A cracked toilet tank can cause leaks, wasted water, and expensive repairs if not fixed quickly. The good news? Small cracks can often be repaired with the right materials, saving you from replacing the entire tank. However, if the crack is too severe, a replacement tank may be the best option.
In this guide, we’ll walk you through how to inspect your toilet tank, repair minor cracks, and know when replacement is necessary.
Can You Fix a Cracked Toilet Tank?
Yes, but only if the crack is minor. Hairline cracks that don’t leak can often be repaired using epoxy or porcelain sealer. However, deep cracks or those near the base of the tank will continue leaking even after repairs, meaning replacement is the safest option.
How to Determine if the Crack Is Repairable
Before attempting repairs, it’s important to determine if the toilet tank cracks are repairable. To do that, you need to identify the severity of the crack.
Step 1: Inspect the Tank
Before deciding whether to repair or replace your toilet tank, you need to assess the severity of the crack by inspecting the toilet tanks. A quick visual and tactile inspection can help determine if the crack is superficial or deep enough to cause leaks. Follow these steps to examine the damage.
- Examine the outside of the toilet tank under good lighting.
- Run your finger over the crack—if your fingernail catches, it’s likely a deeper crack.
- Shine a flashlight along the crack to assess depth.
Step 2: Check for Leaks
Even small cracks can lead to water loss and long-term damage if they start leaking. To test whether the crack is allowing water to escape, follow this simple dye test.
- Dry the tank completely.
- Add food coloring or dye to the water inside the tank.
- Wait 15-30 minutes—if the dye leaks through the crack, the damage is severe.
Step 3: Determine the Crack Type
Not all cracks can be fixed—some require a full replacement to prevent ongoing leaks and water damage. The key is figuring out whether the crack is small and manageable or big enough to cause leaks.
If your tank has a large crack or keeps leaking, it’s best to replace it now before it leads to water damage or expensive repairs.
Use this table to help decide what to do next.
| Type of Crack | Description | What to Do |
|---|---|---|
| Hairline Crack | Thin, superficial, no leaking | Repair with epoxy or porcelain sealer |
| Severe Crack | Deep, leaks water, multiple cracks | Replace the toilet tank |
How to Fix a Hairline Crack in a Toilet
If your toilet tank has a hairline crack, follow these steps to seal it properly.
Here’s what you need:
- Epoxy or porcelain sealer (designed for ceramic or porcelain repairs)
- Sandpaper or emery cloth (to roughen the surface)
- A clean, dry cloth
- Disposable gloves
- Putty knife (for spreading sealant)
- Caulking gun (for precise application of sealant)
Step 1: Drain and Dry the Tank
For the repair to work, the toilet tank must be completely dry. First, turn off the water supply and flush the toilet to empty the tank. Use towels to absorb any leftover moisture, then let the tank air-dry fully. Even a small amount of water can prevent the epoxy from bonding properly, so ensure the tank dry before proceeding.
Step 2: Sand and Clean the Crack
Next, prepare the surface to help the epoxy stick. Lightly sand the cracked area with emery cloth or sandpaper to create a rough texture, which improves adhesion. Once sanded, wipe the area clean with a dry cloth to remove dust and debris. A smooth, dust-free surface ensures the sealant adheres properly.
Step 3: Apply Epoxy or Sealer
Now it’s time to seal the crack. Wearing gloves, mix the epoxy or porcelain sealer according to the package instructions. While plumber’s putty is useful for setting bath or sink drains, it is not recommended for fixing cracks in toilet tanks. Using a putty knife, spread a generous amount of sealer over the crack, making sure it completely covers the damaged area. Smooth out any excess product and let it cure for at least 24 hours before refilling the tank.
Step 4: Test for Leaks
Once the sealant has fully dried, it’s important to check that the repair holds. Refill the tank with water and watch closely for any signs of leakage. If water seeps through the crack, drain the tank again and apply another layer of epoxy. If leaks persist after multiple repair attempts, the damage may be too severe, and replacing the toilet tank is likely the best option.
With proper sealing and maintenance, a small crack can often be repaired successfully, helping you extend the life of your toilet without the hassle of a full replacement.
When to Replace Your Toilet Tank
If repairs don’t hold or the crack is severe, it’s time for a replacement. If a tank breaks unexpectedly, it can lead to significant water damage in your home. Here are the clear signs that your tank needs to be replaced:
Large Cracks or Multiple Fractures
If your toilet tank has multiple cracks or larger cracks, it is likely beyond repair. Even if only one crack is currently leaking, others may develop over time, leading to water damage and costly repairs.
Leaks Persist Even After Repair Attempts
A properly applied epoxy or porcelain sealer should stop minor leaks. However, if water continues to seep through the cracks, it means the damage is too severe to be fixed. A leaking toilet tank can waste gallons of water per day, increasing your utility bill and causing potential water damage to your bathroom floor.
Cracks Near the Base or Flush Valve
If a crack is located near the base of the tank, flush valve, or bolt holes, it’s much harder to repair. These areas experience constant water pressure and stress, making them prone to worsening over time. Even if sealed temporarily, cracks in these locations often reopen or expand, leading to leaks and possible structural failure.
How to Replace Your Toilet Tank
Step 1: Turn Off the Water Supply and Drain the Tank
Locate the shut-off valve near the base of your toilet and turn it clockwise to stop the water flow. Once the water is off, flush the toilet to empty the tank. If there’s any remaining water, use a towel or sponge to soak it up completely.
Step 2: Disconnect the Water Line and Remove the Bolts
Using an adjustable wrench, unscrew the water supply line where it connects to the bottom of the tank. Then, locate the bolts securing the tank to the toilet bowl and carefully unscrew them. If the bolts are stuck, apply penetrating oil to loosen them.
Step 3: Lift Off the Old Tank and Clean the Area
Once the bolts are removed, carefully lift the old tank off and set it aside. Use a clean cloth to wipe down the area where the new tank will sit, removing any debris, rust, or mineral buildup.
Step 4: Install the New Tank
Place the new tank onto the toilet bowl, ensuring it is properly aligned with the mounting holes. Insert the bolts through the designated openings and hand-tighten them first to keep the tank in place.
Step 5: Secure the Tank and Reconnect the Water Supply
Using a wrench, tighten the bolts evenly—but be careful not to overtighten, as this could crack the porcelain. Once the tank is secure, reconnect the water supply line and slowly turn the shut-off valve back on.
Step 6: Test for Leaks
Let the tank fill with water and check for any leaks around the bolts, base, or water connection. If you notice any leaks, carefully tighten the connections until they are fully sealed.
Once your new toilet tank is installed and working properly, flush the toilet a few times to ensure everything is functioning correctly. If leaks persist, consider consulting a professional plumber for further assistance.
Should You Fix Your Toilet Tank or Replace It?
A cracked toilet tank can waste water and lead to expensive damage if ignored. Repairing cracks can often be done using epoxy or porcelain sealer, but larger or leaking cracks usually require a full replacement to prevent future issues. Acting quickly can help you avoid costly repairs and water damage down the road.
If you’re unsure whether to repair or replace your toilet tank, our team at Stellar Plumbing is here to help. We offer expert toilet repair and replacement services to ensure your bathroom stays leak-free and efficient. Contact us today for professional advice and reliable plumbing solutions!