How To Replace a Toilet Fill Valve

White toilet in home
ben-bryant / Getty Images
  • Total Time: 15 mins
  • Skill Level: Beginner
  • Estimated Cost: $8

The fill valve is the device that controls the flow of fresh water into the tank of your toilet. It is normally mounted on the left side of the toilet tank, with a tailpiece that extends through the bottom of the tank, where it attaches to a supply tube that runs to a fixture shutoff valve. This part is sometimes known as a ballcock, so named after a design that was once the standard. 

The toilet fill valve opens and closes every time the toilet flushes. Over time, the valve simply wears out and must be replaced. If the existing fill valve is an older model with a float ball, now is your chance to replace it with a more modern and dependable fill valve with its own integrated float cup.

You might also consider using this opportunity to also replace the flush valve assembly. These parts also go bad eventually, and if you want to do a maintenance upgrade, you can buy a kit that includes both the fill valve and flush valve assemblies. Be aware, though, that if you go this route, it will require you to temporarily remove the entire tank. 

The project shown here involves replacing only the fill valve, a relatively easy job that can be done with the toilet tank in place. 

What You'll Need

Equipment / Tools

  • Sponge and bucket
  • 2 channel-type pliers
  • Scissors (as needed)


  • Toilet fill valve


  1. Turn Off the Water and Empty the Tank

    Turn off the water to the toilet by turning the handle of the fixture shutoff valve clockwise until it stops turning. Normally, the fill valve is located on a water supply pipe coming out of the floor or wall near the bottom left side of the toilet tank, near where the water supply tube connects to the tailpiece on the fill valve. 

    Flush the toilet to empty the tank, then remove the cover on the tank and use a sponge to mop up any remaining water in the bottom of the tank.

    Water shutoff valve and hand
    PictureLake / Getty Images
  2. Remove the Toilet Fill Valve

    To remove the toilet fill valve, first disconnect the water supply tube attached to the bottom of the fill valve tailpiece, using channel-type pliers or an adjustable wrench.

    Next, loosen and remove the mounting nut that holds the bottom flange on the fill valve to the bottom surface of the tank. You may need to reach down into the tank from the top and grip the bottom of the fill valve with another set of pliers to keep it from rotating as you loosen the mounting nut. 

    Removing the toilet fill valve. Aaron Stickley
  3. Prepare the New Fill Valve

    Slide the rubber washer included with the kit onto the bottom flange on the fill valve tailpiece. This washer will provide an inner seal that prevents leaking around the base of the fill valve.

    Adjust the height of the fill valve, if necessary. Different valves have different methods of doing this, but with most, it's a simple matter of screwing the stem piece shorter or longer so the overall length of the fill valve will fit inside your toilet tank. Ideally, the top of the fill valve should be slightly taller than the top of the overflow tube, but not so tall that it will prevent the tank lid from closing.

    Preparing the new fill valve. Aaron Stickley
  4. Install the New Fill Valve

    Set the fill valve into the toilet tank, inserting the tailpiece through the opening in the bottom of the tank. Position the valve so the water outlet nipple is facing the overflow tube in the tank.

    Holding the fill valve with one hand, use the other hand to thread the mounting nut onto the tailpiece from below the toilet. Tighten the mounting nut so it is hand-tight. Use channel-type pliers to tighten the mounting nut slightly further. Make sure not to twist the body of the fill valve inside the tank.

    Reconnect the water supply tube to the fill valve. Once again, you can hand. Once again, hand-tighten first and then use pliers to tighten a little more.

    Installing the new fill valve. Aaron Stickley
  5. Connect and Make Adjustments to the Fill Valve

    Attach one end of the rubber fill tubing to the nipple on the top of the fill valve, then attach the plastic or metal adapter onto the other end of the tubing and clip it to the top of the overflow tube.

    You may need to cut the rubber tubing with scissors if it's too long. It should make a smooth bend (with no kinks) when connected to the overflow tube.

    Turn on the water supply valve all the way, and watch as the toilet tank refills with water. Adjust the water level to a height that is appropriate for your toilet, following the valve manufacturer's instructions. The tank should fill to a marked water line on the inner walls of the tank; the water level should be about 1 inch below the top of the overflow tube.

    Inspect the fittings on the bottom of the tailpiece and shutoff valve to make sure there are no leaks. You may need to tighten them slightly more if there is any seepage. 

    Connecting the new toilet fill valve. Aaron Stickley