Trunk Sewer

Definition - What does Trunk Sewer mean?

A trunk sewer is a large sewer used to convey waste from smaller tributaries toward the waste treatment plant. It is part of a multi-tiered wastewater collection system in a city or metropolitan area. In some systems, it may be referred to as a main sewer, while others consider main sewers as its tributaries.

Large pipes or tunnels like these in a sewage system are often installed or maintained using trenchless construction techniques.

Trenchlesspedia explains Trunk Sewer

In a large metropolitan area, the sewer system can be vast and complex. While the nomenclature may vary from city to city, trunk sewers are major components of the system.

Taking advantages of gravity as well as pumping where needed, a large sewer system moves wastewater from homes and business down ever-larger tributaries until it reaches its destination for treatment. The tiers of a sewer system can be laid out in this way:

  • Building sewer
  • Branch sewer
  • Main sewer
  • Trunk sewer
  • Interceptor sewer

The terms are useful for describing the size of the pipes or volume of wastewater in a particular region of the sewer system. While the designations are not arbitrary, the terms may be locally determined or assigned during installation. A trunk sewer pipe might be 24-48-inches, depending on the designation.

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