How to Detect Toilet Leaks

Author Info

Last Updated: March 26, 2023 References

Toilet leaks may be easy to repair, but detecting them can be a great challenge, especially when they are completely silent. It's nerve racking to view a water bill and see the amount double or triple what you normally pay for. Here is a very quick and easy method to detect a toilet leak.

Method 1

Method 1 of 2:

Using Food Coloring

Download Article

^{[1]
X
Research source}
Flush your toilet as usual. Wait for the water to rise again to the designated water line of the tank and the toilet to fully complete a flush.

Advertisement
Drop about 4 to 5 food coloring drops in the toilet tank. You may want to use a dark color such as blue or red instead of yellow.^{[2]
X
Research source}
If the water is clear, there is no leak. If the water has changed color, there is a leak present.^{[3]
X
Trustworthy Source

United States Environmental Protection Agency
Independent U.S. government agency responsible for promoting safe environmental practices

Go to source}
This is very important to see if the issue is coming from one specific toilet or happening in multiple ones.

Method 2

Method 2 of 2:

Looking for Other Signs

Download Article

1
Look at the water level. First, remove the toilet tank lid. If the water level is well above the overflow pipe, check the float. The float rises with the water and tells the inlet valve on the ballcock (the float) when to shut off the water valve. If the water keeps flowing past the overflow tube, there is likely a leak.
- To check the inlet valve, flush the toilet and lift the rod that holds the float as the water rises. If you hear the water stop, the problem is caused by the float, and it likely needs to be replaced. A new float and rod are very easy to replace and will only cost a few dollars at the hardware store.
2
Test the flapper. If the water level of the tank is not surpassing the overflow tube, but you still hear or see excess water flowing into the bowl, it’s time to check the flapper. The flapper is a round rubber seal that sits at the bottom of the tank. Its purpose is to stop the water inside the tank from entering the toilet bowl.^{[4]
X
Research source}
- Turn off the water supply valve near the toilet, and check if the water level in the tank decreases. If there is a decrease after 15-20 minutes, the problem could be due to the flapper. There could either be a leak in the flapper, or the chain may be too tight.

Community Q&A

Search

Add New Question

Question

If a toilet slips off the wax seal, will it leak?

Community Answer

Yes, it will leak because the wax ring is what holds the pressure on the toilet. It helps the toilet flush, so if the wax seal is bad, the toilet will seep water out into the sewer. You can tell if the seal is bad by using a wax pencil to mark your water line at night when you go to bed. In the morning, if the water is below the mark, you need to replace your wax seal.

Thanks! We're glad this was helpful.
Thank you for your feedback.
If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow
Yes No

Not Helpful 8 Helpful 26
Question

After I flush the toilet, it makes a hissing noise that's coming from the tank. What could be the problem?

Douglas E. Roberts, Author

Community Answer

The fill valve is not shutting off when the tank gets full of water. Look in the tank to see if water is coming up over the overflow tube. The water level should be just a little lower than that.

Thanks! We're glad this was helpful.
Thank you for your feedback.
If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow
Yes No

Not Helpful 0 Helpful 8
Question

What will fix this problem?

Community Answer

Replacing the "flapper" will usually work. Replacements can be found at Home Depot, Lowe's, Walmart, etc.

Thanks! We're glad this was helpful.
Thank you for your feedback.
If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow
Yes No

Not Helpful 3 Helpful 11

See more answers

Ask a Question

200 characters left

Include your email address to get a message when this question is answered.

Submit

Tips

It may take a few flushes for the coloring to disappear altogether.

Thanks
Helpful 1 Not Helpful 0
If the toilet is flushed during the waiting process, the end results will be inaccurate as the coloring will "bleed" into the bowl from the tank.

Thanks
Helpful 0 Not Helpful 0