Connecting the toilet to the sewer system can be done in several ways, and each of them uses a connecting fitting of one kind or another — regular or improvised. The methods used have their pros and cons, but the general requirement for them is the reliability of the result. Accordingly, the quality factor of the connection of the device depends on the characteristics of the installed fittings and the quality of its installation.

One of the methods — connection using a corrugated cuff is used relatively recently and, due to a number of advantages, is widely used. Such a corrugation for a toilet bowl is simple in design, but has a number of design and operational features.

Since ignoring any nuances associated with the sewerage system is fraught with leakage of by no means clean water, we will take a closer look at everything you need to know about the correct use of this type of connecting fitting.

What is a toilet corrugation and why is it needed


An important advantage of corrugated pipes over smooth-walled ones is the ability to give them the desired configuration without collapsing the walls. This potential is highly demanded in a variety of situations, so flexible connecting elements of this design are produced in different lengths and diameters.

A type of corrugated pipe is also a toilet corrugation — a non-pressure fitting, through which the toilet drain pipe is connected to the sewer inlet. The product is a sleeve made of thermoplastic (sometimes with an internal hardening coating), the middle part of which has an «accordion» section. One end of the fitting is designed to be inserted into the neck of the sewer pipe, the other is put on the toilet drain.

The design is simple, but in some cases irreplaceable. For example, the toilet bowl was connected to the sewerage system with a rigid knee and was dismantled before the bathroom was repaired. If the level of the repaired floor has changed, but the sewer pipes have remained the same, it will no longer be possible to connect the device in the same way. In such a situation, it is easiest to use a corrugated drain to connect the toilet to the sewer.

You can’t do without corrugations even when the plumbing fixture needs to be moved horizontally relative to the sewer pipe. A flexible fitting is also convenient for arranging a temporary toilet bowl for the period of toilet repair.

Types and dimensions of corrugated pipe

Corrugations for toilet bowls are universal products, but are produced with differences in some parameters. These fittings are produced soft — with a middle part made only of polymer, and rigid — with walls spirally reinforced with steel wire around the perimeter.

Corrugations of the first type are easier to install, but less durable. In a stretched position, such a pipe can sag over time with crushing of the ribs, especially if hot water is poured into the toilet. Reinforced fittings are stronger and more durable. Since the rigidity of the middle part makes it difficult to install the product, both end nodes of such products have a swivel design.


When connecting a toilet with an oblique drain to the sewer, reinforced corrugation is often the only reliable option.

For ease of use, corrugated fittings are produced in different lengths. According to this parameter, the corrugations for the toilet bowl can be conditionally divided into 2 sizes: short and long. The length of short ones in a compressed state is approximately 20 cm, in a stretched state — 30 cm or a little more. For long corrugations, these dimensions are about 30 and 50-90 cm, respectively. When choosing a product by length, they are guided by the distance from the toilet drain to the junction with the sewer.

Corrugated lintels are also produced with a different cuff layout that is put on the toilet drain — it can be not only on the axis of the corrugation, but also at an angle of 45 or 90 degrees. To her. This adds options for the location of the device when it needs to be installed with an offset relative to the sewer pipe.

There are flexible connectors and fixed characteristics, tied to the standards for toilets and pipes. The inner diameter of the middle part of the corrugation is 110 mm. For connection to the sewerage, the fitting has on one side a rigid branch pipe of circular cross section with an inner diameter of 80-85 mm, on which there are several elastic sealing rings on the outside along the perimeter — for tightness of adjoining to the walls of the receiving neck.


At the other end, the corrugation has a plastic cuff with an outer diameter of 134 mm and a rubber seal of a conical section from the inside. The smaller internal size of the cuff is 75 mm and is designed to fit snugly over the toilet drain.

How to choose the right one and what to look for

Let’s make a reservation right away — when buying a toilet corrugation, you should not save. Models differ in wall thickness, plastic density, rubber seal quality and fitting surface smoothness. And how reliable the connection of the toilet bowl with the sewer pipe will be in your toilet depends on each of these parameters.

