Definition check: What do we call the sewer that carries sewage from the collection system to the point of treatment or final discharge?

Introduction / Context:
Terminology in sewerage systems distinguishes between local collection conduits and the final conveyance to treatment. Correct naming ensures clarity in drawings, specifications, and operation manuals.

Given Data / Assumptions:

• Standard definitions in municipal engineering.
• Focus on conduit that conveys to treatment or final outfall.

Concept / Approach:
An out-fall sewer (also spelled outfall sewer) is the final trunk conduit that transports the collected wastewater to the treatment plant or discharge point. It is distinct from mains, branches, and laterals that make up the upstream collection network.

Step-by-Step Solution:
Identify network hierarchy: house → branch/lateral → main → trunk/interceptor → out-fall.The conduit delivering to treatment is the out-fall sewer.

Verification / Alternative check:
Textbook glossaries and standards consistently define “out-fall sewer” as the final conveyance to treatment/discharge.

Why Other Options Are Wrong:
Main/Branch/Lateral: Upstream network elements; not the terminal conveyance.House sewer: Private connection from premises, far upstream of the outfall.

Common Pitfalls:

• Confusing “trunk sewer” with the final out-fall; in many systems the out-fall is the terminal segment of the trunk.

Final Answer:
Out-fall sewer