What is the most common cause of sewer backup?
Blockages in the line are the most common cause: tree roots, grease, flushed wipes and debris, or a collapsed or sagging section. Heavy rain can also overload the municipal sewer and push wastewater back toward homes. Often the cause is on your own lateral, but not always.
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Common causes
- Tree roots entering joints in old clay or cast iron pipe
- Grease, fats and food scraps that harden in the line
- Wipes and other items that should not be flushed
- Collapsed, cracked or sagging pipe sections
- Heavy rain overloading the municipal sewer
- Blockages in the City main
Scarborough streets and older pipes
Many Scarborough streets were built in the postwar decades, and mature trees now grow over lateral lines that have aged. Roots seek out the moisture at joints and grow inside, catching paper and debris. A storm adds volume to a sewer that may already be near capacity.
Homes with basement apartments put more fixtures on one line, which makes blockages show up faster.
How to reduce the risk
Put grease in the trash, flush only toilet paper, have a plumber camera the line if you have had slow drains and ask about a backwater valve, which a licensed plumber installs. These steps lower the chance but do not eliminate it.
How a camera inspection helps
A plumber can feed a camera through the line to see roots, cracks, sags and buildup. The footage shows where the problem is and whether a repair or a replacement is needed. It also gives you a record for your insurer or the City.
Ask for the video, and keep it with your home records.
If it already happened
A plumber finds the cause. If the blockage is in the street, the City handles it. Our sewer backup service in Scarborough cleans and dries the basement, and our basement flooding service applies to larger events. We write down the drains involved and the timing, which helps the plumber and your insurer. Your insurer decides what your policy pays; we bill them directly where allowed. The assessment is free, and a written scope and price come first.
Related questions
Is a sewer backup always my fault?
No. It can come from the municipal main as well as from your own line.
Can a plumber prevent the next one?
A plumber can clear the line, repair damage and fit a backwater valve.
Do wipes labelled flushable really go down?
They often do not break down and are a frequent cause of blockages.
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