Why does my toilet water keep running?

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Wondering why your toilet water keeps running? This is one of the most common problems you may encounter with a toilet.

Below are four tips to resolving the issue:


The flapper refers to the rubber or plastic cap that prevents water from escaping from your tank. Over time, flappers may become hard, leading to an imperfect seal. If you find that your tank isn’t refilling properly or holding water, then the most likely cause is a faulty flapper. Follow these steps to troubleshoot your toilet flapper:

  • Examine the flapper. Toilet flappers often become brittle with age and this will result in them being unable to form a perfect seal. Check that the flapper feels soft and can hold the water back in the tank.
  • Check for jams. Sometimes flappers get caught around the hinges, which can also prevent a perfect seal.
  • Examine the chain. Check to see if the chain attached to the flapper is not caught on anything. If the chain is really long, taking out some of the excess will prevent tangling from occurring. If the chain is it’s rusting, it should be replaced.
  • Check the alignment. Flappers can become dislodged and this can cause leaks. Ensure that the flapper is sealed directly above your drain.
  • Check for mineral deposits. Mineral deposits can accumulate on your flapper which is another thing that can prevent it from forming a proper seal. If you notice any deposits, clean it by soaking it in vinegar, then get a brush and scrub it to dislodge any residue.


The overflow tube in your tank prevents it from overfilling and flooding. However, if the float cup is too high then some water will enter your overflow tube and go into your bowl. This will result in your fill valve periodically turning on to top up your tank and the toilet water will keep running.

How to adjust your water level:

  • Lower your fill valve’s float setting. Your valve may come with a rod and clip. You will need to squeeze this to slide it up or down the rod. If you need to lower your water level then slide your clip down.
  • Flush your toilet then allow it to fill back up and stop
  • Check the level of the water. The level should be approximately ½ to 1 inch lower than the top of your overflow tube
  • If necessary, continue to adjust the float and flushing until the tank fills up to the correct level.


If your float has become waterlogged, this can also cause the toilet to run. If there is water trapped in the float then the float will sit lower in the water than recommended. This will leave the float valve open. To check the float, simply unscrew it and shake it. If you hear water moving around inside then it will need replacing.


The water flowing into your tank is controlled by the fill valve. If it is broken then it may not shut off the supply and this may cause your toilet water to keep running. The main sign of a faulty fill valve is a submerged float valve. Fill valves are cheap and simple to replace.

Replacing a fill valve:

  • Close your shutoff valve. Turn off the water supply. Then, take off the lid of your tank and give your toilet a flush to empty it.
  • Remove the water supply hose. Put a container (such as a bucket) underneath the supply hose and then disconnect it from your fill valve located underneath the tank.
  • Take out the broken fill valve. Any water left in the tank will go into the container that you have placed underneath.
  • Place the new fill valve in your tank and adjust its height to fit your tank. Insert the threaded end of the valve into the hole in the tank. Secure the valve using your locking nut and tighten it by hand.
  • Connect the supply hose to the fill valve, then tighten well. Clip your hose to the top part of your overflow tube and make sure the hose points into your tube.
  • Turn the water back on and allow your tank to refill. If necessary, adjust your water level to the level specified by your manufacturer.

If you are in any doubt then get in touch an we will be happy to help.

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