According to the National Plumbing Code, what is the maximum permissible slope for drainage pipes?

The maximum permissible slope for drainage pipes specified in the National Plumbing Code is critical for ensuring proper water flow and preventing issues such as blockages and inadequate drainage. A slope of 1:50, or 2%, is designed to provide sufficient gravity assistance for waste and water to move effectively through the pipes without being too steep, which could lead to problems like increased wear on the system, splashing or turbulence, and a higher likelihood of premature pipe failure.

When the slope is too steep, such as a slope of 1:30 or 1:25, it can cause solids to escape from the water flow energy, resulting in blockages. Conversely, a slope that is too gentle, like 1:100, does not provide adequate drainage, leading to stagnant water and potential sewer gas issues. Thus, maintaining a slope of 1:50 is a balance that supports efficient flow and system longevity, making it the correct choice based on the standards set by the code.