If you have a toilet leaking between the tank and bowl, it is likely that the seal between the two has failed or the tank got damaged.
Either way, this guide will show you how to stop the leak at home without consulting any professional plumber.
Determine the Cause of the Toilet Leak
You may not be able to apply a permanent fix based on presumption. You need to identify the reason behind the leak to be able to apply the right fix.
The common causes of the issue include-
- Worn-out shank gasket (also known as spud washer or tank-to-bowl gasket)
- Cracks under the toilet tank
- Loose tank bolts and nuts
How to Fix a Toilet that’s Leaking Between Tank and Bowl?
Based on the reason that may have caused the issue in your toilet, you can apply these solutions for a permanent fix-
- Tightening the loose tank bolts and nuts
- Replacing worn-out toilet tank-to-bowl gasket and parts
- Replacing the toilet tank with a new one
Now, let’s go into more detail on how to apply these fixes.
1. Tightening Loose Bolts and Nuts
Here is the step-by-step guide to tightening the loose nuts and bolts without damaging the toilet-
Step 1: Shut Off the Water Supply
You need an empty toilet tank to apply any of these fixes. The first thing to do is to shut off the water supply to prevent the tank from refilling after flushing.
Look behind the toilet bowl, you should see the shut-off valve. Your toilet may have a push/pull valve, a faucet, or a tap. The shut-off valve is usually connected to a supply line that connects to the fill valve.
Turn the shut-off valve completely in a clockwise direction to shut off the water supply. Pull the push/pull valve to shut off the water supply.
Step 2: Flush the Toilet
Remove the tank lid and place it in a safe place. Press and hold down the handle lever (or flush button) on your toilet tank to flush and empty the tank.
If you still have some water remaining in the tank, mop this off with a sponge or towel.
Otherwise, you will end up spilling water on your toilet floor and on your body.
Step 3: Check and Fix Loose Nuts
Before going further, check whether the cause of the toilet leak between the tank and bowl is loose nuts. This will save you a whole lot of time and effort.
Using a wrench, carefully check if any or all of the nuts located under the toilet bowl feel loose.
If yes, loose nuts are probably the culprit. Simply tighten the bolt to firmly secure the tank and stop the leak. Replace the bolts, nuts, and washers if they are rusted.
Open the water supply, flush your toilet, and check if the leaking stops or continues.
If there is no more leaking, the problem is fixed. If the leaking is reduced, try to tighten the nuts further.
If the leaking continues, proceed with the next solution.
2. Replacing Worn-out Shank Gasket
In case the bolts are snug but the leak is still present, a damaged shank gasket may have been causing the issue.
Once you confirm that bolts and nuts is not the problem, move on with the following steps to fix other causes.
Step 1: Shut Off the Water Supply and Flush the Toilet
Simply shut off the water supply and flush the toilet as explained in steps 1 and 2 above.
Step 2: Disconnect the Water Supply Line
Fixing worn-out tank-to-bowl gasket and parts or replacing the tank requires you to remove the tank.
To remove the tank, you need to disconnect the water supply line to avoid damaging any plumbing fixture.
Using your hand, gently unscrew the rubber hose from the bottom of the tank. If unscrewing the hose with your hand seems difficult, use a wrench to gently loosen it.
Don’t forget to place a bucket beneath the hose to catch the excess water from the hose.
Step 3: Disconnect the Tank from the Bowl
The next step is to disconnect the tank from the bowl to enable you to access the tank-to-bowl gasket and other hidden parts.
The toilet tank connects with the toilet bowl using the tank-to-bowl sponge gasket.
To prevent shifting, the tank and bowl are held together tightly using tank bolts and nuts.
Depending on the toilet model, these bolts can be two or three, placed around the flush valve drain.
With a flathead screwdriver, unscrew the bolts from inside the tank. If unscrewing the bolts seems difficult, use a wrench to loosen the nuts from under the toilet bowl.
Sometimes, both the bolts and nuts may turn together because of rust and won’t come out. Hold down the nut with a wrench and loosen the bolt with a flathead screwdriver. You may need to apply some effort here.
If the bolts and nuts won’t still come off due to excess rust, you can apply penetrating oil to them. Otherwise, cut them off with a hacksaw blade.
