What Causes Sewer Backup and How to Fix It?

A sewer backup is one of the most annoying plumbing issues for every homeowner. If you’ve ever dealt with them, you can attest that they’re the most disgusting and messy thing to happen. 

However, because they’re common in our homes and you can’t ignore them, you need to know how to prevent sewage backup in house and to keep away from a messy situation.  

Just in case if you have never handled a backup of sewer and drain before, then how to manage it? Don’t worry; you don’t need to have any experience to handle a sewer backup. This article will guide you step by step to know;

  • What a sewer backup is
  • What causes drains to backup and,
  • How to prevent sewage backup in house.

Now, let’s dive in,

What is a Sewer Backup?

A sewer backup is flooding faced at home. It’s caused by municipal/ city sewage system overflow. It occurs due to the movement of the wastewater in the wrong direction via the sewer system. 

The dirty water mostly flows into your house via the sinks, toilets, and drains instead of flowing down them.

What Causes Sewer Backup?

Below is the list of the significant sewer backup signs in your home:

01. Clogs

Toilet Clog

Are you hearing some gurgling noises after flushing the toilet? Or is the water taking too long to drain from the sink? If yes, then you might have got a clogged drain. The abnormal functioning symbolizes clogs in the drain.

With time, the clogs develop, blocking the liquid from freely flowing out of drain pipes, affecting the effective functioning of the toilets, sinks, showers, dishwashers, washing machines, and also the sprinkler system.

If it’s a severe clog, the raw sewage would push back into your drains and then up into the plumbing pipes from the main sewer line or septic tank. The following are the significant causes of drain clogs;

  • Hair
  • Hardened Grease
  • Cotton Swabs and Dental Floss 
  • Paper Towels and Extra-Thick Toilet Paper
  • Baby Wipes and Feminine Hygiene Products

If possible, you should never allow them to enter your drains. Instead, you can put them in a different garbage bin.

02. Plants Roots

Tree Roots in Sewer Line

Plant roots are another common cause of sewer backup. Sometimes, plants roots can find their way into your pipes or even wrap around them. This would result in crushing the lines, especially if they were in poor condition. This process is called root invasion.

Root invasion mainly occurs due to small cracks or holes in the pipes transporting water. The small cracks or holes allow the plant roots to enter the lines when looking for moisture, causing blockages. 

To prevent this from happening, you should consider the trees’ root growth before planting trees in your home. 

03. Blockages of Sewer Mains

Sewerage Main Blockage

Blockage of the main sewer line is another leading cause of sewer backup. The blockage occurs due to clogs that build up with time in the main sewer line. It happens like any other typical clogs you experience in your home. 

They’re majorly caused by inadequate system capacity, especially if the area you live in has heavy growth. The blockage may simultaneously affect all your plumbing in the whole house instead of affecting one drain. 

In this case, you’re advised to shut all your house water supplies off and cover the drain opening with a heavy cloth material that can soak up the water.

04. Sanitary Main

Sometimes, a blockage can happen in the city sanitary main, and if not noticed in time, sewage from the main could back up into your home through floor drains. The good thing is that this occurs gradually, giving you time to assess the damage with a licensed plumber. 

In case the water entering your basement is rapid, it would be advisable to call the office of the city public works to report the issue ASAP for the city operators to investigate.

05. Water in the Basement

Basement Sewer Backup

What causes sewer backup in basement? Well, not every time, the cause of the basement flooding is associated with the sanitary sewer system. In most cases, when the soil settling adjacent to your home is not corrected, it may lead the flowing rainwater towards your home.

If your house has cracks in the floor slab or the foundation, the water will enter your home, causing a flood. You should ensure that water drains away and seal your basement to curb this problem.

How to Fix Sewer Backups?

01. Use a Plunger for Sewer Backup Prevention

Use Plunger to Fix Sewer Backup

Plunger is the easiest and available drain opener around. When sewage backup in toilet, mostly it should be your first choice. If the clogs are medium-sized, using a plunger would go a long way. It provides a quick job on any drain, including sinks and toilets. 

02. Use of Liquid Drain Cleaner

Use Drain Cleaner to Fix Sewer Backup

If you’d like to unclog a bathtub or sink, liquid drain cleaners would come in handy. However, avoid using them to unclog toilets as they eat through the toilet’s wax seal on the toilet bottom, causing leaks. 

03. Release the Pressure

How is it done? First, look in your yard for a cleanout line (a short white pipe of 3-4 inches round sealed with a screw-on cap) and remove the lid. After removing the cup, the sewer line pressure will release, forcing any backed-up water in your home to drain.

04. Use of Chemical Drain Cleaners

Root Killer

Chemical drain cleaners go a long way in unblocking clogs caused by tree roots. A tree-killing foam with herbicide dichlobenil is highly recommended in unclogging toilets. It kills a tree root within a few hours after sticking on it.

05. Water Jet Cleaning of Drain

Water Jet Cleaning of Drain

This method helps clean both medium and severely clogged drains. The high-pressure water jet blows the plant roots down the sewer line. 

06. Augers

Auger Drain Cleaning

Are you looking for the perfect way to clear the clog in your pipes? Then augers will give you the desired result. They work by twisting and cutting clogs that might be further down in a line.


A sewer backup isn’t an issue to be lightly handled as it can lead to the destruction of your valuables, electrical malfunctions, and diseases. So, quick action should always be taken whenever a sewer backup issue arises to avoid all these predicaments. 

How do you deal with a sewer backup in your basement? You can leave a comment in the comment box below.

And before you go, don’t forget to read below article:

How to Unclog a Drain – Its Causes & Remedies

Image Courtesy: Image 4Image 5, Image 8, Image 9

Author Bio

Fidelis Kinai – Fidelis Muti possess a bachelor’s in English and Journalism and have over four years of professional experienced writing and proofreading materials for print and online platforms, including newspapers, magazines, websites, blogs, and social media accounts. He also have over three years of experience as a marketing assistant and social media manager.

He is versatile and diligent and will produce exemplary content within time to meet your deadline.

He can deliver most work within 2-3 days; rush orders are accepted whenever possible. He is based in the Kenya but travel often and work for clients all over the world.

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