The smell of sewage in the toilet: an overview of the possible causes and solutions

Nikolay Fedorenko
Checked by a specialist: Nikolay Fedorenko
Author: Tatyana Sokolova
Last update: March 2020

The unpleasant smell of sewage in the toilet quickly spreads outside the bathroom, creating discomfort for the residents of the apartment or house. Modern air fresheners and room ventilation are not able to solve this problem.

The appearance of an unpleasant aroma is the result of any malfunctions. Therefore, in order to get rid of the smell, it is necessary to determine the cause of its occurrence and take urgent measures to eliminate it.

You will learn all about ways to search for the causes of negative odors and methods of dealing with them by reading the material presented. We examined and systematized in detail both the prerequisites for their appearance, and methods of elimination. The information is supplemented by visual photo and video applications.

What to do when an unpleasant odor appears?

A bathroom is a sanitary-hygienic premise necessary in each apartment, which requires special care. If tenants comply with sanitary requirements, the toilet should not have any odors, including the smell of sewer gases.

In order to eliminate the unpleasant scent of the sewer, spreading to other rooms, you should first identify the cause of its appearance.

With gases from the sewage system, not only pathogenic organisms can penetrate into the room, but also various harmful substances - hydrogen sulfide, sulfur oxide, ammonia, mercaptan and others.

Inhalation of these gases is harmful to humans and may be harmful to human health. Therefore, if there is a sewer smell, you must immediately identify the source of its appearance and eliminate the problem.

The first thing that owners of a room who usually have no idea about the features of the sewer system usually do is use air fresheners.

Sewerage Scheme
The scheme of sewage in the toilet will allow the owners of the living room to get an idea about the design and principle of operation of the sanitary equipment

Modern aerosols have a variety of flavors that can temporarily interrupt the unpleasant smell of sewers, but they are not able to eliminate it.

Possible causes of the appearance of a smell are the flow of gases from a drain hole of a certain or several plumbing fixtures.

Quite often, a disgusting "aroma" appears in the bathroom due to clogged devices or improper installation of plumbing equipment. However, there are other possible odors.

Problems with the operation of the water seal

Most often, the smell of sewage appears in the bathroom if, for whatever reason, the water seal stops functioning normally.

In siphons installed under the plumbing equipment, there is a water plug, which acts as a barrier to the path of gases coming from sewer pipes. If there is no cork for any reason, then the gases penetrate the toilet unhindered, spreading an unpleasant odor.

Siphon blockage
The reason for the siphon to work improperly is that the section of the sewer pipes is completely filled with drains. Because of this, the water plug is removed from the water seal, it becomes empty

The siphon is located under the basic sanitary equipment of each toilet - the toilet. It is made in the form of a curved pipe in which a certain amount of water accumulates. The hydrolock acts as an effective barrier to unpleasant sewer odors.

Siphon mounting
The correct installation of a siphon (water trap) in the room of your bathroom will prevent the possible appearance of sharp odors from sewer pipes and plumbing equipment

In the event that significant violations occur in the operation of the siphon, a constant sewer smell will be observed in the apartment. Consider the main reasons why the siphon ceases to perform barrier functions.

Problem # 1 - Incorrect siphon installation

Mistakes made when installing a water trap provoke the appearance of a bad smell of sewer gases.

Suppose that during the installation of a bottle type siphon, the outlet pipe of the pipe was set too high. In this case, the gases from the sewer will pass on top of the water plug, due to which the siphon will not be able to fully function.

Toilet siphon
When installing the siphon, it must be taken into account that an excessively low location of the outlet pipe will lead to a decrease in the level of the water plug

To fix the problem, the outlet pipe must be moved - it should be located 2-3 centimeters below the water level.

Problem # 2 - Water Cork Drying

If any plumbing equipment has not been used for a long time, the water plug may dry out. As a result, sewer gases will freely enter the toilet.

In this case, troubleshooting will not take much time and effort. Water must be secured so that the breech block is completely filled.

The smell of sewage in the toilet due to lack of water plug
Drying of the water plug is a frequent occurrence in bathrooms that are not used for their intended purpose. You can fix the problem yourself, without contacting a specialist

If you plan to leave the house for a long time, it is recommended to pour a little vegetable oil into the drain. The film will reduce the rate of water evaporation and increase the time period, due to which the water plug will not dry out quickly.

