Within municipal wastewater infrastructure, which of the following is generally NOT referred to as part of the sewerage system? (Identify the distractor that does not represent a recognized sewer category.)

Introduction:
Sewerage systems convey wastewater and stormwater through underground pipe networks. This question checks familiarity with standard sewer classifications used by civil/environmental engineers and utilities.

Given Data / Assumptions:

• Commonly recognized categories: sanitary (domestic/industrial wastewater), storm (runoff), and combined (both flows in one pipe).
• Terminology should be technically standard and found in design manuals.
• We are looking for a term that is not used in practice.

Concept / Approach:
Standard nomenclature distinguishes by type of conveyed flow. The phrase “solid sewers” is not a technical category; solids are conveyed within wastewater but do not define a separate class of sewers. Hence it functions as the distractor among otherwise valid categories.

Step-by-Step Solution:
List accepted sewer types: sanitary, storm, combined. Check each option against standard definitions. Recognize “solid sewers” as non-standard terminology. Select the non-recognized category as the correct choice.

Verification / Alternative check:
Design standards and public works documentation uniformly use sanitary, storm, and combined—no authoritative source defines “solid sewers.”

Why Other Options Are Wrong:

• Sanitary sewers: Carry domestic/industrial wastewater to treatment.
• Storm sewers: Convey rainfall runoff to receiving waters or detention.
• Combined sewers: Carry both; legacy systems in older cities.

Common Pitfalls:
Assuming “solid sewers” refers to sludge lines; sludge handling is separate and not a general sewer category.

Final Answer:
Solid sewers is not a recognized part of the sewerage system.