What is a Sewer Line Cleanout?

What is a sewer line cleanout? All the drains and toilets in your home or business connect up to a line that runs out to the city sewer system at the street.  Technically it’s called a “lateral,” although some people refer to it as the “main sewer line” even though that term’s best reserved for the city’s main.  While drain pipes in homes are typically 1 1/2 inches in diameter sewer lines are typically 4 inches.  And they can be far larger for commercial buildings.  So it takes a larger diameter cable and auger to clean them.

The larger equipment can’t make sharp bends; they need more direct access.  That could be through a vertical vent but that means going up on the roof.  That could be through a toilet connection, but that means removing the toilet first.  So it’s far better to use something designed exactly for that purpose.

Sewer Line Cleanout

And that something is a sewer clean-out.  They consist of a short pipe that taps into the sewer lateral and is sealed with a screw-off cap.  Made of the same material as the sewer line they’re most commonly cast iron or plastic.  The clean-out cap can be plastic, brass, or cast iron.  They’re often covered with a plastic box or a concrete slab for protection and a better appearance.  That cover can be hinged or simply lift off.

They’re usually located in the yard, usually within around 3 feet of the building foundation.  Or near the property line, often beside a sidewalk.  Or both.  They stick just a couple of inches above the ground so they’re often hidden by vegetation or mulch.  Some homeowners and landscapers hide them with a rock.  And sometimes the clean-out tap is under a concrete cover in the garage.

There can also be clean-outs for a single drain pipe.  These are usually visible on an outer wall and can be made of metal, ABS (black plastic), or PVC (white plastic).

When it’s time for sewer cleaning the cap is unscrewed, with the possibility of an unpleasant back-flow.  In addition to using the tap for cabling (drain snaking) a plumber may also use it as an access point for larger advanced sewer cameras to make a video inspection of the line and/or blockage.


  • Newer homes usually have a sewer clean-out, but older homes may not.
  • Since they can be hard to find you can save time and expense by finding yourself it ahead of time.
  • The cap can be jammed so tightly that it simply can’t be opened.  If that’s the case or there’s no clean-out, it’s usually worthwhile to have one installed.  That makes the present sewer cleaning go better and can be a big dollar saver for future problems.  It also brings the lineup to code for any future home sale.
  • There are actually two types.  A single clean out is a fitting shaped sort of like a “Y” with the tap coming off at about 45 degrees.  That allows inserting a cable or camera in one direction.  A double cleanout looks more like a “U,” which has two caps, and allows access in both directions.