What Is a Force Main?
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Quick answer
A force main is the pressurized pipe that carries wastewater from a lift station's pumps to the sewer or septic system. Unlike a normal gravity sewer line, it is pushed by the pumps and can run uphill.
A regular sewer line works because water runs downhill. A force main is different. It is the pipe a lift station pushes wastewater through, so it can climb a rise or travel a distance.
How does a force main work?
When a pump in the wet well starts, it forces wastewater into the discharge piping and along the force main to its destination, which might be a gravity sewer, a manhole or a treatment system. A check valve usually keeps the water from flowing back into the wet well when the pump stops.
What can go wrong with a force main?
- A leak, which can show up as a wet or soft area on the ground along the pipe
- A blockage that makes pumps work harder and cycle more
- A failed check valve that lets water flow back into the chamber
- Air in the line, which can reduce flow
Problems along the pipe can look like pump problems, so we check both. See our lift station pump repair page and our sewer repair service.
Related septic terms
Quick questions and answers
- Is a force main the same as a sewer line?
A force main is a kind of sewer line, but it is pressurized by pumps instead of running by gravity.
- How do I know if my force main is leaking?
Look for wet, soft or unusually green ground along the pipe route, odor, or pumps that run more than they should. Call us to check.
- Who repairs force mains?
Call 832-789-5357 and tell us what you see. We will look at the station and the line and explain the options.
Related guides and services
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