Toilet Fill Valve: All You Need To Know…

Beginner Info, Toilet

Toilet Fill Valve
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In this post, I’ll walk you through various aspects of a toilet fill valve in order to help you make an informed purchase decision.

Moreover, I’ll also respond to the queries related to toilet fill valves to help you clear your doubts.

So, without any further ado, let’s begin…

The toilet fill valve is an important component of a gravity flush toilet.

A toilet fill valve has an important role to play in regulating the water flow into the holding tank.

The main function of a toilet fill valve is to open the water flow as the flush cycle empties the tank as well as close the water flow once the tank has been to the desired or appropriate level.

In simple words, a toilet fill valve regulates the flow of water into the toilet tank after the flush.

The main types are the plunger (piston) ballcock, diaphragm-type ballcock (brass and plastic body types), float cup, and floatless fill valves. They differ by model, type, noise level, material, and flush rate.

Before making a purchase decision, make sure you’re well aware of different types of toilet fill valves as well as the problems associated with them.

Though it’s a small part of your bathroom setup still you can’t even dare to ignore its significance.

A faulty toilet fill valve can lead to unprecedented situations that I think nobody would want to get into.

Quietest Toilet Fill Valve | IzzySmartHomeGuide.Com Editor’s Recommendation

We at have been recommending the below-mentioned toilet fill valves to our clients and the feedback that we’ve received so far is encouraging and promising.

I hope our readers will also get benefited from these quietest toilet fill valves.

In case of doubts and queries, feel free to reach out to us and our core team will be more than happy to assist you.

Fluidmaster Toilet Fill Valve and Flapper Repair Kit

We’ve been recommending the Fluidmaster Toilet Fill Valve and Flapper Repair Kit to our clients who have been looking for a fix for their noisy and running toilets.

The Fluidmaster is equipped with an idiosyncratic 400A toilet fill valve which is considered to be one of the most popular valves in the world.

What I really adore about this valve is that it consists of an anti-siphon design which is known to prevent any water leakage from your water tank.

The package includes a sturdy frame flapper that is used for aligning the tank.

On top of it, the flapper will help you in achieving a consistent and powerful flush every single time.

The flapper isn’t only reliable but also made up of corrosion-resistant materials.

You should buy this unit only if your tank is capable of holding at least 3.5 gallons per flush.

Moreover, the solid frame build makes the kit more durable and on top of it, you don’t have to keep replacing the valve every so often.

And, of course, this is one of the few toilet fill valves that are easy to install and use.

Irrespective of whether you are a first-time buyer or a seasoned professional, the installation will not consume more than 15 minutes of yours.

Last but not least, the unit is backed by a 7-year warranty which clearly depicts the trust and confidence of the manufacturer in its offering.

Do I still need to convince you?

Kohler Genuine Part Gp1138930 Silent Fill Toilet Fill Valve Kit

Frankly speaking, the Kohler fill kit is one of the most talked about fill valve kits among our clientele.

It is a value-for-money toilet fill valve that is not only compatible with most toilet types but also equipped with an adjustable valve.

It goes without saying that the brand Kohler doesn’t need any introduction as the brand has proved its mettle time and again.

Effective performance and durability are two important parameters on which this fill valve has performed extremely during our evaluation process.

Both fluid flow and valves are fully adjustable.

It helps the system to become more energy efficient by saving water as well as reducing energy bills.

In order to deal effectively with the standard cleaning requirements, you can adjust the length to up to around 13 inches.

Since the Kohler fill valves mainly consist of high-duty plastics so you can expect them to be relatively durable.

The USP of this unit is the refill rate as it allows you to fill your water tank in less than a minute without making any significant noise.

As compared to other valves, the fill rate of Kohler fill valves is relatively on the higher side making the wait time significantly low.

On the downside, the kit doesn’t come with manual instructions.

Nonetheless, the installation process is quick, easy, and less time-consuming.

American Standard 7381125-400.0070A Fluid Master 400A Universal Toilet Water Fill Valve

The American Standard 7381125-400.0070A Fluid Master 400A Universal Toilet Water Fill Valve is an expensive item and may not be the best choice for someone who is on a shoestring budget.

However, the price is fully justified seeing the features, efficiency, quality, and ease of use features that the unit possesses.

