How Drains and Sewer Lines Work

The parts, in order

1. 1 Fixture drain and trap. The curved trap under a sink holds a little water that blocks sewer gas from coming back up.
2. 2 Branch lines. Pipes in the walls and floors that carry water from each fixture.
3. 3 Vents. Pipes that run up through the roof and let air into the system so water drains smoothly.
4. 4 Main drain or stack. The larger pipe the branches join inside the house.
5. 5 Cleanout. A capped opening that gives access to the main line for cleaning and camera work.
6. 6 Sewer line. The buried pipe that carries everything from the house to the public sewer.

Where clogs form

Small drains usually clog close to the fixture: hair in a tub, food and grease in a kitchen sink. The main line usually stops because of roots, buildup inside older pipe, a sag or offset in the line, or things that shouldn't be flushed.

• One slow fixture: most likely a branch or the fixture itself.
• Several fixtures slow at once, or water coming up in a floor drain: most likely the main line.

How each problem gets cleared

• Small drains are cleared with hand tools or a small cable.
• Main lines are cabled (snaked) to clear a stoppage, or hydro jetted to scour buildup off the pipe walls.
• Old cast-iron lines heavy with scale can be descaled with a carbide chain.
• A camera inspection shows the inside of the pipe: roots, scale, offsets, breaks or sags.

• Drain cleaning
• Main sewer line cleaning
• Hydro jetting
• Sewer camera inspection

When cleaning isn't enough

If the camera shows a break, collapse or serious defect, cleaning only buys time. Depending on what it finds, the options can include a spot repair, a point patch, lining or replacement. Not every line qualifies for every option, and the camera inspection is what decides.

• Sewer line repair
• Trenchless sewer repair
• Sewer line replacement