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Septic Tank Smell in the House? Here’s How to Get Rid of Septic Smells

As a rule, your septic tank should not be giving off odors. It is a sealed unit designed to lock both the waste and odors in the tank. So if you can smell septic tank odors in your house (rotten egg smell), it’s a warning. We will cover the septic tank smells if you should be concerned and what to do about them.

The first thing is to locate the source of the bad smell. Are they inside, outside, around a certain area in the yard, or is the smell everywhere? We will explore each of these, so you know what to do about these sewage smells and get rid of them.

What causes the sewer smell?

Septic tank smells are caused by sewer gases in the septic system that is escaping one way or another. The gases can include methane, hydrogen sulfide, and carbon dioxide, enough of these gases can be harmful or even life-ending (some cause explosions).

Over time these septic tank gases build up and are usually contained in your septic tank, but if you smell them in your house, there could be an issue that you need to identify.  


Click here to find a septic professional near you 


Septic tank odors outside of the house

If you’re experiencing septic tank smells outside, you will want to check around the tank itself. There are a few places where the sewage odor, or sewer gas odor, can be coming from.

Septic gas smells around the tank

Your septic tank may always have a weak smell, but that’s nothing to be worried about. But if the septic tank smells have gotten stronger then it’s time to inspect your smelly septic tank. Make sure the tank cover is securely fastened.

The septic tank could have a concrete lid, metal, or plastic lid. If you’re not sure where your septic tank is located around your house, check with the professional as it could be buried under a foot of soil. Have a newer tank? You will have a plastic lid, and the seal on it may be damaged.

You can look into replacing the maintenance hole cover or fixing the seal. Another thing to check for is if your septic tank is leaking.

Do a visual inspection of the grass around the area to see if it is wet or if the grass is greener. In this case, you will need to contact a septic system professional to repair the tank.

One last thing is that if you have a new septic tank, perhaps you just build a custom home, then you may be the victim of a bad installation. Contact your builder to see what needs to be done. This was our case, the septic tank had cracked, and they needed to excavate the tank and repair it.  


Leach field smells

A quick rundown of how a house with septic tanks and septic systems works. All of the water and waste that goes down your drains ends up in the tank.

If you have a drain field, the water that enters the tank eventually gets pushed through a pump (the pump is either in your septic tank or in the house) and pushes the greywater into the drain field, where the water is returned to the soil.

The soil cleans the water until it returns to the water supply. If you notice that the smell is coming from around your leach field (drain field), there could be a problem.

That area does not have septic smells. The likely culprit is an issue with the pipes in the drain field. Your leach field pipes are likely clogged, damaged, or crushed.  


Clogged drain field pipes

Your plumbing system can clog for a few reasons. Sometimes solid waste gets through and clogs the system (a way around this is to put a filter in your septic tank pump, it also blocks hair which is another thing that can cause a break in your septic tank pump).

This can cause a clog and back up the pipes. Another reason for the clog is that there could be tree roots growing into the pipes.

Tree roots are great for seeking out moisture, which isn’t great if you have trees around your field. If you have trees growing too close to your field, the roots may be in the pipes and clogging them up.  


Crushed leach field pipes

When your drain field pipes get crushed, the water is likely to get blocked before it can drain into the soil. This can happen when driving heavy machinery over the field. The pipes are under the soil but can get pushed up over time.

If you have done some larger landscaping and had bigger machinery on the field, it may have crushed the drain pipes. This may be the reason for the smell. In this case, you will need to contact a septic system professional to assess the situation and the next steps.  


Click here to find a septic professional near you  


How to fix leach field smells

If you notice the ground is wet around your drain field or that the sewage is rising to the surface, there is an issue with the field, and it needs to be repaired. This type of issue can cause damage to anyone around it and can be supplied as category 3 water damage and needs to be handled immediately.

It is a threat to you and your family as well as to the wildlife in the area (not to mention house pets). To fix this issue, you will need to contact a septic tank professional to see what can be done. In the meantime, you may need to get your septic tank pumped to try and reduce the amount of water going into your drain field. 

septic tank smell in the house

Sewage smells around the outside of the house

If you notice that there are sewage smells coming from around the outside of your home but can’t quite identify where they are coming from, it may be an issue with your plumbing venting pipe. If you are experiencing smells, it could be that the pipe isn’t long enough. You may notice these smells on days when there is little to no breeze.

This isn’t as urgent because the gases are being properly vented. However, no one wants to deal with sewage smells when they are outside. The easiest thing is to call a plumber to extend the vent pipe. Alternately, another solution would be to have a filter put on the top of the vents to cut down on the septic odors. These carbon filters can last up to 5 years and will need to be replaced.


Be sure you have a septic system and not a cesspool. Here are the difference between cesspool vs septic tank.


Septic smells inside the house

It’s most likely this is where you first noticed your sewage smell was in one of your drains.

A skunk smell inside the house is very noticeable. You may think it’s a toilet issue. 

But if you’ve cleaned the toilet and given a few strong toilet flushes and the sewer gas odor doesn’t go away, it’s likely there is a bigger issue than just the toilet.

