What causes a toilet to keep running

The toilet cistern continues to run: this is how you solve the problem | manual

It runs and runs and runs: a leaky, splashing toilet flush is annoying and can drive up your water bill. Usually the problem is in the cistern itself - but it can be easily fixed.

Stiftung Warentest did the math: A broken toilet cistern lets a lot of water drain away unused. Just one drop per second adds up to several cubic meters over the course of a year.

To prevent the water from running in the toilet flush, the experts recommend looking into the box and checking its functional parts: Are they damaged or soiled? In most cases, this is due to a worn seal on the so-called lifting bell - a plug that is lifted during the flushing process so that water flows - or a defective inlet valve.

Jammed float: water continues to run

A so-called float regulates the water level of the inlet valve and is often responsible if the water inflow no longer works correctly. The float is usually located on the surface of the water in the cistern. When the water level in the cistern reaches the maximum level, it normally closes the valve and thus stops the water flow.

However, if the swimmer is caught, this can result in either no water flowing in at all or too much water flowing in. Hit the closed cistern lightly once. So the swimmer may come loose. If the blow doesn't help, you should open the box.

Step 1: Turn off the water supply

Before opening a cistern, turn off the water supply to prevent flooding in the bathroom. You can usually find the tap on the wall next to or behind the toilet. Close the small angle valve, usually located on the side of the cistern, and use it to shut off the water supply. Now empty the cistern by pressing the flush button.

Step 2: Open the cistern lid

The cistern is above or below the plaster of the wall. Either the cover of the box is pinned on or it is screwed on. You can open an attached cover. Use pliers if you can't do it with your hands. Loosen the screwed covers with a screwdriver. Once you have removed the cover, rinse so that you can see the mechanics better.

Step 3: Take out the functional parts and clean them

To prevent water from flowing in, clean the functional parts of the cistern and replace the porous sealing rings. The experts from Stiftung Warentest recommend grasping the lifting bell as far down as possible with one hand, loosening its bayonet socket with a slight turn to the left and lifting it out at the top. Buy a set of O-rings for your cistern model from your hardware store and prepare a bowl of vinegar cleaner or descaler at home.

Our tip
Make a sketch of the mechanics of the toilet box so that you can insert all the parts properly later.

Use the pliers to pull down all visible rubber seals from the functional parts and remove the sieve from the supply line. Then put all the dismantled parts in the prepared bowl for descaling and cleaning. After two hours, take the individual parts out and clean them with a household towel.

Step 4: reassemble the cistern

You can put the cistern back together using your sketch. First replace all removed rubber seals with the new sealing rings. Use pliers again to pull the seals onto the functional parts. When reassembling, connect the seals of the dismantled parts according to the sketch with the connections and devices provided. It is important that the bayonet lock engages securely and that no sensitive plastic part breaks.

Important:Be careful, otherwise the toilet may overflow the next time you flush.

Step 5: check the water level

Before you assemble or screw the cover for the cistern together, you should check the water level. To do this, open the corner valve on the side so that water can flow in again. A rule of thumb applies here: if the water level inside the container remains below a marking line, everything is okay. If it rises above it, you can readjust a vertically attached adjusting screw on the float. It is advisable to stay a few centimeters below the mark so that water can also be saved in the long run.

Step 6: start the test run

After the cistern is closed again, rinse once. If the water continues to run, it may be because the float valve no longer closes safely. There are also replacements for this. Complete float valves are available in stores from ten euros. According to Stiftung Warentest, the replacement is just as easy as replacing the seal. If you continue to have problems, you should ask an installer to carry out the repair.

Extra tip: Descale the cistern

Even if the water does not continue to run in the cistern and it is fully functional, ugly limescale will build up on the inner walls over time. One reason: water that is too hard. The deposits can often be removed with home remedies. It is best to wear cleaning gloves for this.

citric acid

  1. Dissolve two to three teaspoons of citric acid powder in lukewarm water (below 40 degrees). Alternatively, you can also use liquid citric acid. Pay attention to the instructions on the packaging for the mixing ratio.
  2. Fill the acidic solution into the open cistern filled with water.
  3. Let this work for several hours. Tip: Preferably overnight!
  4. Then press the rinse button and check whether the deposits have loosened.
  5. If necessary, you can now easily remove residues with a dishwashing sponge.

Vinegar essence

  1. Mix the vinegar essence in a ratio of 1: 4 with hot water.
  2. Pour the acidic solution into the filled cistern.
  3. Let it work for about an hour.
  4. Then press the rinse button and check whether the deposits have loosened. You can also use a sponge to help here if necessary.

Important: You should only use vinegar essence if there is no metal installed in the cistern. The reason: some alloys do not tolerate acetic acid. It can attack the material. Vinegar essence can also damage rubber seals.

Denture cleaner

Because of denture cleaners is only something for the third party. In fact, a cleaning tablet can be used in many ways, for example to decalcify the soda maker, but also a cistern:

  1. Put three to four tabs in the filled cistern.
  2. It is best to leave this on overnight.
  3. Press the rinse button in the morning. If the deposits have not yet dissolved, repeat the process.

If the home remedies do not bring the desired effect, try a chemical descaler from the drugstore. Make sure, however, that it is largely environmentally friendly and carefully read the instructions for use and warnings on the packaging.

Regardless of whether you want to decalcify the cistern with household remedies or chemical cleaners: press the flush button several times after each procedure so that possible acid residues are rinsed out and the plastic of the cistern cannot attack.