4 Common Causes of Sewer Drain Clogs

Sometimes, drain blockage issues in your home are not located within your home. If you find that multiple areas in your home are experiencing drainage issues, there might be something wrong with your main sewer line.

So, what exactly causes sewer drain blockages?

  1. Tree root intrusions

When the weather is dry, tree root intrusions are a common problem. Roots of large trees like to seek for moisture and nutrients. Since your pipes hold moisture and minerals, they tend to seep through small cracks in the pipes and grow in and around the pipes. Eventually, they grow to fill the pipes, causing complete blockages.

  1. Pipe damage

Broken, ruptured and collapsed pipes tend to lead to frequent backups. Especially in older homes where pipes are made from cast iron or clay, which tend to break down over time due to corrosion.

  1. Sagging sewer line

Sags are usually caused by shifting soil, particularly under the weight of houses. Sagging sewer lines cause ‘bellied’ pipes which prevent wastewater from being properly flushed out of the sewer line, resulting in blockages.

  1. Flushing the wrong things down the toilet

There are certain things you shouldn’t be flushing down the toilet. These include: wipes (including flushable wipes), baby tissues, hair, napkins, tampons and plastic bags.

  1. Grease build-up from drains

Common sink blockages occur due to pouring grease down the drain. Kitchen sink blockages are mainly caused by this, but sometimes they can build but further down the pipes, into the main sewer line.


While some of these issues are out of your control (and should be treated with by a professional plumber who has the right equipment and experience for the job), others are completely within your control. Make sure you are doing all that you can to prevent these blockages from occurring in your home.