Also, the package includes a couple of accessories for your toilet tank.

The kit includes a Fluidmaster 400A fill valve, coupling nuts, a lock, a refill tube, and a washer as well.

In order to reduce leakage and prevent contamination, the valve includes an anti-siphon feature.

The fill valve comes with a height adjustment feature of up to 14 inches.

Definitely, it offers you a fast and quiet refill which isn’t the case with the standard fill valves.

Not only the wait time is short but also the fill rate is almost twice that of its close competitors in a similar price range.

It is made to fit most of the American Standard toilets and because all the accessories are adjustable, you can get it to fit your toilet tank perfectly.

Trust me, this fill valve is one of the best on our list as it is capable of handling volumes up to 7 gallons which isn’t the case with most standard toilet fill valves.

The installation process is quick, and easy, and will not consume much of your time either, thanks to the included installation instructions.

 Korky 528 QuietFill Universal Toilet Fill Valve

The Korky 528T is an energy-efficient fill valve that is also durable and long-lasting.

In order to get rid of toilet problems such as slow refill, noise, and water leaks, you can take the help of this little beast, and trust me, it will not let you done for sure.

Also, the installation process is quick, easy, and less time-consuming like the aforementioned toilet fill valves.

And, the best part is, you’ll not need any tool for the installation process, thanks to the twist-lock mechanism that the unit comes with.

The fill valve is also good at handling large volumes of water in a hassle-free way.

Moreover, the Korky 528T has a universal design and is compatible with most types of toilets.

On top of it, the 528T consists of a strainer that traps any sediments in the water making it more durable and long-lasting.

TOTO TSU99 A.X Universal Fill Valve

The TOTO TSU99 A.X Universal Fill Valve is one of its kind and could be a great choice for someone who is on a budget.

It is specifically designed to work with TOTO flush tank models.

Features such as EcoPower and the Hydrotect puts this idiosyncratic superlative fill valve in a different league altogether.

For better hygiene and a hands-off experience, EcoPower will do the trick for you.

On the other hand, Hydrotect provides anti-microbial protection by offering self-cleaning.

It consists of unique adjustment features that make the unit compatible with both one and two-piece toilets.

You can adjust both the height and flow rate if you’re using this fill valve on a two-piece toilet.

The fill valve is highly energy efficient as it uses the power that is generated from moving water.

In order to enhance efficiency, the valve aerates the flow of water and also comes with a built-in sensor that prevents the water from running once the tank is full.

Since the valve comes in three different styles so choosing the one that syncs well with your toilet shouldn’t be a problem either for you.

The installation manual makes the entire process smooth and easy.

What is a Toilet Fill Valve?

A toilet fill valve is the name given to the collection of related components inside the toilet tank whose primary function is to manage the water flow that tops off the tank.

At the same time, our readers need to understand that a flush valve performs this function hence it isn’t involved in flushing the toilet.

Don’t get confused between the two components as they are interlinked.

In fact, when you flush your toilet, the fill valve opens and lets the water into the tank.

How Does a Toilet Fill Valve Work?

The toilet fill valve also referred to as a ballcock brings water into the tank once you’ve flushed your toilet, and stays on until your toilet tank has refilled to the desired level.

Whenever water exits your toilet tank, the fill valve will turn on in order to maintain the water level in your toilet tank.

In layman’s terms, a toilet fill valve opens up the supply line to your toilet whenever levels go below the desired water level.

A toilet fill valve is generally positioned on the left side of your toilet tank.

In fact, you’ll notice that a part of the valve is present inside the toilet tank and a tailpiece extends from the toilet tank to the supply line.

Most supply lines also consist of a shutoff valve.

Most toilet fill valves last for at least five years if operated properly.

A toilet fill valve works in conjunction with other components of your toilet so that you can reap the maximum benefits of it.

When you flush your toilet, the flapper opens, leading to the opening of the flush valve.

The water from the tank fills the toilet bowl, and once enough water goes into the toilet bowl, the flapper closes.

At this point, the tank is virtually empty.

On top of it, a toilet float, connected to the fill valve, falls to the bottom of the tank, opening the fill valve.

Moreover, whenever the fill valve opens, water from the supply line enters the toilet tank.

