How to Fix a Cracked Toilet Tank – 6 Easy Steps

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Toilet tanks are constructed to withstand and handle high levels of water pressure. Despite our efforts to keep it intact, it does occasionally crack.

Toilet tank cracks, particularly hairline ones, can form over time. In situations like these, it is particularly important to take action right away. You won’t want to wait until the tank cracks leads to water explosions; otherwise, you will have only one option to make it function. i.e., replacement.

For major problems, it is best to call a plumber, but you can fix the less complicated issues on your own. Here are instructions on how to fix a cracked toilet tank.

How to Fix a Cracked Toilet Tank

How to Fix a Cracked Toilet Tank

Accidents can lead to cracked toilet tanks from time to time. When reattaching the lid, you dropped a heavy object on the tank. This problem can be corrected without the help of a professional by following these steps.

Here’s what you’ll need

It’s best to have the materials you need on hand when working on your toilet. It would be best if you’re weren’t running back and forth to the bathroom in the middle of an installation or toilet tank repair. In that regard, here are the supplies you will need to fix your cracked toilet tank.

Step 1: Turn off the water

In the absence of a visible leak, you may ignore this step, but it is still advisable to turn off the water. The water should not be spraying everywhere and causing a mess, so shutting it off is the best solution.

It is easy for water to leak from a cracked tank and flood the floor. As a result, you might run into even worse problems if you don’t turn off the water before starting the tank maintenance.

Furthermore, turning the water off isn’t an issue that takes much time. Behind the toilet is a water shutoff valve that can be turned off in less than five minutes.

Step 2: Dry the inside of the tank

To fix cracks in your tank, you need to seal it, but if it’s wet, the sealer will not dry out. For this reason, make sure that the tank is completely dry before you begin working on it. A faulty sealer can cause all the work you put into something to be for nothing.

I agree that drying isn’t fun, but it’s a necessary step. Chamois cloth, sponges, towels, or any type of material that absorbs water is acceptable. Ensure that the outer surface of the tank is also wiped, otherwise, condensation may occur.

Once you’ve washed the tank and sponged it thoroughly, you can even use a hairdryer to dry it completely. By doing so, you are assured of a completely dry toilet tank.

Step 3: Apply silicone plumbing epoxy to the cracked area

Epoxy sealers can be easy to find. Ceramic sealants can also be used. It is likely that you will be surprised by the many choices. To get the best results, consult a plumber about the right brand.

Depending on the caulking gun you bought, you may need to use it with the sealer. Use a gun to seal the cracks and apply the sealer. Start filling the crack with sealant about one inch above the crack and then work your way downward.

When you use a waterproof epoxy material, it usually comes in two parts, which need to be mixed together. It takes 15 minutes or 30 minutes for epoxy to harden. Opt for a porcelain-safe epoxy.

Putty remains soft as it cures. This makes it easy to shape and form. That means that while the putty is still soft, you can push it into a crack, then the hardening putty will seal the crack.

Note: If you attempt to repair toilet tank cracks under the waterline by using epoxy, please be aware that this isn’t always an effective solution. When this happens, you have no choice but to replace the cracks.

Step 4: Smooth the sealer out

Use a paper-knife, putty knife, or any other tool capable of spreading the sealer over the crack to spread the sealer over the crack as widely as possible. Even if it has cracks, you can still use this method to maintain the appearance of the toilet. Furthermore, applying the sealant evenly will help to prevent cracks from spreading.

Step 5: Allow the silicone epoxy to dry

Before removing the sealant, let it dry out and seal the cracks and crack lines for at least 24 hours. Furthermore, you should also keep an eye on the areas you sealed regularly to see how they progress.

Knowing other glazing cracks will help you address them in a timely manner as well. It is safe to fill your tank with water once you are done applying epoxy and no other cracks appear.

Step 6: Refill the tank with water

Activate the water supply in the tank once again. Inspect the tank after being filled with water to determine whether leaks persist. In the event that leaks persist, you will have to empty the tank of water again and double-check the repaired spots. Verify that there are no other leaks.

Despite being built to last, toilet tanks do not necessarily stay in good shape forever. Just make sure we don’t allow the problem to escalate, and the problem will be sorted out in due course.

How to find cracks in toilet tank

Cracks may appear on the inside and outside of a toilet tank, as well as in the bottom of the tank. What needs to be done depends on the location of the crack. Read on to find out what to do.

1. It is not unusual for cracks in the upper water line to be ignored unless they grow slowly over time. Keeping an eye on bathroom cracks is a good idea if you notice one. If you wish to compare the crack later, you should take a picture of it.

2. Cracks below the waterline will need to be repaired. Cracks beneath the waterline can be hard to spot. If you suspect that there is a leak from the toilet tank, check the seals between the tank and bowl. Next, make sure that the porcelain tank does not seem to have cracks. If needed, inspect the tank from the inside and the outside.

The causes of toilet cracks

1. Firstly, let’s look at some obvious points. Someone dropped something on the toilet. Is that a heavy object? Has anyone slipped in the bathroom? This result can be plumbing problems such as damaged or leaky toilets.

2. DIY renovations could result in cracks. The porcelain in your toilet may appear durable, but it can easily be damaged by an accident during a homemade repair. Likewise, when bolts are overtightened, they can crack the tank. If you are returning the lid to the toilet, be sure to lay the lid down gently. If the lid drops suddenly, it could crack the tank. Sometimes it is best to leave toilet repairs to the professionals.

3. Cracks due to aging. It is inevitable that everything will wear out. Aged toilets are at greater risk of cracking. As you clean your bathroom, notice any wear and tear on the toilet and keep your eyes peeled for any suspicious leaks cause by emerging cracks.


The design of your toilet is probably not something you’ve paid much attention to, but when water starts leaking out, you should pay attention. A complete guide on how to fix a cracked toilet tank is the best way to deal with such a situation.

If the crack on your toilet is larger than 1/16 inch, it may be best to just replace the damaged toilet rather than attempting to repair it. It is always recommended to call a professional plumber for larger leaks and replacements.

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