Why Does My House Smells like Sewer When it Rains?

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We’ve all experienced a sewer smell coming from a drainpipe somewhere in our house.

However, in some cases, the sewer smell only appears when it rains. And, that indicates a whole new problem.

Anyhow, sewer smell is absolutely unbearable and it definitely needs to be taken care of. Also, there are plenty of reasons and causes of sewer smell inside a house.

But, it is easier to determine the cause when you know that this smell appears only when it rains.

So, let’s get down to it. Let’s see what is causing the smell and how can you get rid of it.

house smells like sewer when it rains

Why Does Your House Smell Like Sewer When It Rains?

In order to get rid of the stinky smell from your house, you will need to know what is causing it. Now, we know one thing, the fact that your house smells only when it rains.

So, as we all know, rain often results in a change in atmosphere which can affect your plumbing system.

Anyhow, the most common reasons why are you experiencing sewer smell when it rains are:

1 Saturation of the Rain

Every time it rains, the ground becomes soaked with water and that directly affects your drain field.

So, when the drain field is affected in this manner, there will be a lot of signs of septic problems. Anyhow, the real problem here is that you can’t deal with rain.

Also, if you are located somewhere where the rain falls more often, then this will definitely happen.

So, what exactly happens inside a septic tank, and how does that affect your plumbing system?


First of all, the septic tank is slowly but surely going to be filled with water from the rain. That will increase the liquid level inside the septic tank which is going to increase the back pressure.

Now, as we all know, the septic tank is full of different kind of gases.

These gases will be forced to go into your plumbing system under a lot of pressure (the back pressure created by the rain).

So, when these gases enter your plumbing system, they try to find the exit and leave the pipes. And the only way to go from there is inside your house.

That’s why you smell some really bad odors inside your house that come directly from the sewer.

However, sewer smell can’t come into your home if you have a perfectly running plumbing system. But, in most cases, the plumbing lines and pipes are not that durable and even a little loose ring can be enough for sewer smell to enter your house.

It all happens in this order:

  1. Rain falls 
  2. Ground gets soaked
  3. The liquid level inside a septic tank rises
  4. Back pressure is created
  5. Gases will enter your plumbing system
  6. Your drains, vents, and a waste system will smell like sewer gas
  7. Sewer smell will enter your house

As we can see, rain saturation is a serious problem that you can’t simply fix. There are some solutions to get rid of the smell, but you can’t prevent it.

2. Atmosphere Change

It is a known thing that air gets heavier when it rains. Now, since the air becomes heavy, that will directly affect the release of the gases into the atmosphere from the septic tank. Also, there won’t be a proper release of gases inside your vents.

So, what happens with these gases then? Where do they go when the air gets heavy?

The first thing to know about this problem is that heavy air will simply push these gases and won’t let them exit into the atmosphere properly. These gases will stay low to the ground due to the atmospheric pressure.

That will result in a sewer smell that will enter into your house through the vents and drains. And, the worst part about this is that you can’t prevent it.

house smells like sewer when raining

Even if your plumbing system is perfect and it works like a charm, there will still be sewer smell inside your house when it rains.

However, it doesn’t have to mean that the odor will be so strong. Sometimes, only a small portion of these sewer gases will enter through the vents and that won’t create a huge problem.

But, it is always the best not to have your house smell like sewer or rotten eggs at any time.

3. Stop the Smell

Now, there are a few things you can do to stop the smell from spreading more inside your house. Once you feel and smell the sewer gas inside your house that means that there is a leak somewhere.

So, you simply can’t find the leak that quickly, and, it is always a good thing to cover the whole plumbing system.

This means that you need to do a couple of things after the rain stops. Here they are:

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Run water through all drains 

After the rain stops and your house smells like sewer gas, you simply need to run water through all drains that you have in your house.

Namely, you should just let water through your shower drain, sink drain, toilet drain, and every other drain that you can find.

This will properly rinse the drain and balance the water level inside your P-traps. Also, sewer gases will have to exit through the main vent and your house will not reek of rotten eggs.

Check for clogs

In some cases, the gases will start to lower the water level inside your P-traps and clogs will be formed more easily. That’s why you need to check for clogs every once in a while.


Conclusion: House Smells like Sewer When it Rains

As we can see, rain can affect our plumbing system and that can result in some very unpleasant smell inside our house. In that light, we can only do a couple of things to stop the smell.

However, preventing this kind of problem is not possible. 

In some households with two or more bathrooms, the smell will be even worse. That’s why you need to act quickly when the rain stops and pour a lot of water inside your drains.