Test Your Toilet Flush Valve For Leaks

Toilet Flush Valve

A leaking flush valve in your toilet will allow a very slow flow of water to pass from the tank to the bowl and down the drain. Often the only sympton of this issue is the fill valve opening for a few seconds periodically. Although this won’t cause any damage to your home it will waste a massive amount of clean water. Testing for a leaking flush valve is quite simple.

  1. Die the water in your toilet tank with 2-5 drops of food colouring.
  2. Wait for 10-30 minutes.
  3. Inspect toilet bowl for any sign of died water.
  4. If you find died water in your toilet bowl, your flush valve is leaking.

NOTE: Red or blue food colouring works the best.
NOTE: Existing stains or buildup in a toilet bowl may become tinted from the food coloring.

5 thoughts on “Test Your Toilet Flush Valve For Leaks

  1. Simple but useful advice! I will try this. When we have an issue with the toilet, I guess most of us we need help from professionals to fix it.

    1. Hi Helena,

      Thank you for taking the time to leave us a comment!

      There are several problems that can occur with regards to your toilet. Some are quite easy to fix like a broken trip lever or warped flapper, while others may require the expertise of a professional like replacing a fill valve, flush valve, tank to bowl gasket or wax setting ring.

      If you think your toilet needs to be repaired it certainly doesn’t hurt to contact your local plumber. Toilets problems can lead to a substantial waste of clean water and even worse; severe water damage. If in doubt, call a professional.


  2. Thanks for the tips and it was really great to fix my existing flush valve. But how can I replace my flush valve or toilet flapper? Do you have any easy tips for that. I will be grateful if you take me there with some easy steps..Great post!!

    1. Good day,

      Replacing a toilet flapper is typically very easy. First you will need to pick up a new flapper for your toilet. You can find a large selection of generic/universal flappers at your local hardware store. However, some toilets require a specific flapper not available at your hardware store. In this case you will need to visit a wholesaler that sells your brand of toilet and order it through them. If this is the case it will likely be much easier and faster to contact your local plumber and have them replace it for you. If you are able to locate the correct flapper, simply uninstall the existing flapper and replace it in the same fashion with the new one. Ensure the chain to the trip lever is the same length when reconnecting. Test the toilet fills and flushy correctly and adjust if necessary.

      The same goes for fill valves. If your toilet has a generic fill valve you can likely find a replacement a local hardware store. Ensure you shut off the water supply before attempting to replace a fill valve. You must also flush all the water out of the tank and either vacuum up the remaining water with a wet vac or use towels to soak it up. Any water left in the tank will leak out when you remove the fill valve. Once the tank is empty you can follow the instructions provided with your new fill valve. We also recommend replacing the supply line at the same time. Ensure you backup the valve with a wrench when changing the supply line to avoid putting any kind of excess pressure on the valve as doing so could potential break something.

      We recommend testing your toilet water supply valve before repairing your toilet. Occasionally a supply valve may not work, in which case it will need to be replaced. Also note that the valve may start to leak if it hasn’t been used in a while. Be prepared to shut off the main water supply valve in these cases and contact your local plumber to repair or replace the valve.

      Due to the risks of water leaks when replacing a toilet fill valve we highly recommend having a qualified plumber do this for you.

  3. Great piece of advice, so simple but useful. Will try this advice of yours. Thanks for sharing this, it is so informative and helpful.

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