Home bathroom and sanitaryOutflow gurgles, stinks, water comes up - that helps!

Outflow gurgles, stinks, water comes up - that helps!

  • Checking the causes
  • Ventilation of the sewer
    • Function of the vent
    • Solution for missing ventilation
    • Mini solution - inexpensive and fast

There is hardly anything more unpleasant in the household than a drain that stinks or even sends sewage back. This is often related to water jamming at a more remote location in the piping system. Even more often, however, the venting of the sewage system is the cause of the problem. Here we show you how to get to the bottom of the problem and solve it.

Especially when a larger amount of water, such as toilet or bathtub is drained, many users observe the problem. Water from the tub comes up in the toilet or even worse, the toilet water suddenly spills in the tub. In the sewage system, it gurgles and the resulting rising air stinks extremely. So that you can clarify whether it is perhaps a simple blockage in the siphon or a problem with the venting, we have collected the causes and solutions once with the appropriate tips. Action tube free running!

You need this:

  • Spindle big and small
  • Wasserpumpenzange
  • soft cotton towels
  • bucket
  • mechanical pipe breather
  • possibly branch pipe
  • new siphon with ventilation sockets

Checking the causes

If there is already a strong smell of sewage treatment plant as the sewage gushes, there is usually something wrong with the venting of the system. Nevertheless, you should exclude all simpler causes beforehand. It can not do any harm anyway if the siphon is cleaned from time to time. At least the siphon can be a source of the unpleasant smell.

  1. Check siphon

First, you should check whether the siphon or odor trap can work, or whether there may be hair and dirt blocking or restricting the way. Before you work long-winded with baking soda or other pipe iniminators, you should reach for a gurgling runoff equal to the water pump pliers. For a sink or kitchen sink, you can easily open the siphon.

  • Put buckets under the drain
  • Release the screw connection of the siphon
  • Clean the siphon
  • possibly pierce the drain with a fine spindle for a while
  • Screw on the siphon again

Tip: Under a sink are today often very noble jewelry siphons, which are high-gloss chrome-plated. Be extremely wary of these specimens. To avoid scratching the surface with the water pump pliers, you should wrap soft old cloths around the jaws of the pliers.

  1. Check inspection openings

At the inspection openings of the sewer, you should check whether the wastewater can flow freely. Have another person operate the toilet flush and see if the water gets by in a rush. If it is just a trickle, there might be an obstacle in the pipe before the opening in question. Then you should try to open the tube with a long spindle backwards. If you actually encounter an obstacle, loosen it by repeatedly poking the spindle and then rinse thoroughly.

Tip: In the case of a vertical inspection opening, you should of course open the flap only a small gap at the top edge and illuminate it with a flashlight. Otherwise, you literally stand in the rain, but in no pleasant.

  1. Check ventilation on the roof
roof ventilation

If it gurgles and stinks, however, this is a clear sign in the direction of the vent, because it does not work, the sewer pipe sucks the odor trap because of insufficient counter air. Also, the rising of water from another sanitary object is an indication of this error. If the drainage of the sewer line does not work or ceases, it may be due to a design error in the design of the vent or in a closure. So first, see if there birds have built a nest at the vent plug, which makes it gurgles and stinks.

Ventilation of the sewer

The vent for a sewer pipe must be routed up each vertical pipe of the sewer. It should protrude through the roof to the outside and not, as often happens, already under the roofing end. A completely closed sewer can not work, but there are usually several odor traps available and the water then seeks an alternative way by sucking it empty.

Function of the vent

What happens in a vent, you can imagine, if you take a transparent hose to hand. Fill it with a little more than half with water. If you change the height at one end of the hose or fill it with energy, it starts to crackle. The vent ensures the vertical part that the air can escape. If it is missing or clogged, water and air will spill out at the other end. However, if water is filled only slowly in a trickle, no air bubbles are created.


So if a lot of water is poured in one go, the vent for the pressure equalization sucks the siphons in the whole house empty, the result is that it gurgles and stinks. Just wash your hands with a small trickle, usually nothing happens. That is also the reason why we often notice the problem first when flushing the toilet. In many cases, the problem occurs in an old building, because after a structural change, possibly a new pipe has not been connected to the vent. Do-it-yourselfers often build an additional guest bathroom without even knowing about this problem.

Solution for missing ventilation

Of course you can not just rebuild the whole house because of the ventilation. Especially if the house has been rebuilt several times and the attic has now become a living space, no one knows where the lines are exactly and on the other hand is a vent on the roof with so much effort and costs that many homeowners already rather accept that it gurgles and stinks. But today there is a much simpler solution anyway.

