[DIY] How to Replace Toilet Flush Valve Seal?

A flush valve seal is not difficult to replace even if you have no prior plumbing skills. Simply follow these simple steps to get the job done efficiently and effectively.

These steps work for any toilet brand or flush mechanism as long as you’re using the right flush valve seal.

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So, without any further ado, let’s get started!

Step 1: Get the Perfect Flush Valve Seal

First, make sure that the new flush valve seal you’re purchasing is the right one for your toilet model. You should find the toilet model name or number on the body of the toilet tank. Sometimes, it’s written inside the tank but near the top.

The seal may not be from the maker of your toilet – that’s not necessary. What’s important is the new flush valve seal must fit your toilet.

If you’ve previously changed the flush mechanism of your toilet, get the appropriate flush valve seal for the flush mechanism.

Step 2: Shut the Water Valve

Before you empty the toilet tank, make sure that you stop the water supply to the toilet tank. Otherwise, the toilet tank will get refilled.

Find the water valve and shut it off by turning it in a clockwise direction. If you use the push/pull valve, pull it to shut the water.

The water valve is usually located behind the toilet bowl on the left side. Sometimes, it is situated under the toilet tank.

Whichever way, it connects to the rubber hose or pipe that channels water into the tank.

Step 3: Remove Water from the Toilet Tank

Press and hold down the flush lever to empty the toilet tank. Then disconnect the flapper lift chain from the flush lever.

A leaking toilet is the main sign of a faulty toilet valve seal. However, depending on your flush mechanism, another sign is difficulty in pressing down the flush lever. If this applies to you, you may not be able to press down the flush lever to flush your toilet.

In that case, remove the lid from your toilet tank. Locate the flush valve assembly in the tank and lift the flush valve float gently to drain the water.

Use a sponge to remove any remaining water from the toilet tank.

Step 4: Disconnect the Toilet Tank

Depending on your toilet model and flush mechanism, you may need to disconnect the toilet tank from the bowl.

Foremost, disconnect the water supply line from the fill valve under the tank by turning the connector anticlockwise. Next, from inside the tank, unscrew the two (or three) tank bolts securing the toilet tank to the bowl.

Sometimes, you may need to cut the tank bolts, especially if they’re rusted or worn out and won’t come out.

Lift the toilet tank carefully off the bowl and keep it on its side somewhere safe. If your toilet uses a flush valve float, skip this step.

Step 5: Disconnect the Flush Valve Cartridge

Disconnect the refill tube from the overflow tube by unclipping it. Remove the tank-to-bowl gasket and unscrew the compression nut to disconnect the flush valve cartridge. Pull out the entire cartridge from inside the tank.

Underneath the assembly just above the threading, you would see the flush valve seal. If your toilet uses a flush valve float, unscrew the refill tube and lift the float gently to remove it. Disconnect the trip lever as you pull out the flush valve float. The flush valve seal is now exposed.

Step 6: Remove the Faulty Seal

The flush valve seal comes in different colors, such as red, blue, or black. Use your fingers to gently grip the edge of the faulty seal and pull it off the flush valve.

Remove the new seal from the pack and work it into the flush valve’s body. Make sure that it fits firmly around the perimeter of the flush valve.

Insert the flush valve assembly back into the toilet tank and tighten the compression nut firmly – don’t over-tighten.

For toilets with a flush valve float, simply return the flush valve float as you send the trip lever back through it.

Next, tighten the refill tube.

However, if your toilet has the traditional flush assembly, move to the next step.

Step 7: Replace the Toilet Tank

Some replacement seal kits also come with a new tank-to-bowl gasket, flapper, washers, and tank bolts. If necessary, replace the tank-to-bowl gasket and flapper with the new one before replacing the toilet tank.

Also, fit the tank bolts and first set of nuts under the toilet tank.

Carefully set the tank on the bowl, so that the bolts go directly into their corresponding holes on the bowl.

Insert the washers and tighten the nuts onto the bolts using your hand. Tighten the nuts further using a wrench but don’t overtighten.

Connect the flapper lift chain to the flush lever and close the tank lid.  

Step 8: Reconnect the Water Supply and Test the Flush Function

Now reconnect the water line, turn on the water valve, and allow the toilet tank to refill. Leave for some minutes as you listen carefully for any leaking sound.

Also, look around and check for any leaks around the base.

Any sign of leaks means either the seal is not properly fitted or connections are not well tightened.

Make all necessary readjustments. Press the flush lever to test its function.

The flush lever should be very easy to press now. If everything works fine, replace the tank lid and your toilet is now ready for use.


Replacing a faulty flush valve seal in your toilet tank is an easy DIY project that you can do yourself with the right tools and instructions.

We’ve outlined the steps for you here, so follow them closely to get the job done without any trouble.

If you experience any problems along the way, be sure to consult our troubleshooting guide.

Finally, once you’ve replaced the faulty seal, test the flush lever to ensure that it works properly – there should be no resistance at all when you press it down.

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