If this is exactly what you encounter, you need to get replacement bolts, nuts, and washers of the same length to replace the old ones.
Step 4: Remove the Tank
With the bolts removed, it’s time to remove the tank.
Gently grab the tank at the bottom with both hands and lift it up straight carefully. If you aren’t careful enough, you may end up damaging the flush valve inside the tank.
Lay the tank gently on its back on a flat surface. Make sure that the place is safe to avoid damage.
Lay an old carpet or cushioning before you place the tank for added safety.
Step 5: Remove the Damaged Tank-To-Bowl Sponge Gasket and Parts
Now, you have easy access to the tank-to-bowl sponge gasket and other hidden parts.
Check if the spud washer is bad or worn out. If the spud washer is bad, get a replacement for it.
Otherwise, you need to change the entire tank-to-bowl gasket unit.
Using a wrench, unscrew the compression nut by turning it anticlockwise – you may try using your hand first.
Once the compression nut is out, gently slide out the tank-to-bowl gasket.
Take this to a store and buy the same replacement model. Make sure that the old and new components match each other.
Also, purchase a new O-ring gasket.
If the old bolts and nuts are worn-out, purchase a new tank-to-bowl bolt kit also.
We recommend that you buy a new tank-to-bowl bolt kit even if the old bolts and nuts look fine. This will enable you to achieve a better leak-proof result.
Step 6: Reattach the New Tank-To-Bowl Sponge Gasket and Parts
Take your time to carefully clean around the hole. Check if there are debris or mineral deposits, take them out using a brush before installing the new parts.
Sometimes, remains from the old gasket may stick to either side of the tank. Carefully clean the inner and outer surface for the new tank-to-bowl gasket to properly seat and seal.
Gently insert the new component from inside the tank. Carefully arrange the washers (metallic and rubber) – the rubber washers are the ones in contact with the tank.
They prevent cracking by absorbing the shocks from the over-tightening of the nuts.
Secure the gasket with the compression nut from under the tank. The compression nut squeezes everything together to ensure a leak-proof seal. You can use a wrench to tighten them together.
Cover the outer end with the spud washer. Also, make sure that the new tank-to-bowl seal fits perfectly to the flapper valve nut in the tank.
Step 7: Set the Tank onto the Bowl
Carefully place the tank on the bowl, ensuring that it sits well in the right direction above the bolts’ holes.
Don’t forget to place the spud washer (or sponge rubber gasket) before setting the tank onto the bowl for stability.
Place the washers on the bolts and insert the bolts from the inside of the tank.
Place each nut on its bolt under the bowl and screw the nut tightly using your hand.
Tighten the bolts and nuts together using a wrench and/or screwdriver.
Ensure that the tank is stable and sits secured on the toilet bowl. Nevertheless, don’t over-tighten the nuts to avoid cracking the porcelain toilet bowl.
Step 8: Test the Toilet
Before reattaching the water supply line, it is important to test the toilet to check if everything is fixed.
Pour some water into the tank and check for leaks.
If your toilet runs, the flapper has possibly shifted position during the fix, adjust the flapper to fix it.
If there is no leak, then you have successfully fixed your leaking toilet.
Step 9: Reconnect the Water Supply Line and Flush the Toilet
Using your hand, tightly screw the rubber hose to the bottom of the tank. Make sure that the screw is tight to avoid leaking or low pressure.
Turn on the shut-off valve by turning it anticlockwise and let the tank fill with water. A push/pull valve requires that you push it inwards to open it.
Inspect the tank and bowl for a few minutes, looking out for any leaks between them.
If you don’t see any leaks, flush the toilet and look out for any leaks again. If no leaks, then everything is perfectly fixed.
Place the lid on the tank and tidy up your toilet and work area.
3. Replacing the Toilet Tank with a New One
However, if your toilet still leaks due to a cracked tank, the best solution is to get a replacement tank. Make sure that the new toilet tank is of the same model as the old one.
Carefully follow step 7 above on how to install the new toilet tank. Repeat steps 8 and 9 above to ensure that everything is fixed.
For a better understanding of how to fix a toilet leak between the tank and bowl, here is an instructional video to guide you –
I hope this article has given you some insights on how to fix a toilet leaking between the tank and bowl.
If you have any questions or suggestions, please feel free to leave a comment below. I would be happy to hear from you.