Toilet Leaking from Tank when Flushed only (2022)

Toilet leaking is every household problem. As the toilet ages, new issues emerge gradually. Clogging is the most common, followed by toilet leaking from the tank when flushed only, overflowing toilets, so on.

I completely understand your anguish because I was in the same situation a year ago. Today you are getting the best methods to solve your problem without any plumber.

Toilet Leaking From Tank When Flushed only then the reasons are the Gasket, Flapper seal, and Flexible Socket. To fix the problem, just replace the gasket or the flapper seal.

All of the methods described here have been tried and tested. Before I get to the solution, I would like you to recognize why your toilet is leaking so that you can effortlessly fix it.

Not just for today; all of these reasons and strategies will be useful in the future as well.

Today focus on- The reason behind a toilet is leaking when flushed and how to resolve it.

Why Does Toilet Leak Only When Flushed?

The primary flushing mechanism is when you push the lever/ handle for flush, the water present at the tank goes to the bowl through the flush valve and gasket.

The tank is joined to the bowl through bolts and a rubber seal gasket. 

So, you wondering Why is my toilet leak when I flush the toilet due to THE GASKET

The Spud washer or the gasket is present between the bowl and the tank joint. It is generally made with rubber and seals tight the junction.

Whenever water enters the bowl through the flash hole, it prevents the water spatter.

If the gasket seal is damaged or loosened in any way, there is a 100 % chance each flush will result in a water leak.

Why is my toilet flowing around back after each flush- Because the FLEXIBLE SOCKET

The flexible socket is present behind the toilet pot near the wall. Oh, this is found only the drainpipe goes through the wall, not the floor. 

The flexible socket is another sealer place that attaches to the main drain pipe. All waste materials pass by it. 

When a toilet is aged and long time used, the flexible socket becomes thin and turns by using lots of toilet cleaner.

Meanwhile, each flush water runs through it and leak from the socket pipe, and you see water leak around the back after each flush.

Another possible reason for the toilet leak when flush -THE FLUSH VALVE SEAL 

In this case, you may notice the water split out from the back area whenever using the toilet.

The flush valve seal is another powerful seal part present in the tank bottom. It prevents water leakage when flush also can protect the water when not flush.

If the Flash valve seal is not in the correct position or has cracks, the toilet may leak when used after it has been flushed.

So, here you go. These are the possible cause of any toilet that leak when flush.

Now time to fix this problem.

How Do You Fix A New Toilet Leaking From Tank When Flushed only?

If the Gasket is Main Cause, then replace it.

How to replace a gasket from the toilet to prevent leakage

It would be best if you first detached the toilet tank to replace the bowl gasket. Can tighten the bolts present near the gasket. Replacing a new one is a more convenient result.

To remove the gasket, buy a new one. You can use Fluidmaster Tank to bowl gasket kit ( get all kit like-bolts, gasket 4.72 x 1.38 x 6.69 inches). 

Follow the step- Can tighten the bolts present near the gasket.

1. Shut off water lines to the toilet

To detach the tank and the bowl, you need to drain all water from the tank. So at first, shut off all water supply lines towards the tank. 

2. Clear the water from the tank

You must drain all water from the tank in order to remove the tank and bowl. Flush once, then remove remain water with the help of a sponge or old cloth.

3. Detached the water pipe

After draining down all water, detached the water pipe from the tank. 

4. Unscrew the bolts

Two bolts are present at the bottom of the toilet tank, which provides security and seals the tank with the bowl. Unscrew it with the help of a wrench.

5. Now time to pull up the tank

After unscrewing the bolts, the tank gets loosen, so be careful of that. Life up securely and place it on a towel to prevent any scratch.

6. Remove the Gasket

Now you can see the gasket (red, black, blue color differ). Remove it and replace it with the new one. Clean the area surrounding the Spud washer.

7. Last step so important

  • Place the Gasket. 
  • Place and tighten the bolts again.
  • Place the tank in its place.
  • Attached is the water supply line.
  • Turn it on, check the water level is normal or not.
  • After filling the tank, flush once to test further leakage is present or not.
  • If the Gasket is the cause of the toilet tank leaking after every flush, replacing it can solve the problem. If, not then the gasket is not the thing you look for.

How to Replace a Flush Valve from the toilet tank to Stop Leakage 

Flush Valve is the present bottom of the toilet, precisely beneath the flapper.

1. To replace the Flush Valve, at first shut off the waterline and flush completely. Exclude leftover water by using a sponge or cloth.

2. To remove the flapper, disconnected the chain and flapper arms.

3. Pull up the flapper you can see a wax ring present there, replace it with the new one.

4. Do the process vice versa.

5. After filling the tank, flush once to see if there is any additional leakage.

This way, you can quickly resolve your problem.

Final Verdict Toilet Leaking From Tank When Flushed Only

If you chose to do it yourself, a toilet that leaks when flushed could be effortlessly repaired at a low price. 

If you try to fix it yourself and fail, you can still call a qualified toilet expert.

We don’t care about the toilet that way until it shows a problem. Still, if you notice it, then you avoid tiny obstacles. It turns into a significant mess.

Consequently, the seep will become worse and lead to water damage or even disaster if left ignored for long periods.


· Do not dismiss the issue. 

· Make sure the nuts on the toilet’s base are securely fastened. 

· Examine the wax ring beneath the toilet. 

· Look inside the toilet tank for a leaking gasket or water.


Q1. How Do I Know If My Tank Gasket Is Leaking?

When a toilet is leaking behind it, particularly after flushing, 90% responsible reason is the Gasket. 
If you look out for the source of the leakage thoroughly, you may notice its leaks beneath the gasket.
This way, you may know there is a problem with the gasket.

Q2. How do I check if my toilet is leaking?

There is so easy yet no-cost method present for check if a toilet leaks or not.
1. Remove the tank lid.
2. Add a few drops of food color.
3. Wait for few minutes
4. If it leaks without flushing, the color appears at the bottom of the bowl. 
5. If not, the color stays at the tank when you flush; the water becomes that color and goes down like normal.
6. You can use dye color instead of food colors.

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