  1. Mechanical pipe aerator

The mechanical tube aerator works automatically when a vacuum is created. The small appliance opens and lets so much air into the sewer pipes that the siphons in the house are no longer empty. If the negative pressure is eliminated in this way, the Rohrbel├╝fter closes automatically again.

Tips: If the pipe aerator is to be installed in an adjoining room, such as a laundry room, which may not be frost-proof, then buy a special frost-proof appliance. However, many of these larger aerators are specifically isolated anyway. The prices range from a little under 20 euros to about 60 euros for special pipe aerators in the toilet area.

  1. Installation of a pipe aerator

You must first find the highest point of the sewer. There the aerator will be installed. Most manufacturers now even offer differently sized pipe aerators for the sewer line. These not only fit the different sizes of pipe, but also offer a different volume of air flow. While the large pipe aerator in most manufacturers introduces around 30 liters of air per second into the system, the small aerator creates at least eight liters of air per second.

  • large pipe aerator for pipes DN 70, DN 90 and DN 100
  • Small pipe aerator for pipes DN 40, DN 50 and the special size 11/2
Pipe aerators - different versions available

Install the pipe aerator on the toilet

  • Remove toilet bowl and separate from cistern
  • Pull drainpipe out of the ground or wall at the rear
  • Insert new drain pipe with additional plug / Y-pipe
  • Place a large pipe aerator on the second stopper and seal
  • Reinstall the toilet and screw it to the floor
  • make sure that the toilet is properly sealed to the pipe
  • Reconnect the cistern and also check the seal

Tip: When buying the pipe aerator, also pay attention to the rubber lip on the connector. This rubber lip ensures that odors no longer enter the rooms, and adapts to the different pipe sizes. When buying, you should also make sure that in the mechanical tube aerator insect screens were installed. Otherwise annoying insects will get into your toilet or bathtub.

Mini solution - inexpensive and fast

Not every household has countless meters of sewer pipe, and even if it gurgles and stinks, there are always gradations in the size of the problem. Even then, the manufacturers of sanitary accessories have developed resourceful solutions. A nice practical example is the pipe extension for the siphon, which immediately has a small vent installed. These are particularly easy to install and the costs are also very manageable.

  • Remove the siphon
  • replace vertical siphon pipe with new vented pipe
  • Check seals and rubbers
  • Reinstall the siphon

Depending on whether made of plastic or chrome-plated metal, these extensions fit optically well to the existing system. These pipe extensions are also available with a 90 degree angle in both versions. From about 20 euros you are in this mini solution. The second simple solution consists in a complete siphon system, in which also a pipe vent is integrated. These systems are available from about 50 euros both for the sink and for the washstand.

Whether this simple solution but really enough air into the system directs when the toilet is flushed, must give each of the practice test at your home. Success will certainly depend on how far away the toilet is from the relevant vent, but it should at least significantly reduce the problem.

Prices for the different solutions:

  • Pipe breather large, insulated, with insect protection, white - between 30 and 70 euros
  • Pipe breather large, uninsulated, without insect protection, gray - between 20 and 45 euros
  • Pipe vent small, uninsulated, with insect screen, white - between 25 and 40 euros
  • Pipe breather small, uninsulated, without insect protection, gray - between 10 and 30 euros

Tip: Remember that you also need a new branch pipe for the above variants. Although this does not cost much, it has to be both space and sealed. The effort is so much greater than with the simple solutions that are grown on the siphon.

  • Pipe extension siphon with integrated breather, plastic white - between 18 and 30 euros
  • Pipe extension Siphon with integrated breather, metal chromed - between 22 and 40 euros
  • Pipe extension siphon, integrated breather and 90 degree angle, plastic white - between 18 and 30 euros
  • Pipe extension siphon, integrated breather and 90 degree angle, metal chromed - between 25 and 45 euros
  • Siphon complete with breather - Sink with appliance connection - from about 45 Euro
  • Siphon complete with breather - sink - from about 40 euros

Tips for quick readers

  • Finding the problem for gurgling runoff
  • Clean the siphon at the sink or washbasin
  • Spindle sewage pipe
  • Check the inspection opening of the pipe
  • Check the ventilation of the sewer
  • Free and remove exhaust air nozzles from bird nests
  • add additional pipe branch to toilet / sink
  • install mechanical pipe aerator
  • Attach the integrated pipe aerator to the sink or washbasin
  • install new siphon complete with pipe aerator
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