A blockage in the cistern results in the water flowing continuously after the toilet has been flushed. This is possibly a signal that dirt or limescale is blocking the toilet’s flush valve. The valve is sealed on the outlet at the bottom of the cistern with silicone and stops water from flowing continuously after flushing. Blockages occur when dirt or limescale deposits get between the seal and the drain hole, for example from deposits in the cistern. To solve the problem, all you have to do is remove the flush valve from the cistern and clean it at various places with water or a dry cloth. Then you put the valves back into the cistern and flush once. The video shows how easy this kind of maintenance can be.
How to clean a Geberit Sigma concealed cistern
Installing and cleaning a Geberit exposed cistern
Please be careful!
Be careful: cleaning or descaling the inside of a cistern is tricky. This is not usually necessary and can even lead to larger pieces of limescale or other encrustations becoming detached and blocking everything. If this should happen, a plumber may have to be called in to remove the toilet. You may also encounter problems when removing the trap. A useful piece of advice from experienced engineers is always worth bearing in mind: take a look before you start touching anything. And if you are in any doubt, always consult a specialist.