How to Fix a Cracked Toilet Tank? (From Hairline to Big Crack)

Written by

Paulk Webb


Freddie J. Hagopian

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how to fix a cracked toilet tank

No matter how you care for it, a time comes when your toilet tank breaks and suffers cracks you never want to have. A tank breakage at whatever stage causing a leak always becomes a source of worry as it affects how you use your toilet properly.

From a hairline split to a very visible fracture, how to fix a cracked toilet tank need not be your greatest worry.

Various ways can be easily taken to fix any crack issue and get your toilet tank up and running again.

Ways to Fix a Cracked Toilet Tank

Determining first the extent of damage to your broken toilet tank must be the first step.

For instance, to repair only a cracked porcelain toilet tank lid isn’t much to worry about. However, you should fix it immediately to prevent worsening issues.

Steps and Ways to fix that cracked toilet Tank

There are basically 2 ways to fix a cracked toilet tank. One is through repair and the other is through outright replacement.

1. Cracked Tank Repair


You should choose a quality waterweld toilet tank epoxy with good adhesive to bond the porcelain tank well. It’s best to go with recommendations from experts.

Materials and tools:

  • Plumbing Epoxy or waterproof epoxy for toilet tank
  • Silicone Caulk or rubber sealant
  • Rag o towel
  • Putty Knife
  • Hairdryer (optional)
  • Masking Tape


  1. Shut off your toilet tank’s water supply valve, then flush your toilet once.
  2. If the crack is easily visible, mark the exact spot where the crack starts and stamp with a masking tape an inch above it.
  3. With a towel or rag, clean and dry the area where you would apply the epoxy or sealant. Using an epoxy for toilet tank repair is an excellent first option.
  4. For the epoxy, mix similar amounts of the waterproofing compound per manufacturer’s instruction.
  5. Using a putty knife, apply the compound on the crack’s surface starting from the top going down. Let it cure for a good 25-30 minutes.
  6. For some epoxy brands, overnight is needed for optimal curing. You may hasten the curing by using a hairdryer.
  7. If cracking results in enamel getting chipped off, you can use silicone caulk to fill in the area. Crevices where possible leakage happens may also be filled in.
  8. To check for leaks, fill the tank with water and monitor any drips appearing.

If you use a heavy duty rubber sealant, follow the steps but use the sealant instead.

2. Cracked Tank Replacement


You must seriously consider replacing your toilet’s tank if the crack or fracture penetrates fully into the enamel. Such cracks are already too big to repair and most likely will deteriorate rapidly with use.

When replacing your tank, make sure that your new tank’s design and color fits well with the bowl.

Materials and tools:

  • New toilet tank
  • Pipe wrench
  • Screwdriver (as needed)


  1. Flush the toilet tank to remove water. Loosen carefully the tank base at the bolt anchor using a screwdriver.
  2. Replace it with a new tank per manufacturer’s instructions.
  3. Use a pipe wrench to tighten hose connections. Test your new tank by filling it with water and checking for leaks and drips.

Frequently Asked Questions


What causes hairline cracks in toilet bowl?

Sudden impact by a hard object primarily causes hairline cracks appearing in the toilet tank and bowl. The appearance of these minute breaks is also influenced by the deterioration of the porcelain enamel caused by age and temperature.

Can a toilet bowl crack on its own?

Two reasons explain why a toilet bowl and tank break on their own. Even the tough porcelain does not guarantee against cracking.

  • Age is one factor. While a toilet’s porcelain material could last up to 50 years, natural deterioration is unavoidable.
  • Temperature variations also cause porcelain to break or crack. Extreme and sudden changes could affect porcelain integrity.

Can cracked toilet tank be repaired?

Yes! Proper knowledge of home DIY tasks could save you time and money for that needed toilet tank repair. Using porcelain epoxy for toilet bowl repair is even recommended.

Benign cracks appearing above water lines both in the tank and bowl cause no leaks initially. Regularly checking them prevents serious problems later.

When you have that toilet set that is both durable and priced right like Glacier Bay, repairing may come as a very practical option. You may use a toilet tank repair kit for it.

If it’s an American Standard 4215a tank that cracked, you may consider replacement immediately. Toilet parts are always available.

Can Flex Seal fix a cracked toilet tank?


Flex Seal rubber sealant helps fix your toilet tank against any leak. It is made from a super adhesive compound good for various applications.

Be it on tiles, plastic, wood, concrete, and even metal, it works wonders to provide you that strong bond and sealing properties.

In fact, your porcelain toilet tank and bowl gets a new lease in life with proper Flex Seal assistance.

Which option is better, repair or replacement?

For long term service and durability, replacement with a new tank remains the better choice if you have dollars to spare.

When you fix the hole in toilet bowl or you repair your porcelain toilet tank lid, both options are okay but remain prone to further cracking.

As mentioned, a factor to consider is your toilet’s age. If the bowl has been in service for years, consider replacement as the only option.

If you choose to swap a new piece, just carefully follow the proven and tested steps to undertake that replacement task yourself.


With proper monitoring, your toilet bowl and tank’s integrity against cracking could be regularly checked.

Determining how to fix a cracked toilet tank need not be a serious problem demanding a tedious solution.

The steps you need to follow are just really easy and simple. Guided by these simple tips on getting it done, fixing your toilet bowl and tank gives you that peace of mind in every trip to your comfort room.

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