost lines, the 6-inch depth provides a general guideline that aligns with many plumbing codes to protect the integrity of the water supply system.