Hierarchy classification:

1. top of the aat hierarchies
2. Objects Facet
3. Built Environment (hierarchy name)
4. Single Built Works (hierarchy name)
5. single built works (built environment)
6. [single built works by specific type]
7. [single built works by function]
8. hydraulic structures
9. [hydraulic structures by function]
10. drainage structures
11. sewers (drainage structures)
12. [sewers by function]

Anotations

Scope note:

Sewers that carry industrial or residential liquid and solid wastes but not ground, surface, or storm waters. For parts of building plumbing systems designed to dispose of similar wastes, use "sanitary drainage systems."