Every drain is slow. That is the main line, and it is warning you.
A main line that is slow today backs up tomorrow, and a backup is sewage on the floor. Cut water use and get it cleared before that.
What is probably happening
- The main sewer line is partly blocked by roots, grease or a sagging section.
- Gurgling in a tub or floor drain when the toilet flushes is the classic sign.
- If the lowest drain in the house is already holding water, you are hours from a backup. Treat it as one.
Do this in the next five minutes
- Cut water use. Short showers, no laundry, no dishwasher until it is cleared.
- Find the cleanout, a capped pipe outside near the foundation or in the basement. The plumber will need it.
- Look at the lowest drain. If water is standing in it, stop using water entirely.
- Note whether it got worse after heavy rain. That points at the city main or roots.
Do not
- Do not pour drain cleaner into a main line. It cannot reach the blockage and it hurts whoever opens the line.
- Do not remove the cleanout cap indoors if the line is full. It will come out at you.
- Do not sign a sewer replacement until you have seen the camera video.
Who to call
A licensed plumber with a main line machine and a camera
A main line needs a full size auger or a jetter and a camera to find the cause. That is a plumber, not a handyman.
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What it should cost
$99 to $1,600, averaging $380
Clearing a main sewer line clog. Snaking $100 to $250, hydro jetting $350 to $600, camera $200 to $1,300
Source: Angi, main sewer line clog repair cost, updated July 2026. View source
National published range, not a quote for your job. The full cost table for this trade is on the plumbing page.
Ask this contractor, on the phone, before anyone comes out
Tap each one as you ask it.
- Will you camera the line after clearing, and can I keep the video?
- Roots, grease, or a break? What did the camera show, and where?
- If it is roots, what is the maintenance interval and cost to keep it clear?
- If you find a break, will you mark the spot and depth on the surface before quoting?
End the call if
- A dig or lining quote with no video for you to see.
- A plumber who clears it and refuses to camera it.
- Pressure to sign a replacement contract that night.