Once the water has entered the tank, the float slowly makes its way back to the top of the tank, slowly closing the valve as the float rises.

In fact, you’ll find an overflow tube that will prevent water from overflowing the tank in case the valve doesn’t completely close.

Though this prevents the tank from spilling on the floor, your water bill may rise when you’ve got a leaky fill valve.

In layman’s terms, it consists of a mechanism to gauge the water level, typically a floater that rises and falls in response to the water level.

As mentioned earlier also, the fill valve will release water when the level falls below a certain maximum point until the maximum level is attained.

And, the best part is, a toilet fill valve will not add much to the weight of the toilet.

However, the role of a toilet fill valve can’t be denied irrespective of its size and weight.

So, you need to ensure that your toilet fill valve is working properly else you may have to deal with a last-minute debacle.

I’m attaching a self-explanatory video for your perusal.

How to Choose a Toilet Fill Valve?

Let’s have a quick look at the factors that you need to know when it comes to choosing a toilet fill valve.

Model and Type

It is important for you to understand that the type of fill valve that you would be needing depends to a large extent on the type of toilet tank that you’ve.

At the same time, it is equally important to identify the last fill valve that you used so that you can easily make out the differentiation.

Though fill and flash valves are available in a vast variety still you need to look for the one that syncs with your toilet size with ease.

In simple words, make sure to check the size of your tank and jot down any information available about the models that can sync with it so that you can avoid any last-minute debacle.


Many of you would be astonished to know that plastic is a better material for a fill valve as compared to any strong metal as it is resistant to both rust and corrosion and as a result, plastic valves are more durable as compared to their metal counterparts.

An iron fill valve can easily corrode and may lead to leakage and malfunctions.

Noise Level 

It is a known fact that a toilet tank makes huge noise during the emptying or refilling process.

So, we at recommends our clientele opt for a fill valve that operates silently or produces relatively less noise.

Flush and Fill Rate

In order to reap maximum benefits from a toilet fill valve, make sure the inlet is capable of supporting the same pressure as the fill valve.

At the same time, you need to understand the fill valve’s flush rate and the toilet’s flush cycle are interlinked so make sure you choose the fill valve that is compatible with your toilet’s flush process.

For modern toilets, a 3 or even 4-inch flush valve will do the trick.

On the other hand, the older variant will need a 2-inch flush valve.

At the same time, you can’t ignore the fact that flush and fill rates are also determined by the size of the toilet flapper which also plays a crucial role in the functioning of the toilet.

Other Reasons

Two important parameters that you must look for are a switch between a half-flush and full flush as well as ease of installation.

Make sure you adjust the height of your fill valve in such a way that the size of the cistern isn’t an issue either.

Many of our avid readers wouldn’t be aware of the fact that water can be saved by having the option to choose between a half and a full flush.

Moreover, the need for a certified technician will be eliminated by a toolless installation.

How to Replace a Toilet Fill Valve?


  • Towels
  • Bucket
  • Channel-lock pliers
  • Fill valve assembly

Step 1: Surrounding area needs to be prepared

If you’re a DIYer then you must be aware of the importance of preparing the surrounding area. You need to place a bucket under the water supply line and also, you need to have a towel on hand in case any water gets onto the floor.

Most importantly, you should’ve pliers and a new flush valve assembly ready before moving to the next step.

Step 2: Disconnect the water supply line as well as turn off the water

First and foremost, you must turn off the water incoming water to your toilet.

You can do so by simply closing the isolation valve which is located on your toilet’s water supply line.

Once you’re done with turning off the water supply, you need to flush the toilet in order to empty the water tank.

By doing so, you’ll be able to reduce the risk of your bathroom water damage.

Moving further, you need to loosen and disconnect the water supply line from the base of your toilet tank using a set of channel lock pliers.

Also, you need to make sure that any remaining water in the line drain can be drained into the bucket, and this can be done by placing the end of the water supply line into the bucket.

If some amount of water has come out of the bucket then you need to clean it with the help of a cloth, sponge, or even a soft towel.

Step 3: Remove the fill valve assembly after unscrewing the locking nut

Since you’ve disconnected the water supply line, you’ve access to the fill valve locking nut on the bottom of your water tank.

You need to loosen the fill valve assembly by unscrewing the fill valve assembly.

