Basement Drain Backing Up When Flushing Toilet (Causes And Fixes)

Is your basement drain backing up? We can imagine it’s nothing short of a nightmare. Your drain’s probably backing up because the wastewater has nowhere else to go due to a blockage or issue with the sewer line. There might be other issues at play here as well. This article will explore the different causes of your basement drain backing up and how to fix these issues. 

A basement drain can get clogged up due to the backing up of a washbasin or tub, tree roots, pipe deterioration, and several other reasons. A drain blockage has the potential to destroy your plumbing system. You can fix some of these issues independently like using a plunger or chemical additives, while others may require a professional. 

A backed-up basement drain can be quite an unpleasant experience for a homeowner. The origin of the blockage can be anywhere in the house. However, the backing up may occur at the basement drain because it is on the lowest level. The foul smell and the mess are enough to frustrate anyone. 

There is also the matter of this situation directly impacting your plumbing and drainage system. This issue needs to be remedied immediately. 

However, you don’t always have to spend a ton of money to have most of these issues fixed. Let’s look at some common causes of your basement drain backing up and fixes. 

basement drain backing up

5 Causes & Fixes for a Basement Drain Backing Up 

For several reasons, your basement drain might be getting clogged up and backing up when you’re flushing the toilet. Before you can fix the issue, you need to get to the root cause. 

Area of Blockage Causes 
Main Sewer Line Grease buildup
Undissolved items from flush
Hair, debris, and dirt
Sewer line 

Pipe deterioration 
Tree roots 
Main drain line and basement pipe separated
Freezing temperature
Basement drain Excess water in drain 
Clogged vent pipe 

1. Washtub Basin or Washing Machine 


Many homes have a wash tub basin in the basement. It’s mainly used to soak up clothes or do laundry. Debris or dirt from washing can get stuck in the drain. The same can happen with a washing machine but that will simply block the hose pipe. 

using an electric snake to clean up the pipe
Image from Mville Serv


One solution is to use a plunger to clear out the sediments or the debris. If this fails, use an electric snake to clean up the pipe. A precautionary measure is to install a strainer on the drain so you can avoid debris getting in the first place. If all of this doesn’t work, it’s time to call a professional. 

2. Tree Roots 


Tree roots thrive on moisture and there is plenty of that in the sewer line. They will slowly creep in and continue to do so once they get access to your sewerage system. Their growth can damage your lines and also cause neighborhood wide damage. 


Unfortunately, you will have to call a professional to fix this issue. If you suspect tree roots have creeped in your sewage, you need to call a sewer line inspection company. The procedure can cost up to $300. 

They’ll use a powerful drain cleaning machine to clear the roots and any debris or gunk stuck in the lines. The experts can also give you some tips to prevent this from happening again. This may include you having to move a tree or two. 

3.Pipe Deterioration


Pipes are made up of material that can shrink and rust over time. As they shrink, debris or objects in the water can get stuck in these pipes. Other homes may have clay or concrete piping. These also tend to experience wear and tear over time. 

This one needs professional opinion as well. They should be able to tell you the kind of pipes you have and also recommend a fix.


Depending on the extent of the damage, it may require replacing the pipes or a section of them. The location of the pipes will also determine who manages the repairs as the city may be responsible for replacement in certain areas. These are pipes that originate from the main underground sewage lines and extend beyond your home. 

4. Dip or flat spot 


A dipped or a flat spot can form in your drain line when the ground settles. This can backup your basement floor drain.  


A hydro jet can clear up the pipe but in case of extensive blockage you may need to call in a mini excavator and have the ground dug up and the pipe replaced. 

5. Flushing Undissolvable Objects 


Objects such as toys, feminine hygiene products, napkins, diapers, wipes, etc can get flushed down the toilet. Toilets aren’t designed to drain these objects. Even two-ply tissue paper can get stuck in the drain and cause it to back up. 


The best way is to just prevent throwing such objects in the toilet bowl. If something does get stuck, you can take the water out of the toilet bowl and then your hands or a plunger to remove the object. In some cases, you may have to call the plumber if the damage is beyond your control. 

Prevent Future Back Ups in Your Basement Drain 

Obviously, your main goal after one major blockage should be to ensure it never happens again. Here are a few steps you can take to make sure you avoid the hassle in the future: 

  1. Pay attention to the basement drain. You need to maintain it the same way you maintain all the other drains in the house. Hire a professional to clean and maintain drain on a regular basis. 
  2. You can also use the following method to occasionally clear out any grease or grime buildup: 
vinger and baking soda in two bottoles
  • Take one part baking soda and one part white vinegar 
  • Put this in the drain and cover the drain with a stopper for about 30 minutes to help the foam form and do its magic
  • Take the stopper out after 30 minutes and use a plunger in the drain 
  • After you’re done with taking the clog out with the plunger, add warm water to the drain 
  • If you still feel the clog is there, use the plunger again

Frequently Asked Questions 

How to prevent water coming up from the basement drain 

Installing a reverse valve to prevent water from coming back up the drain. 

Why is the main drain backing up? 

Blockages and clogs are the main reason for the main drain backing up. These clogs can be caused by hair, grease and grime. They can also happen due to sump pump failure. 

How to know if the plumbing vent is blocked? 

A foul smell or gurgling sounds around the house are indicative of a blocked plumbing vent. If this isn’t fixed quickly, sewage gasses can seep around the house and damage your health. 

Final Thoughts 

A basement drain backing up can be quite a frustrating and expensive situation to fix. It is best to take precautions to prevent the back up in the first place. Regular maintenance and some preventive measures will ensure you avoid the hassle of cleaning up the mess from a backed up drain. 

Leave a Comment