Problem # 3 - Stretching Corrugated Pipe

When using plastic siphons with a corrugated pipe, a bad smell can occur due to the fact that the corrugation has sagged over time. This often happens when not special clamps are used to fix the knee, but an electrical tape or ordinary adhesive tape.

Corrugated pipe
When choosing a corrugated pipe for installation in your bathroom, you need to take into account that it has the properties of stretching over time. This may cause system problems.

To eliminate this problem, it is necessary to give the corrugation the correct position and fix it with a clamp.

Problem # 4 - incorrect installation of the corrugation

An unpleasant sewer odor in the toilet may indicate that installation rules have been violated corrugated water seal. It's about bending to form a siphon.

If the installation of plumbing is carried out by an inexperienced specialist, he may not know that the corrugated pipe should be bent with a knee, and then fix it in this position. Sometimes the bending of the corrugation is made insufficient.

Installation work
Incorrect connection of the corrugated plastic pipe to the exhaust pipe of the plumbing device - toilet. Incorrect installation may cause malfunctions.

To correct the installation error, it is necessary to bend the corrugated pipe to the desired configuration. After that, it is necessary to fix the corrugation with a special clamp made of plastic. For the installation to be successful, it is recommended to use the services of a specialist.

Problem # 5 - siphon clogging

An unpleasant odor of sewer gases in your toilet may be caused by normal clogging. plumbing siphon. The sewage settles in the siphon knee and begins to decompose, releasing a fetid odor.

In case of clogging of the water seal, it must be washed. You can use chemicals for washing, which are sold in household chemical stores. In some cases, mechanical cleaning of the hydraulic seal is necessary.

Bottle siphon for sink
Bottle type siphons can be easily cleaned without dismantling the equipment. To clean the water seal, unscrew the bottom element of the bulb. However, these toilet appliances are not suitable.

More often corrugated siphons get clogged in practice. This is because they have a folded surface on the inside of the plastic pipe. This feature of the corrugation design contributes to the retention of garbage, grease, waste and other effluents. In order to rinse the corrugated siphon, it must be completely dismantled.

Stable operation of siphons, through which plumbing is connected to the sewer, will be ensured by the installation of a vacuum valve:

Other types of problems

If there are no problems with the water seal, then you will have to carefully examine the room, paying attention not only to the sewer system, but also ventilation and other nuances. We will try to understand in more detail what exactly can cause stench.

Reason # 1 - clogged sewer pipes

To successfully eliminate the clogging of pipes installed in the bathroom of an apartment or house, it is enough to purchase a special chlorine-containing agent.

For effective cleaning of sewer pipes in the bathroom and the bathroom, preparations from leading manufacturers are often used: Domestos, Deboucher, Tiret or Krot.

Cleaning the toilet
Cleaning the toilet with household products containing chlorine can be done with your own hands. The drugs are used according to the instructions on the bottle.

The drug is poured into the sewer for a certain period of time. Due to the effective action of modern household appliances, the blockage usually disappears, and the normal functioning of the plumbing device is established. If the household chemical product does not clean the pipe, then it is necessary to call the plumbing.

Reason # 2 - installation errors of the sewage system

Not only problems with the siphon can be the cause of the defective work of the sanitary equipment. The cause of the narrowing of the lumen in the pipe may be a clogged sewer. Methods sewer pipe cleaning detailed in our recommended article.

In this case, pipe cleaning is required. Errors that were made during the installation of the sewer system lead to breakdowns and drying out of the water plug.

Toilet installation
Installation of plumbing equipment in the bathroom of an apartment or house should be carried out taking into account accepted standards and installation rules

In some cases, when installing plumbing equipment, pipes of small diameter that do not comply with construction standards are used.

For normal operation of the sewer system, it is necessary that the cross-section of the pipe is not completely blocked by drains, otherwise a discharge will occur in the pipeline, which will lead to the failure of the installed water seal.

Sewer pipes
If pipes are laid in a cold room, icing is possible in winter. To solve the problem, it is necessary to melt the ice with hot water and pick up pipes of larger diameter

A clogged fan pipe is a common cause of plumbing malfunction. This element is displayed on the roof of the building and is designed to equalize the pressure in the installed sewage system.

