Short answer
Sewage coming up through the basement floor drain means the blockage sits in the main line, downstream of every fixture in the house. The floor drain is the lowest opening, so it fills first. Stop running water and get the line cabled and then camera'd, because the camera is what tells you whether this is a one-time clog or a defect in the pipe. A line that backs up again within weeks of a clearing has a flat spot, roots or a broken section, and no amount of cabling fixes that.
Tell a one-time clog from a broken line
- Stop using water. Every flush, shower and wash cycle adds to what comes up at the drain.
- Look into the floor drain. Standing water or sewage in it puts the blockage past that point, out toward the street.
- Run one fixture at a time. If a single sink drains fine and the floor drain still rises when you flush a toilet, the main line is the problem.
- Find the main cleanout. It is a capped fitting, usually in the basement floor or wall, or in the yard near the foundation.
- Check the lower walls around the drain. Staining, a tide line or flaking paint means this has happened before, whatever you were told.
- Have the line cabled, then ask for a camera run down the same line afterward.
If the line clears and stays clear for months, it was a clog and you are done. If it backs up again, or the camera shows roots, a flat spot or a break, the pipe itself needs repair.
Repair or replace
| Situation | What to do |
|---|---|
| First backup, no history of it | Cable the line. Ask for a camera run after, so you know what caused it. |
| Backs up again within weeks of a cabling | Camera the line before paying for another cabling. Repeat clogs mean a defect, not habits. |
| Camera finds roots at a joint | Repair. Cut the roots, then spot-repair or line that joint so they cannot come back. |
| Camera finds a flat spot or belly | Repair that section. A bellied run holds waste and clogs again, and cabling never levels a pipe. |
| Camera finds a collapsed or offset pipe | Replace that run. Dig-and-replace or pipe-bursting, depending on what is above it. |
| Old clay or cast iron lateral, several defects along the run | Replace the lateral rather than repair it in three places. |
| Sewage marks on the basement floor or lower walls | Clean and disinfect the area first, then fix the line. Hire for this. |
| Backup happens only during heavy rain | Ask the plumber to check for storm water getting into the sanitary line. |
Can I do it myself?
No, not once it reaches the floor drain. A plunger or a hand auger clears one fixture, but a main-line blockage sits past every fixture and 25 feet of hand auger will not reach it. Clearing a main line takes a power machine fed through the cleanout, and a camera to see what it found. Raw sewage also carries bacteria that a wet vac and household cleaner do not handle.
Hire for this, and stay out of standing sewage without boots and gloves.
What a contractor will ask you
Have these ready and you skip the back-and-forth.
- Where it comes up. The basement floor drain, a cleanout, a shower or a toilet. Name the lowest one.
- A wide photo of that area, including the surrounding floor and the lower walls, not a close-up of the drain.
- Any signs of past intrusion. Staining on the floor or lower walls tells the plumber this is not the first time.
- Whether a camera has already been down the line, and the report if one exists.
- What the camera found, in the inspector's words, such as a flat spot, roots or an offset joint.
- The age of the house and the lateral, and whether the line has ever been cabled or repaired.
- Where the cleanout is, inside or in the yard, and whether it is reachable.
Last reviewed .