There are many different reasons why toilet leaks start to occur, but in general they're predictable.

If your toilet is leaking everytime you flush it the problem is most likely coming from any one of 4 issues:

  • Some nuts and bolts that connect the tank to the rest of the toilet have come loose or have become rusted and corroded
  • The flapper in the toilet tank is not closing and sealing correctly
  • There's a crack in the toilet tank
  • The supply valve has come loose or corroded

The problem could be from just one of these areas or a combination of any of them but these are the 4 most common reasons as to why your toilet may leak when it's flushed.

So, let's go over each one of these problems to find a solution.

Loose Nuts and Bolts

It's more common than you think that those nuts and bolts that connect your toilet tank to the rest of the toilet can come loose or rusted and corroded - especially on older toilets.


You can certainly tighten or replace these nuts and bolts but if the area surrounding them has also become so rusted and corroded - you may need to replace the entire toilet. After all, you don't want a temporary solution here.

Toilet Tank Flapper Is Not Working

Ideally, you should be pro-active and replace the flapper in your toilet tank about every 12 months. They tend to break frequently and it's a very low cost method to save money on your water bill.

Many flappers are made of rubber which can become deformed or deteriorate over time and as a result, they just don't work as well as they used to when they were brand new.


Replacing the flapper is something many homeowners can do themselves, but of course, if you do not feel comfortable doing it then call in a plumber to do the work for you.

There are 3 types of toilet flappers so you want to replace yours with the same type that's already in your tank. You can read more about these different types of flappers to help you know what you currently have and how to determine the type and size that you need to replace it with.

NOTE: Instructions on how to replace each type of flapper can be found by clicking here. Otherwise, below is the basic and general information on replacing flappers.

General instructions to replace the flapper follow these steps:

  • Turn off the water to the toilet by shutting off the valve located on the wall near the base of the toilet. Turn it clockwise to shut it off.
  • Then - flush the toilet and hold the handle down until almost all the water in the toilet is gone.
  • Remove the old flapper.
  • Replace it with the new one that you purchased at the hardware store.
  • Turn the water to your toilet back on by turning the valve counter clockwise.

Here's a video showing you how to replace a toilet tank's flapper. This may not be the flapper you have in your toilet tank so feel free to check out other Youtube videos for instructions on your specific type of toilet flapper.

The Toilet Tank Is Cracked

A crack in a toilet tank is not always easy to spot. Some hairline cracks are so fine, it's just difficult to see them.

So, how can you tell if your toilet tank has a crack? You may have to use a magnifying glass to inspect both the inside and the outside of your toilet tank for cracks. We recommend to start at the points where there are nuts or bolts or seals or anything that is attached to the tank. Cracks can form there more easily than somewhere in the middle of the tank wall.


So if you do find a crack or more the next question is can it be fixed or do you need to replace the entire tank?

The answer is - it depends on the size of the cracks. If it's a hairline crack those can often be fixed tih porcelain epoxy. But if the cracks are larger - then we recommend that you purchase a new toilet tank.

A Problem With The Supply Valve

The toilet supply valve is the valve that controls the hose that connects your toilet tank to your wall. You'll most likely find it near the base of your toilet on the wall behind your toilet.

A leaky toilet water supply valve does not have to mean replacing the entire unit - although that may be a possibility.


If you notice a leak coming from the stem where the handle is located you can try tightening the packing nut with an adjustable wrench. This is the nut located right behind the handle.
Turning the packing nut clockwise will tighten it.

If you still notice a leak then you will have to investigate further by taking apart the water supply valve to clean or replace the washers Shut off the main water supply to the toilet

NOTE: Before you begin, we recommend that you take photos of each step so that you can remember how to put it all back together again

  • Place a bucket and towels under the water supply valve
  • Remove the screw from the handle of the valve
  • Remove the packing nut
  • Remove the threaded valve system
  • Clean the washers with a clean rag or if they are severely damaged then replace them entirely
  • Reassemble everything back
  • Make sure that all components are tightly replaced.
  • Turn your main water supply back on

Toilet leak problems can be fixed easily, most of the time but if you ignore the issue and let it go for too long, the small problem can turn into a very big and costly one so we recommend that you correct any leaking issues that you have as soon as possible.

If you have any questions about toilet leaks or are having some problems with it, call Atlantis Plumbing today at 770-443-8229. We are available 24 hours a day, 7 days a week.