Cistern seal - this prevents escaping water

A hygienic and functional flushing of the toilet is important to avoid unpleasant odors, to save water and prevent moisture damage preventively. Therefore, it is important that the cistern is well sealed from the start up and remains tight in the later course. But if there are any shortcomings, there are ways to remedy them. The identification of the defect is the first step here and precedes the corresponding repair.

The concrete errors that exist and how they can best be prevented are the subject of the following text.

Possible cistern problems

Basically, there are two major issues that can occur with the density of the cistern. One of them refers to the sealing of the actual box, that is the case. This may be leaking at the interfaces of these items, especially if it is composed of several parts. Also, the transition of the pipes, down to the toilet is affected from time to time by the mistakes. Thus, in this case, the water leaving the system is problematic, which can lead to waste and possibly even water damage or moisture problems in the bathroom.

Further problems may occur with the flushing mechanism. This regulates the water so that it accumulates at exactly the right height in the cistern and only then exits when the flush is operated. Problems often occur here in that the water runs irregularly or even permanently in small quantities into the toilet, without causing this accumulation. Problems with this are the permanent use of water and a poorer rinsing function if there is no accumulation of the right amount of water.

Sealing the housing and pipes

Even though these errors are rare, the possibility is nevertheless too high consider. Turning off the water access is often necessary in order to be able to carry out appropriate work in a meaningful way. After that, the error has to be pinpointed, if that was not already obvious. Fixing the error is another difficulty that is related to the extent. Minor defects can be repaired with special sealing tapes or even with silicone. In some cases, however, the entire exchange is necessary. For single pipes or gaskets this can be done quickly and easily, while the whole cistern is more complex.

Limescale as a general measure

Many problems with cistern seals are due to limescale build-up that causes uneven surfaces Let water penetrate. Therefore, the treatment of the lime is often a measure that can be performed when repairing the cistern seals as a first step. Even if there are enough cases where the lime is not responsible, the cleaning makes sense. This way, the cistern will be clean for years and problems of this kind will be avoided for a long time.

Decalcification is also sensible because it requires neither expensive spare parts nor great knowledge of the flushing mechanism and can be carried out with the simplest cleaning agents.

Changing O-Rings

O-rings are certainly the most susceptible to calcifications, but they can not always be saved by cleaning. Therefore, it makes sense to replace the seal rings, if the error is suspected here and after a decalcification no improvement occurs. The standardized sizes of the rings help with the replacement, but should be determined beforehand to avoid mishaps.

Checking the Floater

Running water into the cistern is not always due to leaking components, but can also be explained by a broken float. This regulates the water level and thus determines how long the water should run into the cistern until sufficient water is available for flushing. If this is broken, there can be two problems with the density. On the one hand, the pressure on the flushing mechanism may become too high, resulting in running water. If this is not the case, problems can be caused by the high water level in the cistern, as the water overflows.

In some cases, there is also a mechanical error in which the flush button and the related mechanism are damaged or jammed. Low resistance when operating may indicate this cause.

Heberglocke as Cause

The most common are running water or other problems with the cistern seal due to the lifting bell. It is a central element and is in principle installed in every conventional toilet. By pressing the switch, it ensures that the water can flow into the toilet. Thus, she is also responsible for the holding of incoming water. Problems can arise here with the Heberglockendichtung or overflow.

Often here only the replacement of individual parts or the entire bell helps, if calcification was not the cause. An advantage of the exchange, however, is that some brands, such as Geberit, for a long time use uniform and non-changing Heberglocken and thus the exchange is much easier. However, there is no manufacturer-independent standard that would simplify the exchange even further.

There is no uniform standardization in this area. However, with the help of type numbers it is easily possible to find the spare parts.


The reasons for leaky cisterns of toilets are very versatile and can usually be explained by mechanical errors or a certain material wear. Simple descaling can sometimes help. Otherwise, it is necessary to replace and replace parts.

Artikelbild: © DmyTo /