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A renovated bathroom with vanity, fixtures and tile
A renovated bathroom with vanity, fixtures and tile.

The Manual: Drains

Main Drain Backup in Toronto

When the lowest drain in the house starts filling up instead of emptying, you are looking at the main line. Act fast and act in order.

  • Floors protected and the work area left tidy
  • A written note of what changed and why
  • Shut-off help by phone before the truck arrives
  • The real cause pinned down ahead of any cutting

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Signs you need this fixed

  • Water standing in the tub after a shower
  • Gurgle from the sink when the toilet flushes
  • Sour smell from the overflow or the trap
  • Washer drain spitting back up the standpipe

Is it the main or one fixture?

A single slow fixture is a branch problem. A main drain problem shows up everywhere at once, starting at the lowest point. Look for these clues:

  • Water or sewage appearing at the basement floor drain.
  • The basement toilet bubbles when an upstairs sink drains.
  • Every fixture in the house slows down on the same day.
  • Washer water spills from the standpipe as the machine drains.

If only one fixture is slow, read our drain cleaning page instead.

Stop using water: why it matters

Everything that goes down any drain ends up at that same blocked spot. With the main closed, it has nowhere to go but up the lowest opening, which is usually the basement floor drain. Stop the washer and dishwasher, do not flush, and ask everyone to stay out of the shower. Even a single bath can push several hundred litres of water onto your basement floor.

Got a backwater valve? It keeps the City sewer out of your house, but it cannot help a blockage inside your own line. Water from your fixtures still has to get past it.

Clearing from the cleanout

Most Toronto houses have a cleanout near where the main leaves the foundation. It may be a brass plug in a floor-level fitting, or a Y-fitting with a cap on the stack. We crack it slowly with containment in place, because a loaded line can blow water out hard. Then a sectional machine with a cutting head goes in toward the street. Roots, wipes, grease and scale are the usual finds. Once flow returns, we run water for several minutes to flush the line.

Camera check before you sign off

Clearing a main tells you nothing about why it blocked. A camera run, done right after cleaning while the line is open, shows roots at joints, offsets, bellies where the pipe has sagged, or a collapse. It also reveals whether the stoppage sat beyond your lot line. We review the footage with you and give you a copy. That way you are not paying to clear the same line next spring without knowing why. See sewer camera inspection.

What is included on the visit

Tools on the truck

  • Drum machine with 3/8" cable for trap arms and stacks
  • Jetter with a rear-firing nozzle for grease
  • Drop-head hand auger for sink and tub branches

What we open

P-trap, cleanout plug or the floor drain grate

How we test it

Fill-and-drop test on every fixture on the branch

How the job runs

  1. Ring the line

    Say what is dripping, backing up or banging. Water still flowing? We guide your hand to the valve first.

  2. Find the cause

    The plumber traces the fault, with a scope or gauge where one earns its keep.

  3. Pick the fix

    Options come in everyday language, and nothing starts until you choose.

  4. Repair & prove it

    We finish, run the water to prove it, wipe up and leave a short written record.

Calls we field, answered plainly

Who pays if the blockage is under the street?

When footage puts the fault under City land, Toronto Water takes it from there. Call 311 with the footage or our notes.

Is sewage backup covered by insurance?

Often only with a sewer backup endorsement. Check your policy wording before you need it.

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