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6 Reasons Why It Might Smell Like Sewage Outside Your House 

Note: This post may contain affiliate links. This means that at no cost to you, we may receive a small commission for made purchases.

Have you ever been relaxing in your home when suddenly the unbearable stench of sewage floods your nose? It has happened to all of us at one time or another. Or consider to live in a climate controlled, self-storage facility by Will Stor LLC

While it isn’t usually a cause for concern, it can sometimes be because of something that may end up very harmful to your health.

There are a multitude of reasons why you may be able to smell sewage. Sewers are everywhere – we all have drains and toilets and all that water and waste has to go somewhere.

Because of this, it is very common to experience problems with your sewage gas and drainage systems.

In this article, we are going to cover six of the most common reasons that you may be able to smell sewage outside or inside your house. So, let’s get into it! 

Reason No.1: Sewer Pipe Leaks

Perhaps one of the most common causes why it smells like sewage outside of your house (see also ‘The Reason Your House Smells Like Sewer When It Rains‘) is sewer or septic pipe leaks.

This is when sewer gas leaks out from damaged pipes. Some causes of damaged pipes are corrosion and rust, a blockage, or holes along the pipe or joints. 

When items are flushed down the toilet or drain that shouldn’t be, a blockage may occur.

Flushing items such as cotton pads, baby wipes, and sanitary products can cause blockages and drainage problems and that is why you should never flush products like those down the toilet. 

Sewer and septic pipe leaks can be solved relatively quickly by a plumber.

Usually, they will use a plumbing camera to find the precise location of the cause of the leak.

Another way that they may try to identify the problem area is by using dye or steam so that the leak appears above the ground.

Once the problem has been identified and located, your plumber should suggest a solution such as the replacement of the sewer line or hydro jetting the pipe.

Reason No.2: Drain Traps

Drain taps are in place to prevent sewer gas from entering your home. The drain traps should always be airtight to ensure that any leaking is prevented. Sometimes these taps can become dry or clogged.

When this happens, sewer gas can pass into your home due to faulty taps. There are a few factors that can make this issue worse. These factors include the air outside – specifically when it is cold.

When it is cold outside it can cause issues in your drain traps. Additionally, issues can occur when the vents in a building’s indoor air pressure diminish.  

Before calling any plumbers or professionals, there is an easy and quick solution to this issue. You try pouring a quart of water down every drain that you have.

If however, this doesn’t help to improve the situation then it is probably time to call someone professional!

Reason No.3: Toilet Sewer Gas Leaks

Sometimes the seal on your toilet may become loose over time. Not only this, but sometimes the rubber linings can wear away as well.

This is a normal thing that can happen to toilets over time, simply due to being used. The seal can slip when the anchor bolts are not attached properly, or the wax ring is old and needs replacing (see also ‘How To Replace A Toilet Wax Ring Fast‘).

This can happen to any toilet and isn’t necessarily preventable as it’s due to age and wear.

You should contact your plumber if you believe there is a gas leak due to your toilet. You should ask them to check over every area of the appliance so that they can locate the route of the issue. 

Your plumber should also check the supply tubes and the mounting nuts on your toilet.

Any part that has been damaged or worn away will need to be replaced so that the gas cannot enter any longer. Sometimes your plumber may even find a crack in your toilet.

If this happens you will most likely need to have it replaced entirely to solve the problem.

Reason No.4: Roof Vent Pipes

Roof vents are quite similar to a drain tap, in that they are in place to prevent sewer gas from entering or leaving your home and going elsewhere into the environment.

Roof vents, however, allow the sewer gas to leave through the roof. Essentially, they help with the pressure of the plumbing system in your house and are very important.

6 Reasons Why It Might Smell Like Sewage Outside Your House 

Roof vents can fail when your drain traps are clogged or blocked. If your home isn’t properly vented then it can also cause very unsafe and harmful conditions.

For this reason, you should always check and ensure that they are kept free of any loose foliage such as leaves, animal nests, and lice or insects.

Additionally, more reasons can cause the failure of the roof vents. One of these is corrosion and rust where the vent may have worn away or been damaged.

Loose-fitting vents are another reason as well as there not being enough vents in total for the house. The last reason is if there are not enough vents for the building.

To prevent any damaged roof vents you should always check them and make sure that they are kept clear. This will help to avoid any problems occurring from there.

If you do locate an issue that you cannot solve yourself, you should contact your plumber.

They will be able to go through the pipes thoroughly and professionally, as well as clean every part of the vent by disconnecting and reconnecting the pipes. 

Reason No.5: Partial Septic Blockage

Blocked drains are one of the main reasons why sewage smells can occur. If the pipes are clogged or blocked then it can cause odor not only outside but inside as well.

These smells will be more prominent while using water inside your house, such as showering or bathing or even simply running the taps.

You might also be able to smell it if there are harsh winds outside that force the gas towards areas it wouldn’t usually be.

If you want to avoid this issue from happening then it is very important not to flush items down the toilet that shouldn’t be flushed.

The only items that should be flushed down the toilet are human waste and toilet paper.

Anything like baby wipes, sanitary products, cotton pads, cat litter, and other objects can easily cause partial and even full blockages.

Reason No.6: Frozen Septic Fields

Septic tanks (see also ‘Cesspool Vs Septic Tank‘) can freeze over time, especially if the system hasn’t been used for a very long period.

Ice can end up clogging the entire septic system meaning that it will back up completely. This is an issue that generally happens during wintertime.

One way that you can prevent this from happening during the colder seasons is by placing mulch and foliage over the septic system to insulate it.

If you notice that your system has frozen, you should call a professional. They will be able to locate where exactly the ice blockage is.

Sometimes, the plumber may not be able to solve the issue straight away. Instead, you will have to wait till the weather warms and the ice thaws.

Dangers of Sewer Gas

Sewer gases can become very harmful to your health if left unchecked. Not only this, but it can affect your home and plumbing system as well.

If you ever smell any unusual odors or see sewage you need to contact a plumber straight away so that they can solve the problem as fast as possible. 

You can purchase a gas detector that will raise an alarm if the gas levels reach too high and pose a threat.

If you ever find yourself in that situation then you should leave the premises immediately and contact the local fire department.

It is especially important not to turn on and use any appliances or even light a match. Even a very small flame can cause a fire.

Final Thoughts

If you suspect any problem with your sewage system you should contact a plumber immediately. The situation must be dealt with as fast as possible to avoid any unwanted problems that could occur if left alone.

Although smelling sewer gas isn’t usually a cause for concern, it is better to be safe than sorry and try and get the issue located and sorted straight away.

If issues are left untouched and unsolved then they may become worse over time.

This can then cause a greater risk to you and your family further down the line.

So, to recap, if you suspect anything is wrong with your sewer and drainage system or can smell sewer odor, it is the best idea to contact a professional to come and survey the area and diagnose any problems that may exist.

author avatar
Anthony Barnes
Anthony Barnes is the founder of Water Heater Hub and a second-generation plumber by profession. Before developing Water Heater Hub, Anthony Barnes was a full-time plumber, and he has undertaken a wide variety of projects over the decades. As a second-generation plumber, it was easy for Anthony to get used to the technicalities of all from a tender age


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