What is the drainage pipe that extends horizontally from a soil or waste stack or building drain called?

The drainage pipe that extends horizontally from a soil or waste stack or building drain is referred to as a horizontal branch drain. This component is essential in plumbing systems as it allows the collected waste and sewage to flow away from fixtures and into the main drainage system.

The horizontal branch drain is typically connected to multiple fixtures, facilitating the efficient movement of wastewater from bathrooms, kitchens, and other plumbing applications toward the main drain or sewer line. Its design is crucial for maintaining proper drainage and minimizing the risk of blockages, ensuring that waste is effectively transported away from areas where it is generated.

In contrast to other terms: a vertical drain refers to pipes that run straight up and down, and soil pipes are specifically designed to carry waste from toilets or similar fixtures but do not necessarily describe the horizontal aspect. The main drain generally refers to the principal waste conduit that collects and directs all waste from branch drains and other pipes but doesn’t specify the horizontal nature of the branch itself.