The fan pipe may become clogged (for example, it is blocked by an ice plug in winter), as a result of which a discharge occurs in the sewer system.

Each time you drain the water (for example, when operating the toilet flush tank), the siphons break and the gases penetrate into the room. To eliminate the cause of the smell, clean the pipe.

Reason # 3 - system leakage

Reason for the appearance toanalytical smell may be a leak in the pipe or connections. It should be noted that it is not always possible to quickly locate a leak.

Sometimes a hidden installation of pipes is performed in the bathroom, which complicates the process of finding a problem. Drains flow slowly from the leak and lead to mold growth and an unpleasant odor.

Leak detection
To identify problems in the plumbing, you need to check the places of leaks in the sewer.In the case of flush mounting, it is difficult to immediately notice a leak

Plumbing equipment leaks may be in the most unexpected places. For example, it is quite difficult to detect leaks in the slab. The most common cause of leakage and the appearance of a sharp sewer smell in the toilet is a loose connection of the corrugation and the drain pipe.

Having found this defect, it is urgent to replace the corrugation, as well as restore the mandatory tightness of the pipe joint. If leaks in the connection between the sewer pipe and the siphon are found, sealant must be used.

The silicone layer will reliably protect the joint area of ​​the elements of sanitary equipment from leaks.

Reason # 4 - poor ventilation performance

In the toilet and in the bathroom, water is used daily, so in these rooms there is an increased humidity. To successfully combat this phenomenon in the bathroom and other of the above premises, it is mandatory ventilation system.

Most apartment buildings use a natural exhaust system, but it does not work effectively in every case.

Fan cleaning
Keep in mind that the ventilation ducts are always clogged with cobwebs, dust and other debris. For this reason, they should be cleaned periodically.

In order to check how well the installed ventilation system works, a simple test should be performed. It is necessary to take a sheet of paper and bring it to the ventilation. If it works efficiently, then the sheet is pressed against the grate.

If the paper sheet falls onto the floor, the ventilation system does not work properly and needs to be cleaned.

Check ventilation
Checking the ventilation system can be carried out independently by the owners of the room. To do this, use a sheet of paper or a lighter (match)

In some cases, cleaning the ventilation ducts does not bring the desired result, then there is a need for the construction of forced ventilation.

Additional equipment is usually installed in the hole for natural ventilation. The second fan is turned on as necessary - when using the bathroom.

To avoid ventilation problems, clean the ventilation holes as often as possible. For better air exchange, it is better to install a hood equipped with a check valve.

Reason # 5 - Incorrect pipe installation

It happens that a sharp sewer smell appeared in the toilet or in the bathroom almost immediately after moving into a new apartment or house. In this case, the cause of the stench must be sought in an illiterate sewage system.

Today, there are specific norms for laying sewer pipes that must be observed during installation. If there is a breakdown in the sewer, you will have to reinstall the pipeline, which will entail considerable expenses.

Toilet installation
Often an unpleasant odor in the bathroom appears due to improper connection of sewer pipes. If you violate the accepted installation standards, the system will not be able to work properly

Incorrect stench and stench arrangement of sewer pipesor rather, non-compliance with the optimal angle of inclination.

You can fix the error only by dismantling the system and installing sewer pipes under the right slope. You will learn from what angle it is laid to lay sewer pipelines from the article we have proposed.

If plastic elements are used, it is necessary to repair pipe joints that are loose. It is enough to install sealing cuffs or change gaskets.

Now, home owners prefer to build their own buildings. In this case, in order to avoid misunderstandings, it is better to entrust specialists with the development of a project of engineering networks and the installation of a sewer system and plumbing equipment.

Reason # 6 - non-compliance with hygiene rules

The owner of any dwelling should understand that one of the most common causes of unpleasant odors in the bathroom is non-compliance with hygiene rules.

The reason for the stench may be untimely washing off of waste products and a rare washing of plumbing equipment.

Wash the toilet
Each owner of an apartment or house must follow the usual rules of hygiene and constantly wash the sink, bath and toilet bowl with household appliances intended for this purpose.

To care for the plumbing in the toilet, it is enough to follow simple sanitary requirements and regularly wash the toilet with special means. They effectively kill microbes, saving the bathroom from the causes of a bad smell.

