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8 Most Common Causes of Smelly Drains and How to Fix Them

Ah, the smell of household drains is something we all dread. Most of the time, the smell comes from the pipes. A block in the toilet can result in a foul odour. Fortunately, many bathtub and sink drains have simple mechanisms that can easily clear using everyday household items.

To start, here are the various possible causes of smelly drains that you need to know about: 

Tree Roots 

Overgrown tree roots can cause blockages and smells. If they are the main cause of the problem, you’ll likely experience gurgling sounds, raw sewage appearing from the pipes and prolonged toilet flushing.


A dodgy pipe is a common cause of smelly drain, especially if you have an old house. Back in the day, pipes were made with clay and cement, which were not crack-proof. Therefore, slight movements underground can cause damage that will lead to blockages. 

Drain Flies

It’s probably the first time you read about drain flies, but they do exist and love drains. Even though they’re small, they can cause unpleasant smells. 

Blocked Vent 

Your plumbing vent is important because it allows fresh air into the drain and ensures water runs efficiently through the pipes. However, the sewer gases can move into the house if it’s blocked, leading to foul odours. 

Greasy Drain 

Almost every homeowner is guilty of flushing down greasy materials down their drains. It’s never recommended to flush down grease or oil into the drain because they can solidify in the drain pipes and gradually decompose. This can result in a foul smell that can make its way through your house. Moreover, grease can also cause blockage in the drainage pipes. 

Unused Drain

If you haven’t used your drain pipes for a while, they could stink. The trap inside the drain line is responsible for trapping and blocking sewer smells. When you haven’t used the sink for a while, the water from the trap evaporates and will allow that sewer smell to make its way into your house. 

Food Particles

Getting rid of food waste through the garbage disposal can get food debris stuck in the drainage pipes. 

Dirty Garbage Disposal

Your garbage disposal should be cleaned regularly to get rid of food debris that may cause foul odours. 

How to Fix Your Smelly Drain Problems

Now you know the common reasons behind a smelly drain, there are several things you can do to solve the issue. The first thing and probably the easiest is to run the garbage disposal if the smell is coming from the kitchen drain. Run your kitchen tap for a few seconds and turn on the garbage disposal while you let the water run for 10-15 seconds. 

Another easy way to solve smelly drains is to use baking soda. All you need to do is pour some baking soda down a blocked or smelly drain, then follow it up with plain white vinegar. Block the drain tightly and wait for a few seconds. 


It’s pretty easy to remove blockages that may cause your drains to smell. However, if you can’t get rid of the foul odours from your drains using the steps above, maybe it’s time to hire a professional plumber to have your plumbing system checked. 

Sunny Coast Plumbing & Gas offers a 24-hour plumbing service. We handle any plumbing issues, including blocked sinks, water leaks and sewer repairs. Contact us for your emergency plumbing needs! 

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