Easy Toilet Dye Test – How To Know if Your Toilet Is Running

By Mengning Heil

May 27, 2022

Toilet Plumbing Tips

Reading Time: 2 minutes

Today, we’re going to show you how to perform a toilet dye test to know if your toilet is running when it shouldn’t be.

How To Know if Your Toilet Is Running

In some cases, you may be able to hear the sound of the toilet running. This is the sound of water leaking from the tank, where the water is stored, into the bowl. However, if the tank leak is slow, you may notice an abnormally high water bill before you ever hear indications of an overactive toilet. If you see an anomaly in your water usage, a running toilet is among the first things to check, and it will only take ten to twenty minutes! 

Toilet Dye Test – Instructions

To perform a toilet dye test, all you need to do is take the lid off the toilet tank and drop a few drops of dye into it. (Food coloring works well.)

picture of the performance of a toilet dye test
Drop a few drops of dye into the toilet tank.

Now, just wait! In ten to twenty minutes, if the toilet tank is leaking into the bowl, you will see dye appear without flushing.

how do you know if your toilet is running and the tank water is leaking into the toilet bowl
Wait 10-20 minutes and check to see if the dye has leaked into the toilet bowl without flushing.

If the toilet is very old, it could need to be replaced. However, a leaky toilet tank is more likely to be an indicator that you have a toilet flapper leaking (check out the video tutorial), a simple DIY project even for beginners!

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If you need help with leak detection in Rockville or the surrounding areas, connect with a trustworthy plumber in Rockville, MD by contacting Heil Plumbing today.


Heil Plumbing is a family-run company owned by a third-generation master plumber. We can help you with a full range of plumbing services, including toilet installation and repair, leak detection and pipe repair, water heater repair and installation, faucet repair and installation, drain cleaning, water treatment services, and more.