In the modern market of household products, disinfectants have proven their worth: Domestos, Toilet duckling, Dosia, Oda, Cillit Bang, Comet.

Toilet odor control products

Before ascertaining the causes of the sewer smell in the bathroom and eliminating the breakdown, it is recommended to use special household facilitiesthat temporarily eliminate an unpleasant odor:

  • Fresh air automatic odor dispenser or aerosol.
  • Stickers stripes or blocks that are attached to the toilet.
  • Flavored tablets for toilet flush tank.

For a country house and cottage, special care products are used country toilets and behind the cesspools.

The preparations contain bacteria that help to quickly process the entire contents of the toilet, eliminating the unpleasant odor of the sewer. More commonly used brands: Saneks, Bioforce septic, Septic Shock.

No. 1 - microspray and aroma dispenser

Both tools are attached to the bathroom wall. Their difference is that microspray gives out aroma after clicking on it, and aroma dispenser allocates it automatically during the day. In this case, the aroma is served after a certain period of time and in a metered amount. Among the popular brands - Glade, Airwick.

Automatic dispenser
Automatic aroma dispenser is a universal remedy that can eliminate unpleasant odors of any origin, but only for a while

Alternative option - helium freshener. It can be attached to the wall of the bathroom or put on a shelf. It deodorizes the room with pleasant aromas for 60 days.

All of the above funds superficially and temporarily solve the problem of unpleasant sewer odor in the toilet, but they are not able to kill germs, remove pollution and eliminate the cause of stench.

No. 2 - flavored tablets for a tank

An effective tool to get rid of the sewer smell is flavored tablets. They sink into the toilet flush tank.

After each descent, the tablet refreshes the bathroom with a pleasant aroma, effectively disinfects it and prevents the appearance of urinary stone and rust on the walls of the toilet.

Flavored Pills
The advantages of flavored tablets over alternative means are the possibility of reusable use, performing several functions at the same time and an affordable price

Flavored tablets used in the toilet flush tank are able to stain water in green or blue.

In the modern market of household chemicals, high-quality brand products are especially popular: Fresh, Rio, Snowter, Bloo, Liaara.

No. 3 - strip stickers and blocks

To eliminate odors in the toilet often use blocks and sticker strips, glued to the toilet. They deodorize the air and have antiseptic properties, helping to fight harmful bacteria. In contact with water, they provide pleasant freshness in the room.

Toilet sticker
The most demanded sticker strips Domestos and dressing duckling. They are designed for long-term action - approximately 450 contacts with water

Suspending gel blocks are effective against odors. They perform several functions at once: deodorize the air, wash and disinfect the toilet. Blocks are easy to replenish and are designed for 100 flushes. Most Popular: Domestos, Bref, Dressing duckling.

Conclusions and useful video on the topic

Some useful tips on how to get rid of an unpleasant toilet “aroma”.

It must be understood that if the unpleasant smell of sewage appeared in the bathroom once, it will appear again soon. Therefore, this problem should not be left to chance, but it must be solved. Timely repair of damage will save your time and money.

Do you have a special method of dealing with the negative “scents” spread by the sewer system? Do you want to talk about an effective method or do not agree with the information provided? Please write comments in the box below.

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Visitors Comments
  1. Valera

    At our place, the bathroom and the toilet are separate (in different rooms). Our problem is that the feces from the toilet, when flushed, go to the bathroom and sometimes go outside so that they are even able to push the cork in the bathroom. What to do in such a situation? Just before the rain (I don’t know what the weather is outside), we often have a stink in the bathroom. What could it be from?

    • Villages

      Valera, in the bathrooms, the toilet should be the last, after the bath and washbasin. From the bathtub and washbasin comes a sewer pipe with a diameter of 50 mm, and after the toilet, -100 mm. Apparently, your bath is located after the toilet.

    • Vladimir

      We had such a problem when the workers changed something on the roof, dropped a brick into the riser and it just stood at the exit.

  2. Valera

    Unfortunately, the fact that feces when flushed, we go to the bathroom, this is true, not my fiction.The text is literate and useful, I was hoping to get the same answer, what should I do. And the fact that you don’t have such a thing in your house was very lucky for you, and we have been tormented for many years now, we called for pipes to be changed on our heads. Thank you for your attention, you don’t need to answer, I already realized that no one will help us solve our problem, I’m not going to argue, it’s not interesting for me. I just wanted to say that there are such nightmares.

