Basement Drain Smells like Rotten Eggs: Causes and Solutions

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We have all come across a bad smell inside our basement. The basement is a place where you can’t find much fresh air since most of the basements are built without windows or patio doors.

That’s why any odor or strange smell is easily noticed inside the basement. Anyhow, it is a common thing to catch a rotten egg smell that comes from your basement.

If that’s the case, you are experiencing a gas leak that comes from your sewer line.

So, let’s see more about this.

basement drain smells like rotten eggs

Why does your basement drain smells like rotten eggs?

If your basement reeks of rotten eggs smell, then you are experiencing a sewer gas leakage somewhere. This smell is easily noticeable since it stinks badly.

Anyhow, sewer gas is hydrogen sulfide which comes from decaying organic matter from the sewage. This gas is entering your plumbing system somehow and that’s why your basement stinks of rotten eggs.

However, you don’t have to worry about your health since hydrogen sulfide is not harmful to humans. But, if you don’t do anything about the sewer gas leak in your basement, the gas will slowly start to create numerous problems inside our household.

That’s why dealing with this problem requires you to act quickly and get rid of the gas as soon as possible.

But, why is there a sewer gas inside your basement in the first place? Well, let’s see more about that.


Basement Drain Rotten Eggs Smell – Where does it come from?

Dealing with this kind of problem is always easier if you know where to start. In that light, you will first need to determine the cause and the source of the rotten eggs smell, and, after that, you can start with getting it out of your basement.

So, where does the rotten eggs smell come from? Well, the first thing a person would suspect is that it comes from draining pipes, and that’s correct. This type of smell comes directly from the sewer line that is connected to your basement with drain pipes.

This means that your plumbing system is not working properly and that sewer gas is finding a way inside your house.  Probably the most common source of rotten eggs smell in your basement is the dry trap.

Dry Trap

In case you didn’t know, the drain that is located inside your basement has a P-trap construction which blocks all the gases from the sewer entering the house. So, there is a portion of water inside the P-trap that just sits there and blocks all odors getting into your basement.

But, what happens when there isn’t any water inside the P-trap? That means that there is a free and unobstructed path between the sewer and your basement. And, because the sewer stinks badly, that smell of rotten eggs is directly entering your basement since there isn’t any water in the P-trap to stop it.

However, there are other sources of rotten eggs smell inside your basement. So, let’s take a closer look.


Clogged Drains

Something similar happens when your drain pipe in the basement is clogged. Namely, in order to have a perfectly healthy plumbing system, your drain pipes must be free of clogs or any build-ups. And, that is actually not an easy thing to maintain if your drains are used frequently.

But, the basement drain pipe is not used every day. So, there is a lot less chance that your basement drain gets clogged. However, it can happen and you will need to be prepared to unclog it as soon as possible.

As we all know, clogs and built-ups are usually consisted out of the ‘’not so easy to dissolve’’ materials. That’s why you will need something stronger to get rid of them.

If your basement drain pipe is clogged, the gas from the sewer will start to build-up right beneath the clog and it will start to smell bad. Even the clog won’t be able to stop the smell, it will only enhance it as the time pass by.

Gas Leakage

Now, if you are experiencing a gas leakage somewhere inside the sewer line that means that this problem is out of your hands. But, how can you tell? Well, you first need to inspect the first two causes of rotten eggs smell – the Dry P-trap and the Clogged Drains problem.

After you inspected the basement drain and determined that everything is fine down there, you should probably call a professional. It is quite likely that the sewer line beneath your home is leaking somewhere and that the gas finds a way inside your house.


This happens because of the poor installation of the sewer line pipes. So, the gas that leaks will find a way inside your basement through the cracks and you simply can’t do anything about it.

That’s why a professional is required to determine the problem and to fix it.

How to Get Rid of Basement Rotten Eggs Smell?

As we can see, there are three main reasons for sewer gas smell inside your basement. So, let’s see how you can get rid of this smell.

Solution 1 – Dry P-trap

In case your P-trap is dry, you just need to flush it with some water. This really isn’t such a hard thing to do since all you have to do is to pour some water inside the basement drain.

After that, the water will enter the P-trap and it will block the sewer gas from coming into your home.

Solution 2 – Clogged Drain

It gets a bit harder when you are experiencing a clogged basement drain. Namely, you will need to get rid of the clog and rinse the whole drain with hot water. So,

  • Unclog the drain - Take a ‘’plumbing snake’’ tool to unclog the basement drain. This tool will easily help you to get rid of the clog for good. Stick it inside the drain until you feel a bump. After that, start pulling and twisting the tool until you get it all out.
  • Rinse it with hot water – To make sure that everything will run smoothly down there, it is highly recommendable to rinse the drain with hot water after you unclog it.

Solution 3 – Gas Leakage

A gas leakage problem is definitely out of your reach. You will need to call a professional and let him deal with this kind of problem since you can’t do anything here.

Basement Drain Smells like Rotten Eggs

Conclusion: Basement Drain Smells like Rotten Eggs

Basement drain is a commonplace to notice a sewer gas smell since it is the lowest positioned drain inside a household, and therefore it is the closest one to the sewer. In that light, it is always a good thing to know what to do in case you experience stuff like this.

Anyhow, we have explained all the common causes of sewer gas smell that comes from your basement drain. And, now it is all up to you to get rid of it.