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Signs Your Main Drain And Sewer Line Needs Repair

Technician inspecting a home’s main drain line and plumbing stack.

Main drains and sewer lines do a lot of work in a home, but most people do not think about them until something goes wrong. In Toronto, backups often occur at the worst times, such as during laundry, morning routines, or wet weather that increases demand on your drainage system. This guide covers common warning signs, how to tell a clogged main drain from a sewer line issue, and what you can check safely at home.

If symptoms keep returning, AtlasCare can help with drain cleaning, sewer line repair, and drain camera inspection. If you need plumbing services in Toronto for a recurring main drain issue, early diagnosis is usually the fastest way to stop repeat backups.

What Is The Difference Between A Main Drain And A Sewer Line?

Main drain (inside): The primary pipe inside your home that collects wastewater from sinks, showers, tubs, and toilets before it exits the building.

Sewer line (outside): The underground pipe (often called the sewer lateral) that carries wastewater away from your home to the municipal sewer system. Homes on septic have a similar buried line that carries wastewater to the septic tank/system.

A clog inside the home can cause slow drains and gurgling. A blockage or damage outside can cause wider backups and sewage odours because there are fewer places for sewage to go.

What Are The Most Common Signs Of A Clogged Main Drain?

Main drain issues often start small and get worse over time. Common signs include:

  • Slow drains in more than one fixture (for example, a shower and sink).
  • Gurgling or bubbling sounds from a sink, tub, or toilet
  • Water backing up in a lower fixture, like a tub or basement floor drain
  • The basement floor drain is pooling after you run water elsewhere

If these symptoms repeat, it is usually time to stop guessing and book professional drain cleaning.

What Are The Warning Signs Of A Sewer Line Problem?

Sewer line problems often show up as “whole-house” symptoms, not just one slow sink:

  • Sewage odours indoors or outdoors that persist
  • Multiple fixtures are backing up at the same time
  • Sewage backup into a basement drain, tub, or shower (treat this as urgent)
  • Wet patches, soft ground, or sunken/depressed spots in the yard, especially with odours

In Toronto, sewer service lines are owned by both the City and the property owner: the City-owned portion runs from the sewer main on the street to the property line, and the privately owned portion runs from the property line into the home, so early diagnosis matters.

Is It A Clogged Main Drain Or A Clogged Sewer Line?

Rule of thumb:

  • A single fixture usually points to a local clog (a trap or branch line).
  • Multiple fixtures, lower-level backups, and sewage odours often point to a main drain or sewer line issue.

The fastest way to confirm the cause is usually a drain camera inspection, so you are not paying for repeated temporary fixes.

What Causes Main Drain And Sewer Line Clogs?

Common causes include:

  • Grease and fats that cool and stick inside pipes
  • Wipes, paper towels, and hygiene products (even “flushable” ones)
  • Hair and soap buildup
  • Food scraps in the kitchen lines
  • Tree roots (a common sewer line issue)
  • Pipe defects, like cracks, offset joints, or a sagging section, where debris collects

What Can I Safely Check At Home?

Keep it simple and safe. These checks can help you decide whether you need a plumber in Toronto urgently.

Homeowner OK

  • Stop running water if you see an active backup.
  • Check whether more than one fixture is affected.
  • Think about what happened right before the issue (grease disposal, wipes, a large laundry load).
  • Keep floor drains clear and accessible so you can monitor changes.

Pro Only

  • Snaking main lines, hydro jetting, or opening cleanouts (higher exposure risk if done incorrectly)
  • Drain camera inspections to confirm roots, cracks, or collapsed sections
  • Repairs involving excavation, lining, or pipe replacement
  • Sewage cleanup beyond very minor surface cleanup (follow public health guidance)

If you suspect sewage contamination, avoid DIY cleanup beyond basic safety steps and contact a professional.

When Is It Time To Call A Professional Right Away?

Call for help promptly if you notice:

  • Sewage backup in a basement drain, tub, or shower
  • Repeated backups that return after plunging
  • Multiple fixtures are backing up at once
  • Strong sewage odours that persist
  • Wet yard areas paired with indoor drainage problems

In these situations, a technician can diagnose the cause and recommend the safest next step, whether that is drain cleaning, sewer line repair, or emergency plumbing help.

What Happens During A Drain Camera Inspection?

A camera inspection helps remove guesswork. A technician sends a small camera through the line to locate the blockage or damage and confirm the cause of the symptoms, such as root intrusion, a cracked section, or a sagging area. Based on what the camera shows, they can recommend the most appropriate next step, whether that is targeted clearing, repair, or replacement.

If you are seeing mainline warning signs, book a drain cleaning or a sewer line inspection with AtlasCare. For plumbing services in Toronto, an early diagnosis can help prevent repeat backups.