Which component of a sewage system helps in collecting and conveying sewage?

The public sewerage system serves as a crucial component in collecting and conveying sewage from multiple sources, such as homes and businesses, to a central treatment facility. This system consists of a network of pipes, pumps, and treatment plants designed to transport wastewater efficiently.

In contrast, the other options like the drain field, septic tank, and leach field function primarily in the treatment and disposal of sewage on-site rather than in the collection and transport aspects. The septic tank holds and partially processes the sewage, while the drain and leach fields provide a means for the effluent to be absorbed and treated naturally in the soil. However, they do not convey sewage over long distances to a treatment facility, which makes the public sewerage system the correct choice for the question regarding collecting and conveying sewage.