    • Boris Smirnov

      Thanks for the truth! We are with you!

    • Nikolay

      Hello Valera! The fact that you have such a problem indicates the complete incompetence of those who changed your pipes. Yes, and you are good too! Saved! Now you need to redo everything. Otherwise, the problem cannot be solved. Only this time call the plumbers. You will be without odors, and with a guarantee.

    • Expert
      Nikolay Fedorenko

      Valera, hello, I have 2 options:

      1. You do not have a common sewer system, but an autonomous septic tank. Suppose you have 2 drain pipes that are not combined. Sewer pipe goes above the pipe from the bathroom. The septic tank is filled to the last and now under water pressure, when the toilet is flushed, the water is pushed into the drain pipe of the bathroom.

      2. Incorrectly designed drainage system of the general sewer system. Which confirms your statement about replacing pipes. The way out is to urgently call a qualified specialist and make a call / replace the system, yet you breathe, in fact, poison.

  3. Elena

    The Smelloff tool (on the SmellOff label) helped me. The smell destroys instantly. Easy to use, important, which is absolutely safe for health, does not harm pets.

  4. Also faced with this problem when we moved to a new apartment. A terribly uncomfortable and unpleasant situation that caused discomfort and significantly annoyed. They tried all the fresheners, nothing helped to get rid of this smell. We changed the plumbing, cleaned the pipes and everything seemed to be normal. Even better if the bathroom has good ventilation.

  5. Sanya

    Of course, mankind has come up with a lot of sprays and disinfectants, but if there is a smell from the sewer into the house, you need to look for the reason. No aerosol can save. Maybe the pipe is leaky or the corrugation has gone somewhere. You need to carefully inspect everything and then repair it. You need to start with the toilet, the corrugation usually sags, inspect all siphons and be sure to check the ventilation.

    • Expert
      Nikolay Fedorenko

      Hello. The cause of the smell from the sewer, in the case of the correct design of the pipes, is also the discharge of the water gates. In the usual state, unpleasant “aromas” are cut off by the water that remains in the siphon, but if there is a significant drainage of water, sometimes these gates are pushed. The problem is solved by installing an air sewer valve that stabilizes the system pressure.

  6. Good afternoon. An unpleasant odor appears and then disappears especially in the morning in the toilet sometimes in the bathroom. The plumbing is changed, nothing was done. Siphons checked, no leaks. But the smell is terrible, we live on the 9th floor.

    The fan pipe has already been lengthened to the maximum on the technical floor. Specialists cleared the ventilation from the roof. We can’t understand what is the reason. The smell is not constant in the morning early or in the evening. Harsh and unpleasant. What is the problem? Tell me where to go?

    • Expert
      Nikolay Fedorenko

      A similar problem is observed only in your apartment or all on the floor? Neighbors above or below did not complain of an unpleasant smell? This will provide an opportunity to understand the size of the problem: local or global. Since you write that the smell appears only early in the morning or in the evening, this leads to certain conclusions! Smells appear only during periods of maximum congestion in the sewer system (in the morning everyone is at work, in the evening everyone is back at home).

      Most likely, there are common problems in the ventilation system, which can not cope during the period of maximum load. Or there is a blockage that makes itself felt in the mornings and evenings. In any case, you need to leave a written application for your Criminal Code, if the problems are not only yours, then do it collectively, so that the issue is resolved faster.

    • Valentine

      Hello, Yana, I had a similar case when replacing the toilet: it began to terribly “stink” of the sewer. The reason was simple, although it was not easy to find: the “respected” Chinese manufacturers of expensive plumbing added one small hole from the outlet of the toilet to the cavity under the drain tank.

      Such a reason would not even occur to a normal plumber. But I'm not a plumber, I found her, stuck it with silicone sealant - and everything went. And this is not a one-time defect. I checked in the store: all toilets are more expensive than 15000 r. with such a defect.

  7. Valentine

    I had to remove the toilet and a full inspection to look for everything unusual and wrong in his device. And when I found 3 obscure holes - I stuck a wire there. I didn’t go into 2 holes, but through the third I got out under the tank. Delov for half an hour. But I am all myself. And if you call plumbing - I don’t even know.