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Common Causes of A Sewer Blockage and How to Prevent Them

A sewer blockage can be one of the most distressing and unpleasant plumbing problems for homeowners. Not only can they cause extensive damage to your property but they can also pose significant health risks. Understanding the common causes of sewer blockages and knowing how to prevent them can save you from these headaches.

Common Causes of A Sewer Blockage

  1. Tree Root Infiltration
    • Description: Tree roots naturally seek out water sources, and your sewer line can be an attractive target. Roots can infiltrate and grow inside the pipes, causing blockages and breaks.
    • Signs: Slow drains, gurgling noises from toilets, and lush patches of grass over your sewer line.
  2. Clogs
    • Description: Common household items like grease, hair, and non-flushable products (e.g., baby wipes, feminine hygiene products) can accumulate and cause severe clogs in your sewer line.
    • Signs: Multiple drains blocking up simultaneously, slow drainage, and unpleasant odours.
  3. Aging Sewer Systems
    • Description: Older homes may have outdated sewer systems made from materials like clay or cast iron that are prone to deterioration over time.
    • Signs: Frequent backups, leaks, and sewer line collapses.
  4. Heavy Rainfall and Flooding
    • Description: Excessive rainfall can overwhelm the municipal sewer system, causing water to back up into residential sewer lines.
    • Signs: Blockage during or after heavy rains, water pooling in the basement, and sewage smell.
  5. Broken or Collapsed Sewer Lines
    • Description: Shifting soil, construction work, or wear and tear can lead to broken or collapsed sewer lines.
    • Signs: Persistent blockages, unusual lushness in certain areas of your yard, and sewage leaks.

How to Prevent A Sewer From Blocking

  1. Regular Maintenance
    • Action: Schedule regular inspections and cleaning of your sewer line by a professional plumber.
    • Benefit: Early detection and removal of potential blockages before they become serious problems.
  2. Proper Disposal Practices
    • Action: Avoid pouring grease down the drain and dispose of non-flushable items in the trash.
    • Benefit: Reduces the likelihood of clogs forming in your sewer line.
  3. Tree Root Management
    • Action: Plant trees away from sewer lines and consider removing trees that pose a threat to your pipes.
    • Benefit: Prevents roots from infiltrating and damaging your sewer line.
  4. Upgrade Your Sewer Line
    • Action: If you have an older home, consider upgrading to modern, durable materials like PVC.
    • Benefit: Reduces the risk of breaks and collapses in outdated pipes.
  5. Install a Backwater Valve
    • Action: Install a backwater valve to prevent municipal sewage from backing up into your home.
    • Benefit: Provides an extra layer of protection against sewer backups during heavy rains or flooding.
  6. Water Usage Management
    • Action: Spread out water usage to avoid overwhelming your plumbing system (e.g., don’t run the dishwasher and washing machine simultaneously).
    • Benefit: Prevents overload and reduces the risk of sewer blockages and backups.


A sewer blockage can be a major inconvenience. It can be costly to fix. However, understanding their common causes and taking proactive measures can significantly reduce your risk. Regular maintenance, proper disposal practices, and strategic upgrades to your plumbing system are key steps in safeguarding your home. By being vigilant and proactive, you can prevent the costly and unpleasant experience of your sewer being blocked. For more personalised advice and professional plumbing services, don’t hesitate to contact your trusted Pro Plumber.