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How To Replace A Toilet Fill Valve In 15 Minutes 

Note: This post may contain affiliate links. This means that at no cost to you, we may receive a small commission for made purchases.

For whatever the reason, you may find yourself in a situation where you need to replace a toilet fill valve.

You may notice your toilet not flushing properly or the toilet water isn’t running smoothly, these could both be signs that you need to replace your fill valve.

For some, this may sound like a daunting task and your first thought would be to call a professional.

However, while the thought of replacing a fill valve may sound hard, it is, in fact, relatively easy and shouldn’t be too difficult.

To make this even easier for you, we have created a complete guide to help you replace your fill valve in just 15 minutes. So you don’t have to worry about calling a professional. 

What Is A Fill Valve?

If you have never replaced a fill valve before, you may be wondering what it is.

Every time you flush a toilet it releases the water from the tank, a fill valve is then responsible for filling this water backup.

This could be considered one of the most important parts of the toilet tank. 

You will typically find a toilet fill valve located on the left side of a toilet tank, from here you should notice a water line that is connected to the fill valve from underneath the tank. 

From the inside of the toilet tank, this fill valve is connected to the toilet float.

Likewise, it is also connected to the overflow tube through the refill tube.

If you have an older toilet, you may notice a float ball that is connected to the fill valve along with a level.

Meanwhile, modern toilets have a float cup or cylinder that is attached to the fill valves’ vertical body directly. 

The first thing to do when replacing a fill valve is to turn off the water supply.

To do this, flush the toilet then detach the supply line from the tank. Next, take off the locknut, withdraw the refill tube from the overflow valve and then take it out.

Modify the range of the new fill valve, glide it in place and use the locknut to make sure it’s secure.

Reattach it back to the water and fasten the refill tube to the overflow valve. 

How Do I Know My Toilet Valve Needs Replacing? 

Unless you are looking at your toilet tank every single day, it can sometimes be hard to know when your toilet valve needs to be replaced.

Luckily for you, we have compiled a list of some of the most telltale signs that you should replace your toilet valve. These are:

  1. Your toilet is taking too long to refill.
  2. Your toilet won’t stop running water.
  3. When your toilet starts making a humming/ screeching noise.
  4. The toilet has a weak flush/ isn’t flushing at all.
How To Replace A Toilet Fill Valve In 15 Minutes

How Does A Fill Valve Work?

Before you start replacing your toilet valve, first, it’s important to understand how one works.

This will make it easier to replace your toilet valve. Prior to flushing your toilet, your tank should be full of water with the fill valve shut and the flapper should be on the flush valve opening, with the toilet float at the top of the tank.

Below, you will find a detailed account of what happens when you flush your toilet. 

Flush Valve

The toilet flushing handle (see also ‘How To Fix A Loose/Wiggling Toilet Handle Fast!‘) is connected to a chain. When you flush the toilet, you’re lifting up the chain that is attached to the toilet flapper which lifts up and uncovers the opening of the flush valve.

For flushing to happen, the water that is found in the tank flows to the toilet bowl through the flush valve. 

After the flushing handle has been released, the toilet flapper returns back onto the flush valve opening which allows the tank to refill with water. 

Toilet Float 

Following the flush of the toilet, the toilet float moves down to the bottom of the water tank, this opens the fill valve.

When water starts to fill the tank once again, the toilet float moves up gradually with the water.

Once it has reached its set height, it will stop moving and close the fill valve. 

Refill Tube

When looking for the refill tube, you should notice a small tube that is connected from the fill valve to the overflow tube.

Once finished flushing and all the water has returned to the tank from the fill valve, the refill tube will send a small amount of water back to the toilet bowl. 

This is the water you will notice if you look inside your toilet. It also acts as a barrier to prevent any sewer gases or smells from entering your home. 

Water Supply Line 

The water supply line is recognized as a tube that is connected from the shut-off valve to the toilet tank.

Particularly, it is attached to the fill valve and supplies it with water when need be. 

Overflow Tube

The overflow tube acts as the tank’s failsafe and is easily recognizable as the large tube in the toilet tank.

For whatever reason, if the fill valve is defective or not working properly, and water is continually filling the tank, the overflow tube will send this water back to the toilet bowl to prevent overflowing the toilet tank

In such cases, if your water is continually flowing this is typically a sign that the toilet flapper is not sealing properly, or, another reason could be that the fill valve is defective and is continually sending water to the toilet bowl.