How to choose the right corrugation for the toilet? First of all, you need to choose a corrugation of the correct length. To do this, measure the distance from the toilet to the receiving neck. The ideal choice would be a fitting that, after installation, will be stretched to 20-50% of the minimum length.

The corrugation for the toilet bowl has a good margin of flexibility, but the bends of its middle part in the working position must still be smooth — otherwise the ribs-folds will be under load at the pipe turns, and over time the product will break in this place. An elbow collar fitting or an eccentric adapter may be required to meet this requirement.

When choosing a corrugation from several possible options, preference should be given to a product with thicker walls. In addition, the fitting must not have surface defects and folds on the seals.

Corrugated adapters of domestic production and even cheaper Chinese models are inferior in quality to products from foreign manufacturers. Their most common drawback is the poor fit of the pipe to the inner surface of the sewer inlet. To eliminate this, the connection point has to be additionally sealed from the outside.


Hence the conclusion — for responsible places it is better to purchase imported drain fittings (Equation — France, McAlpine — Scotland, Jimten — Spain, AlcaPlast — Czech Republic).

Advantages and disadvantages of toilet corrugations

Modern corrugated fittings are made from high-quality polypropylene, and this material has some advantages over cast iron. In addition, such products have some «advantages» due to their design.

Advantages of corrugation for toilet bowls:

As a result, there are many options for the location of the sanitary device relative to the place of connection to the sewer.

  • Ease of installation and the ability to install on your own — both instead of a rigid elbow, and when replacing a damaged flexible adapter.
  • Low price even products of famous brands.

Flexible adapters also have disadvantages:

  • Low strength characteristics — this «minus» causes a number of limitations. The pipe must be mounted only in an open way, it is impossible to close it into the base under the mortar. The walls of the corrugation are easily damaged by a sharp object or an open flame. Over time, the sleeve can sag under load, crumple at the bend, lose shape when draining hot water into the toilet. Polypropylene is often damaged by rodents.

When do you need to replace the corrugation

The service life of corrugated adapters, when properly installed, is measured in years, and the durability of products from well-known manufacturers is naturally higher. However, over time, high-quality corrugations need to be replaced.

As a rule, it is not difficult to determine that it is time to change the pipe. The most common damage to the corrugations is a violation of their integrity and loss of elasticity of the seals. In both cases, depressurization of the connection will manifest itself in water leakage from the toilet, especially when flushing, and the appearance of a specific smell from the sewer.

A defective place is determined by visual inspection, in a hard-to-reach place — by touch. There are two ways to solve the problem in such cases — repair or replacement of the corrugation. The most reliable is the second, consider it in more detail.

Installation order

The operation of replacing the flexible fitting on the toilet consists of the following steps:

  • remove the old corrugation;
  • preparation of seats for installation;
  • installation of a new flexible pipe;
  • sealing of joints from the outside.

How to dismantle the old connector

If the sewerage system is made of plastic pipes, then the removal of worn corrugations is simple even in a situation where this must be done without dismantling the toilet bowl. To connect the fitting to such a fan system, additional sealants are rarely used, and the dismantling of the adapter is reduced to elementary operations.

First of all, you need to block the flow of water into the toilet and empty the drain tank. The removal of the fitting begins from the side of connection to the sanitary device. The corrugated section is compressed towards the sewer, after which the cuff is pulled off the toilet drain, and the other end of the product is removed from the socket.


When the toilet is located close to the receiving neck, and the corrugation in the working position is already compressed, then to simplify dismantling it is cut across. If the old cuff does not pull off the nozzle, it can also be cut with a hacksaw blade for metal.

On a cast-iron fan system, the place where the corrugations are connected to it can be additionally covered on the outside with a layer of cement mortar or other sealing compound.

Here, when removing the fitting, only those methods are good that will not harm the toilet — the solution can be carefully crumbled with a plumbing screwdriver and a hammer, and the silicone can be cut with a narrow knife.

After the connections with the sewer and toilet are exposed, the fitting is dismantled, and the opened seats are thoroughly cleaned of old seals and sealants, otherwise their fragments will interfere with the tightness of the new connection.

How to install

Install the corrugation in reverse order.