Is the tank full?

If you begin to notice the rotten eggs smell from various drains around the house, it could be that it is time to get your septic tank pumped. As a rule, you should get your tank pumped every 3- 5 years. But depending on your living situation and the size of your tank, you may need to get your tank pumped more frequently.

We have ours pumped every year. Some things that may indicate your tank is full are a gurgling noise coming from your sink or a slow filling toilet; both can both be the cause of a full tank.  

septic tank smell

Septic tank smell in bathroom

Why Does My Bathroom Sink Smell? If you have noticed that the smell is just coming from one drain, it could be easy to fix the septic odor inside your house problem. Drains all have a P-trap; this is a U-shaped bend in the pipe and is where water sits until more water comes down the pipe, flushing the old water and replacing it with the new water.

This water also serves as a block for gases to pass through the plumbing system pipes and back up through the drain of the sink. If you don’t use the sink fairly often, the water in the P-trap can evaporate, and the gases from your tank can enter your home.

This is often the case when you have an unused sink like a guest sink or a utility sink in the basement. (This can also happen if you have been away from home on a trip for several weeks).

To fix this problem, run water down all of your drains and flush your toilets. This will put new water into your P-trap.

Next, turn on the fans, open some windows and run your HVAC to ventilate the air in the home. You can also incorporate this into your house cleaning schedule; when you are cleaning a room with a drain, make sure to run some water down it for a little bit to flush the tank.

Problems flushing? Use a toilet paper that is septic safe. Here are the best septic safe toilet papers.


Washing machine smells

If you notice it is your washing machine that is giving off the bad odors, then it could be that the p-trap wasn’t installed properly or it is clogged. Use the same method to try and flush out the sink line, and if that doesn’t work, use the adjustable drain hose of the washing machine to make sure it hasn’t extended too far into the drain box pipe.  

Septic smells in your basement

If you notice that there is a foul odor in your finished basement, it could be that the floor drain trap is stuck open or dried out. This will allow the tank to flow back into your house, and the gases can begin venting through shower stalls in the basement and other places. It could be clogged, or it may need to be replaced.  

Gaskets and seals

If you are finding that none of these is the issue, it could be that you have a broken rubber seal or a defective gasket. Over time these can dry out and need to be replaced. This is a common occurrence in older homes. If the smell is strongest from the base of your toilet bowl, it could be that you need to replace the wax seal on the toilet. To repair these, call a plumber to inspect for any seals that need to be replaced.  

Clogged plumbing vent stack

This is known as a vent stack or plumbing vent pipe. If you have a clogged vent pipe, then the gases have nowhere to escape and will come back into your house.

The plumbing vent pipes are the pipes that come out of your roof. They allow sewer gases to escape through these vent pipes. It also helps move the wastewater through the house and into the septic tank.

This can be one of a few things, but they are all related to your venting pipe. If your pipe is clogged, it will need to have the clog removed.

Unlike unclogging your sink, or unclogging your bathtub, removing the clog from the plumbing venting pipe requires you to go on the roof. If you do not have experience in this, it’s best to call a plumber. These types of clogs can happen when doing yard work.

They can also happen if there is a bird’s nest or if you have a lot of trees around the house and leaves and debris have fallen in.

Another thing that can block your vent stack is cold weather. Ice damming can occur if you have extremely cold weather, and this ice will prevent proper ventilation causing the gases to come back through the sink. 


Click here to find a septic professional near you  


Tank chemistry is causing smells

Lastly, another septic tank problem could be that the chemistry in your tank is off. The pH levels can get too acidic to digest, and it can result in the tank smell.

A higher amount of these gasses (methane, carbon dioxide, and hydrogen sulfide) can even lead to explosions. To try and get rid of these odors on your own, try pouring a cup of baking soda down the toilet bowl or drain once a week.

This can help balance out the pH levels of the tank and eliminate the smells. If you try this for a week or two and don’t have any luck, it’s then time to contact a septic service professional to help you with your tank odors.

It could be that it’s time to get the tank pumped and, in doing so, remedies the odors in the tank. Keeping the right pH level is pretty straightforward, but you can help by not putting things in the toilet that aren’t biodegradable. Things like cigarette butts, feminine hygiene products, and paper towels don’t break down and can cause damage to your septic system. 


Does the septic tank need to be replaced?

Septic tanks don’t last forever, if you do these and the odors persist you may need to get your septic tank replaced, see how long a septic tank lasts


Final Thoughts on eliminating septic odors from your house

While these smells can be terrible, they’re not the end of the world and are pretty easy to handle. Try the methods mentioned and if you are having issues, make sure to contact a professional in your area. Use the link below to find someone to help you.


Click here to find a septic professional near you  


Now check out Holding Tank vs Septic Tank: What you need to know

More smells to be aware of and what they mean

Vinegar Smell in House

Bad Smell Coming From One Vent in House

House Smell Like Skunk (and How to Fix It)

Burning Plastic Smell in the House

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