Drain Cleaning
Main sewer line cleaning
Short answer
Main sewer line cleaning clears the single pipe that carries all of a home's wastewater to the city sewer or septic tank. It's needed when several drains slow or back up at once, especially the lowest fixtures. A plumber clears it from a cleanout with a large cable machine or a hydro jetter, then often runs a camera to find out why it clogged.
Updated · Prepared by the Plumb Right Now editorial team
Main Sewer Line Cleaning at a glance
- Classic sign
- Water comes up in a tub, shower or floor drain when a toilet flushes or the washer drains.
- Access point
- A sewer cleanout: a capped pipe outside near the foundation or in the basement.
- Common causes
- Tree roots, grease, wipes, a sagging section, or a broken or offset pipe.
- Often followed by
- A sewer camera inspection to see what caused the blockage.
Main line or a single drain?
Every sink, tub, toilet and floor drain feeds a branch line, and the branches join the main line on its way out of the house. A clog in a branch affects one fixture or one bathroom. A clog in the main affects everything downstream of it, which is why the lowest drains in the house, usually a basement floor drain or a first-floor tub, are the first to back up.
A quick test: run water in an upstairs sink for a minute and watch the lowest drain. If water rises there, or a toilet gurgles when the washing machine drains, the blockage is almost certainly in the main.
How plumbers clean a main sewer line
| Method | What it does | Best for |
|---|---|---|
| Cable machine (sectional or drum) | Spins a cutting head through the blockage | Opening a full blockage; cutting roots |
| Hydro jetting | Scours the full pipe wall with high-pressure water | Grease, scale, recurring clogs in sound pipe |
| Camera inspection | Shows the cause and the pipe's condition | Deciding whether cleaning is enough |
Jetting is usually done only after a camera confirms the pipe can take the pressure.
What happens during the visit
Find the cleanout
The plumber locates the main cleanout. If there isn't one, access may be through a toilet flange or a roof vent, or a cleanout may need to be installed.
Clear the line
A cable or jetter opens the blockage; the plumber runs water to confirm full flow.
Look inside
A camera run shows roots, sags, breaks or buildup and their distance from the cleanout.
Decide next steps
A one-off clog may need nothing more. Roots or a broken pipe point to sewer line repair or trenchless repair.
When cleaning isn't enough
If the main needs clearing more than once or twice a year, something structural is usually behind it: roots entering through cracked joints, a belly where waste settles, or a pipe that has partly collapsed. Cleaning restores flow but doesn't fix the pipe, so recurring clogs are the point to ask for camera footage and a repair estimate rather than another cleaning.
Related to main sewer line cleaning
Common questions
Will cleaning the main line get rid of a sewer smell?
Only if the smell comes from waste sitting in a partly blocked line. If drains run freely and it still smells, a dry trap or broken vent is more likely; see why drains smell.
Where is the main sewer cleanout?
Usually a capped pipe a few inches across, outside near the foundation, in a basement or crawlspace, or in a garage. Some older homes have none.
Should I use a chemical cleaner on a main line clog?
No. Chemicals rarely reach a main line blockage and leave caustic water for whoever opens the line.
Is hydro jetting better than snaking for a main line?
Jetting cleans the whole pipe wall and lasts longer on grease and scale; snaking is better for opening a full blockage or cutting roots. Many jobs use both.
Why does my main sewer line keep clogging?
Roots, a sag where waste settles, grease buildup or a broken section. A camera inspection shows which.
Can I keep using water while the main is clogged?
Avoid it. Every flush or load of laundry adds water that has nowhere to go but the lowest drain.
Who is responsible for the main sewer line?
Usually the owner, from the house to the public sewer connection; some cities own part of it. Check with your sewer utility.
What if my home has no sewer cleanout?
The plumber may work through a toilet or vent, and often recommends installing an exterior cleanout for future access.
Does main line cleaning remove tree roots for good?
No. Cutting roots restores flow, but they grow back through the same cracks; lining or replacing the pipe is the permanent fix.
Do I need a camera inspection after main line cleaning?
It's worth it when clogs repeat, the home is older, or roots were found, because it shows whether the pipe needs repair.