Replacing a Toilet Fill Valve

There comes a time in the life of almost every toilet when the fill valve has to be replaced. The fill valve is the mechanism inside the toilet tank that controls refilling the tank after each flush.

Often, a fill valve goes bad because of the build-up of mineral deposits from the water that begins to interfere with the opening and closing of the valve, leading to a toilet that’s constantly running.

Fill valves are inexpensive enough and not that complicated to install. Doing it yourself can save the cost of a plumber who may charge $60 an hour or more, or an even higher fixed-rate price for a job that should take less than 30 minutes.

When you buy a replacement fill valve, it will include detailed installation instructions, which are not reproduced in this article. Instead, this article looks at different types of fill valves and describes the basic steps so you’ll have the confidence to do it yourself.

I have covered other common toilet repair problems here.

Valve Types

All fill valves work similarly, and the two most common types differ only in the type of float used. One has a cylindrical float that moves up and down a shaft, while the other has a plastic ball the size of a softball on the end of a long metal rod.

Neither has a particular advantage over the other, except the cylindrical-float type is more compact. If you have the ball type, you can replace it with either model. If you have the cylindrical type, you should probably replace it with a similar model since the tank may not have adequate space for the bulkier ball type.

Basic Steps for Removing the Old Valve

  1. First, turn off the water supply to the toilet using the valve handle on the floor or wall behind your toilet. Then flush the toilet to drain the water from the tank. You’ll probably also need a sponge and a bucket to sop up the little bit of remaining water out of the tank so it doesn’t leak onto your floor when you remove the old fill valve.
  2. Next, disconnect one end of the hose running from the wall or floor to your tank (Disconnect it at the tank end.) Usually, you can loosen the plastic connecting nut on the underside of the tank by hand, but you may need a pair of pliers or crescent wrench if it’s been overly tightened.
  3. With that end of the hose disconnected, now use a wrench in the same location under the tank to loosen the retaining nut that holds the fill valve in place.
  4. Inside the tank, you’ll find a plastic hose running from the valve and clipped onto the edge of the overflow tube. Unclip this from the overflow, and you should be able to lift the old valve out of the tank. This should have taken you about ten minutes and you’re now halfway done with the job.

Basic Steps for Installing the New Valve

Your replacement valve will have detailed installation instructions, usually illustrated. Basically, you’re going to follow the same steps you took for removal, but in reverse.

  1. Insert the new fill valve in the hole where you removed the old one. Pay attention to properly installing the rubber washers that are needed to prevent leakage around the hole. Attach and tighten the retaining nut on the underside of the tank. Be careful not to over tighten so much that it cracks your tank or you will need to replace your tank.
  2. Next, reattach the hose from your water supply to the new fill valve. Again, pay attention to any washers needed to prevent leaks. Inside the tank, connect the plastic hose from the fill valve to the overflow tube as described in your instructions.
  3. Turn the toilet supply valve back on and check for any drips where the hose connects to the tank. If you have leaks, turn off the water, and re-tighten your connections. (Sometimes using plumber’s “pipe dope” can help you solve an obstinate leak problem.)
  4. With the water supply turned on, watch as your tank fills. The float should shut off the water when the water level is about ¼ inch below the top of the overflow tube. If the water level is too high or too low, adjust the float accordingly.

There! You’re done in about 20 minutes. If you saved $60 with 20 minutes worth of work, you just made $180 an hour!