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How to fix a toilet flush valve: An easy step-by-step guide

Updated on October 12, 2010
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Parts of the toilet tankDiagram showing the different parts
Parts of the toilet tank
Parts of the toilet tank
Diagram showing the different parts
Diagram showing the different parts

A flush valve, also known as the fill valve, is the most likely to become problematic in your toilet tank setup. If you hear your toilet running constantly, then you may be losing water through a leaking flush valve and fixing it yourself can be the best money saving act you will carry out.

The flush valve is that mechanism inside thetoilet tank that regulates the refill of the tank after each flush. It connects to a water source from the bottom of the toilet tank through a hose or a small pipe.

Other parts found in the toilet tank are a tank ball/float or flapper, Flush valve seat (the hole at the bottom of the tank), flush lever (handle connecting to the lift rod from the outside),overflow pipe(vertical pipe in centre of tank) and refill valve(ballcock)

Flapper- moves up and down cylindrical shaft
Flapper- moves up and down cylindrical shaft
Float (soft ball-like)
Float (soft ball-like)

There are two different types of flush valve being used for toilet tanks, the modern ones  have a cylindrical float that moves up and down its shaft in a vertical fashion while the Older models have a tank ball/float (like a plastic ball) at the end of a long metal rod(Flush lever), it raises and lowers with the water level in the tank allowing the flush valve to open and close when the flush lever is pulled.

When there is a leak from your toilet tank, it could be any of the following reasons.

  • a damaged flush valve
  • there could be some mineral deposit from the water blocking the discharge hole(where the flush valve sits)
  • the flapper is worn out

You can confirm a leak, by turning off the water supply into the tank, mark water level and if you return after about 30 minutes and the level has dropped, then you have a leaking valve.

A leak can really mess up your floor tiling and as little as this problem may be, it can cost between $8- $10 to get it fixed and if not repaired immediately can cost much more in your utility bills.

Worn out or damaged valve
Worn out or damaged valve

If you have established that the cause of the leak is as a result of a damaged flush valve, you can repair the old one, replace the old flush ball with a flapper(if your toilet tank has the old model set up as shown above) or get a new one, they are cheap and easy to install.

How to fix a new flush valve

A damaged flush valve means you have to buy a new one. When buying, take the damaged one with you to the store to make sure you are replacing with the same model and that the new one has a vacuum breaker to prevent your water supply from being contaminated.

What you need: A wrench, a straight blade screwdriver and a dry towel.

To fix a one piece flush valve that have the float/flapper integrated into the valve assembly. Follow these steps:

Shut off the supply of water
Shut off the supply of water

Step 1

Turn of the water supply to the tank completely, depending on how it is set up, it can be found on the wall behind the toilet or a small metal pipe by the side of the tank leading into the floor. Use an adjustable wrench to turn knob clockwise till the water stops running inside the tank.

Step 2

Flush out what is left in the toilet bowl (because you have turned off the water supply it should not refill again),use a dry towel or sponge to suck up whatever water is left.

Unscrew flush valve
Unscrew flush valve

Step 3

Unscrew the two rubber bolts by the sides of the flush valve using a screwdriver if need be. These bolts go through the tank and bowl with nuts beneath. Do not force the bolts as it may cause the tank to crack or even break.

Step 4

Take out the old flush valve and Insert the new one into the tank opening so that the overflow pipe faces the flush valve. Once you have put it in, hold valve in place and tighten the screw using a wrench then adjust to control the water level in the tank.

Step 5

Finally, reconnect and turn on the water supply. The tank should fill, allowing you to adjust the water level. Flush and check for leaks and tighten any nuts if necessary

If your tank has the ball float, follow steps 1 & 2 and remove the ball float using a plastic snap. Unscrew the nut or snap the rod out of the valve then put the flush valve through the hole in the bottom of the tank. Hold the flush valve in place with a nylon nut. The nut should be snug, but be careful not to over tighten it

Other causes of toilet leak can be easily fixed

Clean valve seat with an abrasive pad
Clean valve seat with an abrasive pad

Blockage in flush valve seat

Check for mineral deposits, then clean the flush valve seat with an abrasive sponge. Don’t use anything that might roughen or scratch it.

Taking out worn out flapper
Taking out worn out flapper

Worn out flapper

Remove the old or worn out flapper from the overflow tube and detach the chain from the handle arm. Attach the new flapper to the overflow tube and hook the chain to the handle arm


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    • tmbridgeland profile image

      tmbridgeland 5 years ago from Small Town, Illinois

      Thanks. Good Hub. Guess what my weekend chore is today. I have the parts and the tools, but that toilet is so old that the nuts are corroded and frozen to the bolts. Might have to take the whole thing out side, bowl tank and all and cut them off!

    • xixi12 profile image

      xixi12 6 years ago from Everywhere but here. In the truest sense, freedom cannot be bestowed; it must be achieved. You can never be truly free till you have the discipline to manage it.

      Glad you found it informative Whitton, thanks for stopping by

    • whitton profile image

      whitton 6 years ago

      Very informative Hub. These are great instructions on how to fix a toilet flush valve.

    • katiem2 profile image

      katiem2 7 years ago from I'm outta here

      WOW now this is great and will save us all a ton of money. You've made a practical repair easy and doable. Your How to fix a toilet flush valve: An easy step-by-step guide is much appreciated. Thanks!

    • xixi12 profile image

      xixi12 7 years ago from Everywhere but here. In the truest sense, freedom cannot be bestowed; it must be achieved. You can never be truly free till you have the discipline to manage it.

      Thanks for stopping by. Yes it really comes in handy. instead of paying a fortune to the so called professionals for something so little

    • BkCreative profile image

      BkCreative 7 years ago from Brooklyn, New York City

      Real good info here. My daughter's water bill was a fortune one month - I came over and found one of her toilets was running - I changed the flapper.

      What a waste of water this was. I kind of feel - it we are going to have toilets - we should know basic care. I'll send this to my daughter.

      Thanks a lot and rated up!