Toilet Leaking from Tank When Flushed: Explained 3 Reasons

Every time you flush your toilet, water trickles from the back of your toilet tank and flood the bathroom floor.

Leaky Toilet! Yes, it’s a common but frequent plumbing issue every homeowner faces. The issue- toilet leaking from tank when flushed may occur for multiple reasons, like:

No matter what the cause behind the leaky toilet, it can bring serious damage to your bathroom. If you don’t fix it immediately, it may become a costly problem. So, you should repair the toilet leak as soon as possible.

In this guide, we break down some issues that are responsible for toilet leaks. Also, we provide possible solutions to fix the leaky toilet.

Toilet Leaking from Tank When Flushed

3 Reasons and Solutions of Leaky Toilet Tank

From this chapter, you learn about every possible issue that is responsible for the leaky toilet tank and solutions to them.

Reason 1. Bolts that hold the tank on the bowl come loose

The first reason that allows your toilet tank to leak water is the three bolts that keep the tank in place on the bowl. If somehow those bolts may come loose, water can easily seep into them and leak when you flushed. Therefore, the loose nut and bolt that hold the water supply line in place may be another reason behind the leaky toilet tank.


Disassemble your toilet and then use a screwdriver or a wrench to tighten the bolts that keep the tank on the bowl. We also suggest you screw the water supply line tightly. If still the tank leaks, it would be better to replace the tank with a bowl gasket and supply line washers. Make sure you prevent yourself from over-tightening those bolts. Otherwise, it will bring damage to your toilet.

Reason 2. Faulty Flapper

If the flapper of your toilet is not fitted correctly where it is supposed to be, your toilet will not run smoothly. You may ask- how can I understand whether the flapper is well or not?

Simple, just drop some food coloring into the tank and wait for a few minutes. If the coloring leaks into the bowl without flushing the toilet, then understand your toilet flapper is in problem.


First off, turn the water supply off by switching off the shutoff valve. Then, flush your toilet until the last drop of water escapes from your toilet tank. Secondly, mop the toilet tank with a sponge and remove the remaining water on the floor.

Thirdly, pull out the tank lid and check the softness of the flapper. If you feel it hard, replace it with a new one. You can find the flapper in your local hardware store.

To replace the flapper, first, pull the old one and detach it from the flush handle. Then, install the new one and attach the flapper to the flush handle chain.

Finally, turn the water supply on and let your toilet tank fill.

Reason 3. The toilet gasket is faulty

Whether your toilet gasket is in problem or not, you need to take apart the entire tank from your toilet. The bad news is- you need someone to help you as the tank is bulky and you alone can’t manage the weight. However, you can hire a plumber to do this trick. But you don’t want to spend a single penny, check out the solution section on how you can check the gasket.


Firstly, turn the water supply off and flush your toilet unit, the rest of the water is emptied. 

Secondly, use a wrench or screwdriver to unscrew the nuts that hold or keep the hold-down bolts in place.

Thirdly, with the help of the wrench, unscrew the jamb nut also that keeps the water supply line secure to the tank.

Then, remove the tank with the help of your friend from the toilet bowl.

Next, check whether the rubber gasket is in good shape or getting cracked. If it gets cracked, replace it with a new one.

After changing the gasket, put your toilet tank in its place and turn the water supply on.

Finally, allow your toilet tank to fill with water.

More on LivingProofMag
Eliminate the Urine Smells from your Toilet
Toilet Smells Even After Cleaning
Why Is My Toilet Making Noise When Not In Use
How to Unclog a Toilet Full Of Poop and Water


How do you fix a toilet that is leaking from the tank?

There are several reasons behind a leaky tank. How you fix the leak depends on the source of the leak. For example, if the gasket of the toilet is in problem, you should replace it. On the other hand, if the flapper is faulty, you must change that. So, try out the solution we provided.

How much does it cost to fix a leaking toilet tank?

On average, you need to spend around $100-$600 to fix a leaky toilet tank.

What causes water leaks around the base of the toilet?

If the seal under your toilet fails, it causes water to leak around the base of the toilet.

How much does a plumber charge to replace a wax ring?

Typically, a plumber may charge around $50-$200 to replace a wax ring including the labor and equipment.

How do I know if my wax ring is leaking?

If you notice the following issues, then understand your wax ring is leaking.

  • The water may seep out of the toilet base
  • There may have water stains on the ceiling and the floor


We hope you get the solution to this issue: Toilet leaking from tank when flushed.

Faulty gasket, flapper, or water supply line are the reasons behind the leaky toilet tank.

To get rid of this issue, try out every solution we provided above. After trying out every method if still the tank leaks, probably there is a serious problem in your plumbing system.

In this case, we recommend you hire a certified plumber to help you out. 

If you have any questions related to this topic, don’t forget to check out the FAQs section.

Leave a Comment

Your email address will not be published.