What minimum slope is required for pipes 3 inches and smaller?

The minimum slope required for pipes that are 3 inches in diameter or smaller is indeed 1/4 inch per foot. This standard is established to ensure that wastewater and other materials flow properly through the drainage system. A slope that is too shallow may not provide adequate drainage, leading to issues like clogs or backups. The 1/4 inch per foot slope is often considered the minimum for efficient drainage in smaller pipes, allowing for gravity to effectively pull waste along without allowing solids to settle in the pipe, which could cause blockages or reduced flow over time.

Understanding these slope requirements is crucial for plumbing design to ensure long-term functionality and compliance with plumbing codes.