How to Fix a Leaky Flush Valve

Written by alan edwards
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How to Fix a Leaky Flush Valve
A toilet may flush on its own if it has a leaky valve. (bathroom with patterned green wallpaper image by nextrecord from

You are just drifting off to sleep, and suddenly you hear the toilet flush. Hmmm ... ghosts, a break-in to use your bathroom? No, you most likely have a leaky flush valve. Not to worry -- this is a simple home repair job that will not require a plumber. Go back to sleep and make the repair tomorrow. There are several causes of flush valve leaking. Two require simple adjustments and two involve replacement parts. All are simple to do.

Skill level:

Things you need

  • Replacement flush valve, or
  • Replacement float ball

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  1. 1

    Flush the toilet with the top of the tank open. Check to see whether the flapper valve tightly seals itself on the outflow outlet. If the flapper seats, but the toilet is still running, try lengthening the chain a bit by moving the clip on the chain that is attached to the toilet handle. Move it one or two spots to the right on the part of the handle in the water tank. Reflush the toilet. If no water is getting past the flapper, then you have fixed the problem.

  2. 2

    Bend the float rod that connects to the float ball, which may not be moving the rod high enough to shut off the toilet. Carefully bend the rod up to heighten the float ball's position. The water level in the tank should not be more than 3/4 inch below the top of the overflow tube. (The overflow tube is a clear or white plastic tube that comes straight up).

  3. 3

    Turn off the water supply and reflush the toilet to empty the water tank. Remove and replace the float ball if it has water in it. The cause of your running toilet is that the ball is too heavy to float to the level needed to shut off the water supply. Detach your float ball and take it to the hardware store to get a matching replacement. (You might want to take the flapper valve, too, as it may need replacement. If you do not use it you may return it with a receipt.)

    Install the new float valve following the manufacturer's directions on the packaging or an insert. Turn the water supply back on. Flush. If the leaking stopped, you have successfully repaired the problem.

  4. 4

    Turn off the water supply. Flush the toilet to empty the water tank. Remove the flapper valve and take it to the hardware store to get a replacement. There are many flappers, so this will save you a second trip to the hardware store. Clean the valve seat with an abrasive cleaner or sandpaper to remove any dirt and sediment. Carefully follow manufacturer's replacement directions that come with your new flapper. (Note: Some toilets have a ball instead of a flapper, but the procedures are the same.) Turn the water supply back on. Wait until the tank fills, and flush.

Tips and warnings

  • Always turn off the water supply when working on a leaky flush valve.

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