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Sewer School: How Does a Sewer Force Main Work?

Posted by Olivia Singer on Jan 11, 2021

Sewer systems are made up of various components that work together to transport wastewater from homes and buildings to a facility for treatment.

Wastewater initially travels through a lateral pipe on an individual property before combining with the wastewater of neighboring properties in the sewer main located under a nearby street. From there, the wastewater travels through a network of pipes until it eventually reaches a treatment plant for reuse or recycle.

Sewer System Map

Gravity Lines vs. Force Mains

In most cases, the primary force pushing the wastewater from its place of origin to its final location for treatment is gravity. That means no mechanical or power sources are required to move the wastewater along. 

But what about wastewater that needs to travel from low-lying areas up steep hills to higher elevations? In systems where gravity cannot transport the wastewater from point A to point B, pressurized sewer pipes, called force mains, are required.

Force mains rely on mechanical pumps or compressors located in a lift station to create the pressure to drive the wastewater up to higher elevations. This provides a solution for regions where the topography can’t support a gravity-reliant system, ensuring the wastewater still gets where it needs to go. 

Sewer Force Main

Maintaining Force Mains

Force mains may be constructed from one of a number of materials, including cast iron, steel, plastic, asbestos cement or fiberglass reinforced epoxy.

Like all other parts of a sewer system, force mains require routine visual inspections and maintenance to ensure proper function and mitigate risks. They are also usually subject to the same modes of failure as conventional gravity lines, including clogs, breaks and leaks, corrosion, age, and more. 


Learn more about Envirosight’s lineup of inspection technology, from the ROVVER X sewer inspection crawler to the SAT II lateral launch crawler:Learn More

Topics: Sewer School

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Envirosight provides video pipeline inspection solutions to municipalities, contractors, departments of transportation, and civil/environmental engineers. Envirosight is committed to ongoing innovation, delivering products that enhance user productivity and inspection detail. Envirosight serves customers through a trained network of regional sales partners who deliver localized support and expertise with rapid turnaround. 


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