What is the lowest pipe in a drainage system called?

The lowest pipe in a drainage system is referred to as the building drain. This component plays a crucial role in the plumbing system as it is responsible for collecting wastewater from various fixtures within the building and directing it to the municipal sewer or a private sewage treatment facility. Being the lowest point, the building drain is designed to ensure proper flow by utilizing gravity, preventing backflow and ensuring efficient drainage.

The building drain typically connects to the main sewer line, allowing for the safe removal of wastewater. Its design and proper installation are critical in preventing blockages and ensuring that the drainage system functions effectively. Understanding this concept helps in grasping how plumbing systems are organized and the importance of each component within the drainage network.