Sewer system

A sewer system comprises a network of pipelines that collect and transport waste and stormwater to a wastewater treatment plant or the receiving waters.

A sewer system comprises a network of pipelines and technical installations (e.g. pumping stations). The system collects and transports waste- and stormwater from more than one source to a wastewater treatment plant or the receiving waters.

The sewer system can be either a combined or separate sewer system. The combined sewer system transports both sanitary wastewater (liquid and waterborne wastes from residences, commercial buildings, industrial complexes etc.) and surface/stormwater in the same pipeline. The separate sewer transports wastewater in a separate sanitary sewer pipeline and stormwater in another pipeline called the storm sewer.

The branched sewer network is divided into smaller units termed lateral, collector, trunk and intercepting sewer:

1. Lateral Sewer
   A conduit that receives sewage or stormwater from residential, commercial or industrial structures and discharges into a public collector sewer.
2. Collector Sewer
   A conduit that receives sewage or stormwater from two or more lateral sewers or other branch conduits.
3. Trunk Sewer
   A principal sewer which collects the flow from two or more collector sewers.
4. Intercepting Sewer
   A sewer that receives sewage from a number of collector and trunk separate sewers and specific, limited/controlled quantities of wastewater from combination sewers through diversion structures and conveys that wastewater to a point for treatment or disposal.

Through the sewer system the wastewater can either be transported by gravity or by pumping:

• Gravity main
  Flow is caused by the force of gravity and the pipeline is designed usually to operate partially full.
• Rising main
  A pipeline from a pumping station through which a liquid is transported under pressure. A rising main is used to transport sewage where gravity flow is not possible or practical.

Grundfos ensures a better system design for wastewater networks of which the sewer system is an integral part.