How To Replace A Toilet Fill Valve?

Replacing a toilet fill valve is generally an easy task to do and shouldn’t take more than 15 minutes if you have all your materials and new valve already with you.

However, before we start the step-by-step process, below, you will find all the materials you need to complete this. 

How To Replace A Toilet Fill Valve In 15 Minutes

Materials You Need:

  • Sponge – This will help soak up any excess water in the toilet water tank.
  • Adjustable Wrench – To help loosen any tight screws.
  • Measuring Tape – This will be needed to measure your new fill valve, and to make sure everything is in the correct place.
  • Small Bucket – For any leftover water in the water supply line, this will help prevent any unwanted messes.
  • New Fill Valve – This is what you will use to replace your old fill valve.

Step 1: Drain Your Toilet 

The first step is to turn off the water supply to your toilet. To do this, you should notice a shut-off valve located on the wall behind your toilet, turn this clockwise.

There are different types of shut-off valves including pulling/ push types. To shut this off, hold the valve handle and pull it outwards. 

Once this has been completed, flush your toilet and hold down the lever (or button) to remove as much water from the tank as possible.

Next, remove your toilet tank lid, making sure you put it in a safe place for when you replace it. 

Use the sponge to dry up as much water as you can from the bottom of the tank until there is no more water left. 

Step 2: Detach The Old Fill Valve 

To start with, you need to disconnect the water supply line from the toilet tank.

To do this, you can use your hand to loosen the coupling, if this is too tight, use the wrench.

Make sure you have a bucket with you to catch any water that is still left in the supply line.

Next, remove the fill valve lock nut, this holds the valve in place from the underside of the tank.

Again, you can try to use your hands to remove this nut; however, if too tight, use a wrench. 

Next, you are going to want to disconnect the refill tube from the overflow tube and hoist off the fill valve.

You can take this time to clean your tank if need be, especially the area where your new fill valve is going to be set. 

Step 3: Fit You New Fill Valve

Take your new fill valve and inspect its gasket to make sure everything looks ok.

You should notice that this gasket seals the opening where the valve is fitted, this is to prevent any water from leaking out the bottom of the tank. 

Place your fill valve in the right position within your toilet tank; however, don’t tighten any screws just yet.

Next, take out your measuring tape, with your measuring tape you are going to want to measure the distance between the top cap of the valve and the top of the overflow tube. This should be a distance of 3 inches. 

Take out the fill valve and adjust the height if need be. To do this, hold the valve body in one hand while using your other hand to turn the threaded shank clockwise or counterclockwise until you have reached your desired height. 

How To Replace A Toilet Fill Valve In 15 Minutes

Once the height is properly adjusted, put the fill tank back into the desired position.

From underneath the tank, screw in the locknut to ensure that the valve is firmly secured in place.

Reconnect the water supply back to the new fill valve by hand tightening any screws, do not use a wrench. 

Fasten the refill tube to the overflow tube. If you notice that the refill tube is too long, you can go ahead and cut it into a size that fits properly.

This will prevent the refill tube from siphoning water from the toilet bowl.  

Step 4: Reconnect The Water Supply

To start with, all you have to do is open the shut-off valve to allow water to refill the water tank.

When doing this, make sure to check the new fill valve to make sure that it is filling the tank faster, and quieter, and that the water level inside the tank is about half an inch below the overflow tube.

Also, make sure that no water is running from the tank back to the bowl. 

You can check if everything is running smoothly by flushing the toilet a couple of times.

If everything looks good and you’re happy with the installation, you can go ahead and replace the lid on the toilet.

Congratulations, you have successfully replaced your very own toilet fill valve! 

Final Thoughts

While the thought of replacing a toilet fill valve sounds like a lot of work, it is a relatively easy task, you don’t even have to be a professional!

Hopefully, this guide has informed you of all the different details about a toilet valve replacement and provided a clear step-by-step process to do so.

author avatar
Anthony Barnes
Anthony Barnes is the founder of Water Heater Hub and a second-generation plumber by profession. Before developing Water Heater Hub, Anthony Barnes was a full-time plumber, and he has undertaken a wide variety of projects over the decades. As a second-generation plumber, it was easy for Anthony to get used to the technicalities of all from a tender age


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