According to the code, what is the minimum slope required for a building sewer?

The minimum slope required for a building sewer is established to ensure proper drainage and to prevent accumulation of waste materials within the piping system. A slope of 1% or 1/8 inch per foot is designed to facilitate the movement of wastewater through the sewer pipe without risking clogs or stagnation. This specific slope represents a balance that allows for adequate flow while minimizing potential issues such as backflow or blockages.

When the slope is set accurately, gravity assists in transporting sewage effectively down to the municipal sewer or septic system, ensuring compliance with plumbing regulations that prioritize the safety and health of the building occupants as well as the environment. Sufficient slope prevents the formation of "lazy" spots that can lead to issues with drainage systems, keeping the plumbing functional and efficient over time.