What is the purpose of a building drain?

The purpose of a building drain is to convey sewage from the building to the property boundary. This system is fundamental in plumbing as it is designed to transport wastewater, including sewage, away from the structure, ensuring that it is directed to the appropriate waste management system, such as a public sewer line or a septic system.

A building drain typically includes pipes and fittings that ensure the smooth flow of wastewater and prevent blockages or backflows, which could lead to contamination or damage. By functioning in this way, the building drain plays a crucial role in maintaining sanitary conditions within the property while facilitating the safe disposal of sewage.

Options that suggest collection of surface water runoff, treatment of sewage, or filtering of sewage are functions that pertain to different systems or processes in wastewater management. Surface water runoff is typically handled by stormwater drainage systems, while treatment and filtration are processes that occur at sewage treatment facilities, not within the building drain itself.