Why is there an overflow in the toilet cistern and what to do?

In every house, a toilet bowl is considered an indispensable element of everyday life, since you cannot do without it. Compared to other plumbing devices, the toilet is used much more often, so it quickly breaks down.

The tank is considered the most vulnerable part of this device; if it malfunctions, many have to deal with the problem of water overflow, which it is quite possible to solve on their own (without calling a team of plumbers).

Main reasons

Everyone is familiar with the situation in everyday life, when water is constantly collected in the tank, it overflows, but this process continues – the flow does not stop. If the overflow of water in the tank is not eliminated in a timely manner, then this plumbing device can quickly break down. To prevent this from happening, it is necessary to take timely measures to eliminate breakdowns, having previously clarified their causes. The water in the tank overflows mainly due to improper adjustment or depressurization of the float, which few people pay attention to. In addition, there are other causes of breakdowns..

  • Malfunction in the reset system. All modern cisterns are manufactured with a bottom connection and a drain button. If the system does not turn off the fluid set or drains it poorly, then the drain valve is to blame. It is quite simple to identify this: first of all, restrict access to the water supply to the tank, then look at the overflow. If all the reasons lie in the valve, then the water will flow out until the container is empty. Leakage is usually observed due to the ingress of foreign particles between the drain and the outlet valve seat, they form a small gap, and liquid constantly appears through it.
  • Rubber valve wear. With long-term use of plumbing equipment, the pear begins to lose its elasticity, since the rubber coarsens and does not adhere tightly to the surface of the saddle. As a result, water will constantly flow out and be collected into the tank..
  • Breakage of the emergency tube. Used in the system to empty the tank from excess fluid. If it is out of order, water will start to continuously collect and drain directly into the toilet..

Eliminating the problem

Any malfunction in the operation of the tank can be quickly eliminated without the help of specialists, and the breakdown associated with overflow is no exception..

  • Incorrect float setting. Correction of a malfunction in this situation directly depends on the model of the locking mechanism. If an old modification tank is installed in the bathroom, where the float and the shut-off valve are interconnected by a metal lever, then it is enough just to bend the lever manually. In products where it consists of two plastic parts connected by a bolt, it is recommended to loosen the bolt slightly, then change the angle of inclination between these two parts and tighten it again. All work is performed after dismantling the tank lid, for this you first need to remove the ring that serves as a frame for the drain button.
  • Depressurization of the float. If there are no problems with adjusting the float, then it is necessary to additionally check how it floats to the surface of the water and how the shutter mechanism works. When the float is completely immersed in the liquid, then there was a depressurization. It is eliminated by replacing not only the float, but also the entire stop valves. To do this, the water supply is completely shut off, the remains are lowered into the toilet, the flexible piping, shut-off valves are dismantled, then new elements are installed.
  • Wear of rubber pad. Since this part is responsible for sealing the flush hole, the resulting rupture can lead to a weakening of the density and, accordingly, cause a leak. In this case, replacement of a new gasket is required. If the exhaust valve is deformed at the same time, then you need to replace the whole mechanism.


Overflow is considered the most common problem when using plumbing fixtures. It is necessary to eliminate such a malfunction correctly, starting with finding out its cause, otherwise time and effort will be wasted. If you plan to repair the tank yourself, then you should take into account the recommendations of experienced craftsmen.

  • The first step is to carefully study the instructions, it is attached by the manufacturer to each device. If this is not done, then you can incorrectly perform the actions and break the tank, and the acquisition of a new design will be expensive..

  • All work related to the repair must be carried out carefully, otherwise you can break not only the accessory itself, but also other parts. It is necessary to start repairs with checking the operation of the tank. The overflow hole in the structure must be open – it must not be completely plugged. If you do this, water from the tank will overflow onto the floor and ruin the repair.. Before proceeding with the diagnosis, you need to turn off the water and let the tank dry completely.

  • If it is impossible to reach the drain mechanism without removing the tank, it is recommended to dismantle it. To do this, unscrew the fasteners located at the bottom of the device..

      • To avoid overflowing the toilet cistern, you should periodically check the condition of its fittings and carry out preventive measures, the main of which is the cleaning of the inner surface and all parts from red plaque. Limiting the entry of various contaminants into the tank will help equipment for internal wiring with filters, they need to be located next to the riser for the cold water supply.

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