A branch pipe with transverse sealing rings is inserted into the receiving neck of the pipe. It will not be superfluous to apply sealant to the rings before this — this will protect against leakage when the riser is clogged on the lower floors. The folds of the fitting are pressed against the socket, after which the cuff is combined with the toilet drain and pulled onto the pipe — it will be easier to do this if the rubber seal is lubricated from the inside with soapy water.

With sewage from cast-iron pipes, the operation is complicated by the fact that the connection point to it most often needs to be additionally sealed or a special adapter from cast-iron drain fittings to plastic must be installed.

How to shorten a corrugation

Sometimes it happens that the flexible fitting model you like in the store is longer than necessary. The way out is to shorten the corrugation with your own hands, and this is done as follows:

  • the flexible part of the pipe is pulled out of the cuff (the factory connection is glued), and the freed mounting groove is cleaned of glue residue;

  • the fitting is tried on in place and a line of a transverse cut is drawn from the side of the free end;
  • excess length is cut off from the pipe (in reinforced products, bite the wire passing in the folds of the corrugation in a spiral);

  • fill the mounting groove of the cuff with sealant and insert the end of the pipe resulting from the cut there;

  • after the compound has cured, the corrugation is ready for installation.

Important! When shortening the corrugation on the side of the connection to the sewer, the tightness of the joint after gluing will not be ensured, which is due to the profile of the fitting.

After the flexible adapter is installed, to reduce the likelihood of leakage, it is necessary to coat the joints of the cuff with the drain and the outlet end with the sewer neck with sealant from the outside. This will not make the corrugation stronger, but it will increase the tightness of the joints.

Installation errors

The list of mistakes that are made during the installation of corrugations for toilets is small, but all of them are fraught with trouble in the future:

  • Negligence in the arrangement of joints and neglect of additional sealing.

  • Excessive extension of the pipe in the working position.

Increases the tensile load, over time leads, at least, to the sagging of the adapter, and the corrugation rupture is not excluded.

  • Excessive compression of the corrugated part.

Complicates, and sometimes makes it impossible to replace the fitting without dismantling the toilet.

  • Sharp corners in the pipe configuration after it has been installed.

Sharp bends provoke blockages, destroy the corrugation on the outer side of the turn.

Alternatives to exhaust corrugations

If we do not consider home-made devices from improvised means such as reinforced hoses with adapters, then only hard plastic bends Ø 110 mm, the so-called “knees”, are worthy competition for corrugations. Moreover, fittings with solid walls have a number of important advantages over flexible pipes — they are stronger, less likely to clog due to smooth walls and easier to clean from the outside. At the same time, rigid drain fittings are more bulky, and to replace it with an identical one, you need to dismantle the toilet bowl.

To expand the possibilities when placing a toilet in a toilet, solid plastic outlets are available in three types — for vertical, horizontal and oblique outlets.

vertical outlet toilet bowls are equipped in the toilets of private houses, and even then not often. The main inconvenience of such a system is that the sewer pipe must pass through the floor slab.

Direct connection is arranged using one elbow at 90 degrees. or two — at 135.

Horizontal release also called straight — these are toilets, the drain pipes of which are directed back perpendicular to the wall. Such a connection simplifies the maintenance of the sanitary device and visually gives the structure stability, but is carried out with the obligatory use of a sealing cuff.

To equip a horizontal type drain, a coupling and a 135 degree outlet are used.

oblique release implies the direction of the drain at an angle of 30-45 degrees. Today, such toilets are the most popular, because, in addition to an individual installation site, they are also suitable for installation instead of a direct outlet device.

Connection of this type is made in the same way as horizontal — using bends of 135 degrees. and/or straight coupling.

For reference: there are no models with an “oblique” release among the wall-mounted toilet bowls that are fashionable today.


Corrugation will facilitate the installation and connection of the toilet in 9 out of 10 cases. However, experienced plumbers believe that if it is possible to connect with rigid fittings, then it is better to use them.

These arguments are more clearly stated in the video, which will answer other common questions:

In short, solid adapters are stronger and more durable, and this increases the likelihood of depressurization prevention, because such connectors are in most cases visually hidden behind the toilet, and their destruction is detected after a leak.


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