How to Fix a Toilet Flush Valve: An Easy Step-By-Step Guide

Updated on April 4, 2019
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Xixi has been an online writer for over eight years. Her articles focus on everything from home repair to romance.

If you hear your toilet running constantly, chances are you have a leaking flush valve. This is the most common problem in a toilet tank setup and is fairly easy to fix. Fixing it yourself can save a lot of money in water usage, and you won't have to hire a professional plumber.

Parts of a Toilet

  • Flush valve: The mechanism inside the toilet tank that regulates the refilling of the tank after each flush. It connects to a water source through a hose or a small pipe that attaches to the bottom of the toilet tank.
  • Ball float: The plastic ball that regulates water level.
  • Flapper: The flat circle that seals the flush valve seat.
  • Flush valve seat: The hole at the bottom of the tank.
  • Flush lever: The handle that connects to the lift rod from the outside.
  • Overflow pipe: The vertical pipe in the centre of the tank.
  • Refill valve: The ballcock.

Click thumbnail to view full-size
Flapper moves up and down the cylindrical shaft.The soft ball-like float regulates the water level.
Flapper moves up and down the cylindrical shaft.
Flapper moves up and down the cylindrical shaft.
The soft ball-like float regulates the water level.
The soft ball-like float regulates the water level.

Types of Toilet Tank Setups and Reasons They May Leak

There are two common types of flush valves in toilet tanks. The modern ones have a cylindrical float that moves up and down a shaft in a vertical fashion, while the older models have a tank ball float at the end of a long metal rod. Much like the cylindrical float, the ball float rises and falls with the water level in the tank. When the flush lever is pulled, it lifts the flapper, allowing the water in the tank to flush down into the toilet bowl. The cylindrical float or ball float then raises with the water level, shutting off the water supply once the correct level is reached.

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

  • The flush valve is damaged.
  • The flush valve doesn't seal tightly because of built-up mineral deposits.
  • The flapper is worn out.

To confirm a leak, simply turn off the tank's water supply, mark the water level, and wait about 30 minutes. Iif the water level has dropped, you have a leaking valve.

A small leak may seem unimportant, but if ignored, it will raise your utility bills and could even damage your flooring. It only costs about $8–$10 to fix it yourself, so follow the steps below before calling a plumber.

Click thumbnail to view full-size
Worn out or damaged valve.Taking out the worn out flapper.
Worn out or damaged valve.
Worn out or damaged valve.
Taking out the worn out flapper.
Taking out the worn out flapper.

How to Install a New Flush Valve

If you've established that the cause of the leak is a damaged flush valve, you have to buy a new one. Take the damaged one to the store with you to make sure you are replacing it with the same model. Also, make sure that the new one has a vacuum breaker to prevent your water supply from being contaminated.

You'll need:

  • A wrench
  • A flat-blade screwdriver
  • A dry towel

To fix a one-piece flush valve that has the float and flapper integrated into the valve assembly, follow these steps:

Step 1: Turn off the Water Supply

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

Shut off the water supply.
Shut off the water supply.

Step 2: Flush and Get Rid of Excess Water

Flush what is left in the toilet bowl. Because the water supply is turned off, it should not refill again. Use a dry towel or sponge to suck up whatever water is left.

Step 3: Unscrew the Flush Valve

Unscrew the two rubber bolts by the sides of the flush valve using a screwdriver. Hold the nuts beneath the bowl with a wrench as you unscrew the bolts. Note: Do not force the bolts as it may cause the tank to crack or even break.

Unscrew the flush valve.
Unscrew the flush valve.

Step 4: Replace the Flush Valve

Take out the old flush valve and insert the new one into the tank opening so that the overflow pipe is facing the flush valve. Once you have it in place, hold the valve and tighten the screws using a wrench.

Step 5: Reconnect the Water Supply and Check for Leaks

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

What to Do If Your Tank Has a Ball Float

Follow steps one and two above, then do the following:

  • Remove the ball float using a plastic snap.
  • Unscrew the nut or snap the rod out of the valve.
  • 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 overtighten it.

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

Other Causes of a Leaky Toilet

Worn-Out Flapper

The flapper needs to be replaced if it looks warped or otherwise worn out. This is a super simple fix.

  • 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 back on the handle arm.

Blockage in the Flush Valve Seat

If the flapper is in good condition and the tank is still leaking, the flapper may not be sealing against the flush valve seat due to mineral deposits.

  • Check for mineral deposits on the flush valve seat.
  • Clean the flush valve seat with an abrasive sponge. Don’t use anything that might roughen or scratch the surface, you just want to remove the built-up deposits.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.


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    • profile image


      5 months ago

      This Helped

    • tmbridgeland profile image


      8 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 imageAUTHOR


      9 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


      9 years ago

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

    • katiem2 profile image

      Katie McMurray 

      9 years ago from Westerville

      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 imageAUTHOR


      9 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


      9 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!


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