If by any chance you’ve not done it then you must remove the tank lid and place it in a safe spot until the job is done.

Now, you need to take out the existing fill valve assembly by reaching into the open tank.

You must put it in your bathroom sink or bucket to catch any remaining water.

Step 4: Float height needs to be adjusted along with new fill valve installation

You need to double-check the new fill valve to make sure that it is compatible with your toilet.

Afterward, remove it from the packaging.

Moving further, you need to place the new fill valve into your open toilet tank and secure it in position by fastening the locking nut on the bottom of your toilet tank.

You need to properly adjust the height of your fill valve as well as the float to ensure that it is sitting at the correct level for your toilet.

It should be about an inch below the top of the overflow tube to properly fill the tank without water draining into the overflow tube.

Step 5: Turn on the water after reattaching the water supply line

This step needs to be performed only after the new fill valve is in place.

You need to tighten the locking nut in order to secure the fill valve assembly.

Afterward, the base of your water tank needs to be reattached to your water supply line.

To begin with, you need to hand-tighten the nut till the time it can’t be turned anymore.

Moving further, you need to use your channel lock pliers to snug up the connection.

Refrain from over-tightening the water supply line as it may lead to the cracking of the nuts.

And, as a result, leakage and potential water damage issue can arise.

On the other hand, if the connection isn’t tight enough then it will lead to leakage of water from the base of the tank.

Step 6: Test your toilet to determine if the repair was successful

Finally, you need to test your toilet to determine whether the repair was successful or not.

You need to turn the water back on at the isolation valve on the water supply line.

While the water begins to fill the tank, check the bottom of your tank as well as the water supply line connection for any leakage.

If your repair is successful then the water will stop flowing into your water tank when the desired water level is reached.

In most cases, the desired water level is an inch below the overflow tube.

In order to ensure your toilet is functioning properly, you need to flush it.

When the tank has been refilled and the flow of water has stopped, you need to put the lid back on the tank and clean up the area.

What are the Types of Toilet Fill Valves?

Let’s have a quick look at different types of toilet fill valves so that you can make an informed purchase decision.

As mentioned earlier also, make sure you’re well aware of the problems associated with each one of them.

Plunger/Piston Ballcock

The plunger/piston ballcock is one of the earliest forms of toilet fill valve that comes with a robust cast brass body which helps in quiet operation.

It consists of a hinged lever assembly above the ballcock that frequently includes thumbscrews at some hinged joints so that adjustment of the lever arm movement can be easily enabled.

toilet fill valve types

As seen in the above pic, it comes with a bottom-fill water discharge tube.

This type of fill valve can be operated by opening and closing a plunger stem against a water input port using a floating ball coupled to a pivoting lever, so the name “ballcock”.

To be honest, these fill valves are not outdated and must be replaced with the upgraded version.

Most importantly, this type of fill valve doesn’t adhere to the anti-siphon protection requirements of the most recent plumbing regulations so you should refrain from using it.

Diaphragm-Type Ballcock

The Diaphragm-Type Ballcock consists of a plastic body and has been around for a while.

Other than a few significant differences, this type of valve fill resembles brass plunger-type ball-cocks.

Either the Diaphragm-type ballcock has a plastic body or a cast brass body.

Diaphragm-Type Ballcock (Plastic Body)

It consists of a diaphragm seal that opens and shuts in order to control water flow.

Most recent anti-siphon diaphragm ballcocks have plastic body construction; if you decide to replace a ballcock-type valve with another, you will likely purchase one. 

Nonetheless, it isn’t counted as a real ballcock because the unit uses a float ball as part of its operating system.

Diaphragm-Type Ballcock

Another variant of the Diaphragm-Type Ballcock is one that consists of a brass body.

The cast brass construction includes the older diaphragm-type ballcock versions, such as the Wolverine Model 58577, which is anti-siphon, and the Mansfield 07 (now discontinued). 

Diaphragm-Type Ballcock (Brass Body)

The bonnet or cover on an older model diaphragm ballcock is cast brass, just like the remainder of the fill valve body. However, the plastic diaphragm activation button is. 

Modern plastic models are frequently used in place of brass ones today.

Float-Cup Fill Valve

As the name suggests, a float-cup fill valve consists of a plastic float-cup and may be recognized by a plastic floating O-cup that revolves around the fill valve shaft in an upward and downward motion.

