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Is the City or Homeowner Responsible for a Main Drain Blockage?


plunger in sink with blocked main drain

Determining responsibility for a main drain clog can be a complex issue, with various factors like local regulations and specific circumstances to consider. Here’s a short guide on how to find out who’s responsible.


When is the City Responsible?

The city is responsible for maintaining and fixing the pipes that go from a home’s property line to the municipal water main and sewers. For example, if a blockage occurs because of root intrusion in the public sewer line, the city is liable.


When is the Homeowner Responsible?

The pipes that run from a home’s property line into the home are the homeowner’s sole responsibility. For example, if a blockage happens because the homeowner improperly disposed of an object, grease or other material, they’re responsible for the cost of clearing it.


Reasons Sewer Backups Occur

The most common causes of main drain line blockages include:

  • Pouring fat, oil and cooking grease down the drain. When these substances are poured down the drain, they cool, harden and stick to the inside of the pipes, resulting in blockages.

  • Flushing baby wipes down the drain. Unlike toilet paper, baby wipes aren’t designed to disintegrate in water. Over time, they can accumulate in your pipes, causing clogs.

  • Disposing of sanitary items and dental floss down the drain. Sanitary items, such as tampons and pads, as well as dental floss, don’t break down in water. When flushed down the drain, they can obstruct your pipes.

  • Overgrown roots from nearby trees. Tree roots are naturally drawn to water sources, including the moisture in sewer lines. As the roots grow, they can enter small cracks or joints in the pipes, gradually expanding and causing blockages.

  • Heavy rain. During periods of heavy rain, the sewers can sometimes become full, causing backups.

  • Old, cracked sewer pipes. Over time, pipes can break down and crack, especially those built in older homes that may contain cast iron or clay.


The best way to prevent a main drain blockage and avoid having to pay out of pocket to have it cleared is by investing in regular maintenance. At Black Forest Plumbing, we offer professional sewer line and drain cleaning services to keep your water flowing. We use specialized equipment, such as a drain camera, to swiftly diagnose and fix issues so you don’t run into any problems.


Main Drain and Sewer Line Backup Services

If your main drain is blocked, the team at Black Forest Plumbing can help. We offer professional drain clearing services for residential property owners across the Greater Toronto Area including Barrie, Newmarket and Aurora. Contact us for more information or to book a service call.

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