In fact, a metal spring clip is connected to a metal actuating rod for holding the floating cup.

Float-Cup Fill Valve

Moreover, the tank water level can be changed by modifying the location of the actuating rod’s connection to the float cup.

Furthermore, this type of fill-valve design is easy to clean and maintain and doesn’t need expert guidance either.

The vast majority of toilet fill valves available today have this design, and when it’s time to replace an old ballcock unit with a plunger or diaphragm, this is frequently the replacement of choice.

Floatless Type Fill Valve

The plastic floatless fill valve is a recent advancement in anti-siphon fill valves. These fill valves don’t use any float mechanism to regulate the inlet valve; instead, they use a diaphragm pressure-sensing system. 

Floatless Type Fill Valve

Initially created for low profile/low flow toilet tanks in the 1990s, these fill valves are often inexpensive, but the design is infamous for its patchy reliability. As a result, licensed plumbers typically avoid them in favor of float-cup fill valves.

These valves, which function underwater, are affixed to the tank’s bottom.


In this section, I’ll be responding to queries related to a toilet fill valve in order to help you make an informed purchase decision.

Moreover, if I’ve not answered your question then please feel free to reach out to our core team and they will be more than happy to assist you.

Does it make sense?

Is the fill valve for the toilet universal?

Most toilet fill valves that made it to our list are compatible with valves of the same type- if they’re labeled “universal”.

Let’s understand it with an example.

Universal float cup valves will fit the tanks of most toilet brands as long as they contain a similar valve.

What happens if the toilet valve fails?

A broken fill valve will allow too much water to enter your toilet’s tank leading to an increase in the amount of water that you send down the drain with each flush.

Moreover, you can spot a faulty fill valve just by listening closely to strange sounds that might be coming from your toilet.

Why is the toilet not refilled?

The main reason for a toilet tank not refilling or filling slowly is due to the toilet fill valve.

In layman’s terms, the most common reasons for the fill valve to slow down or no longer fill the tank after the flush are debris issues and the length of time a fill valve has been in use.

Does toilet fill valves leak?

Yes, a toilet fill valve may leak due to many reasons.

Over time, a worn or unaligned fill valve can be a problem.

In fact, it can cause a leak and war on the valve’s components and parts which may complicate the repairing process as well.

Do I need a new toilet fill valve?

Your toilet fill valve will give you a warning sign when it needs to be replaced.

For example, constant sounds of running water from the tank as well as an ineffective flush.

Before replacing your toilet fill valve you may try troubleshooting it by simply adding a few drops of food coloring to the tank.

However, if you couldn’t see the food coloring leak into the bowl, then your fill valve needs to be replaced for sure.

What is the difference between a fill valve and flush valve?

The purpose of a toilet flush valve is to let water gush into the bowl during the flush.

On the other hand, a fill valve refills the tank after the flush.

Why does the toilet fill valve break?

As time progresses, tear and wear will start happening into your fill valve due to frequent flushing.

The more time you flush the more wear will happen to your fill valve.

And, tear and wear of your toilet fill valve will lead to leakage.

How long should the toilet valve last?

Most good quality toilet fill valves will last for 4 to 5 years only if handled properly.

Are all toilet fill valves the same?

No, all the toilet fill valves aren’t the same.

In fact, there are different types of fill valves.

However, all of them do the same job.

What is the standard size of a toilet fill valve?

The standard size of a toilet fill valve is 2 inches.

A 2 inches toilet flush valve will work on most toilets including low-flow, and older models with larger tanks.

Where is the fill valve located?

A toilet fill valve is located on the left side of your 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 shut-off valve.

It’s A Wrap

First and foremost, I would like to thank you for being with us till the end.

Secondly, I would like to bring to your notice that I along with my core team have put loads and loads of effort into coming up with this idiosyncratic superlative piece of information on the topic – toilet fill valve.

And, in case, you liked our effort and want to appreciate us then please do share this post with like-minded people and the ones who are in search of similar pieces of information.

After all, sharing is caring, isn’t it?

Long story short, we’ve tried to the best of our capabilities to cover all the information that you might be needing in making an informed purchase decision.

That’s all, as of now:):)