Toilet Fill Valve: Types and How it Works - High Shower (2023)

The fill valve for the toilet is the most significant component of the gravity flush toilet. It regulates the water flow into the holding tank, opening the water flow as the flush cycle empties the tank and closing the water flow once the tank has been filled to the appropriate level.

The toilet fill valve regulates the flow of water into the toilet tank after a 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.

You should know the types of toilet fill valves and the common toilet fill valve problems to make the most of your toilet. While it’s a small part of the toilet’s setup, it still plays a major role.

Toilet Fill Valve: Types and How it Works - High Shower (1)

What is a toilet fill valve? How does it work?

The toilet fill valve, a collection of related components inside the toilet tank, manages the water flow that tops off the tank. Since the flush valve performs this function, it is not involved in flushing the toilet.

However, the two are connected because when you flush the toilet, the fill valve opens and lets water into the tank.

It consists of a mechanism to gauge the water level, typically a floater that rises and falls in response to the water level. The fill valve releases water when the level falls below a certain maximum point until the maximum level is attained.

Others utilize a pressure-sensing device to determine whether the toilet tank is filled with water.

The toilet fill valve doesn’t add much to the weight of the toilet but its role is one of the most important in its functioning.

Types of toilet fill valves

The main types of toilet fill valves are as follows:

1. Plunger/Piston Ballcock

Toilet Fill Valve: Types and How it Works - High Shower (2)

One of the earliest toilet tank fill valve designs is the plunger or piston-style fill valve (ballcock). They have a robust cast brass body that allows for quiet operation.

This type of ballcock is built with a hinged lever assembly above the ballcock that frequently includes thumbscrews at some hinged joints to enable adjustment of the lever arm movement.

It also has a distinctive bottom-fill water discharge tube. These fill valves operate by opening and closing a plunger stem against a water input port using a floating ball coupled to a pivoting lever, hence the name “ballcock.”

These outdated fill valves should be changed if you still have one of them since they don’t adhere to the anti-siphon protection requirements of the most recent plumbing regulations.

2. Diaphragm-Type Ballcock (Plastic Body)

Toilet Fill Valve: Types and How it Works - High Shower (3)

Diaphragm ballcocks have been around for a while, like plunger or piston ballcocks. They resemble brass plunger-type ball-cocks in many ways (they have float balls, too), but there are also some significant differences.

One such distinction is the anti-siphon nature of these ballcocks. They can have a cast brass body or a body made of plastic. This kind of ballcock features a diaphragm seal that opens and shuts to control water flow rather than a plunger stem with a washer that seals against the water input port.

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.

However, because it uses a float ball as part of its operating system, this all-plastic variety nevertheless counts as a real ballcock.

3. Diaphragm-Type Ballcock (Brass Body)

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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).

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.

4. Float-Cup Fill Valve

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Plastic float-cup fill valves are a more “contemporary” anti-siphon fill valve design that Fluidmaster first presented in the late 1950s.

This kind may be recognized by a plastic floating O-cup that revolves around the fill valve shaft in an upward and downward motion. A metal spring clip to a metal actuating rod holds the floating cup.

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

This fill-valve design is quite common and straightforward to maintain. 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.

5. Floatless Type Fill Valve

Toilet Fill Valve: Types and How it Works - High Shower (6)

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.

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.

How to choose a toilet fill valve

Below are some of the factors you need to watch out for when selecting a fill valve:

1. Model and type

The type of fill valve you require depends on the type of toilet tank you have. To know the type of fill valve to buy while replacing your fill valve, you must first identify the previous one.

Despite the variety of flush valves available, your options may be constrained by the size of your toilet tank. As such, check thoroughly before purchasing a toilet fill valve.

2. Material

Although plastic may not always be as strong as metal, it is a better material for flush valves. Since they are resistant to rust and corrosion, plastic fill valves are more durable than their metal alternatives. Metal fill valve corrosion frequently causes leaks and malfunctions.

3. Noise level

The toilet tank makes a lot of noise when emptying and refilling, which may be rather bothersome. Therefore, buying a fill valve that offers silent operation is advisable if noise annoys you significantly and makes you irritable.

4. Fill and flush rate

While the only thing to consider might be how quickly it fills and flushes, this is different. The toilet tank’s fill valve depends on the entrance where the water enters.

Therefore, for the toilet flush valve to function at its best, the inlet must be capable of supporting the same pressure as the fill valve.

The fill valve’s flush rate and the toilet’s flush cycle are intimately related. Choose one that is compatible with your toilet’s flush process. While most modern toilets demand a three or 4-inch flush valve, most older ones can use a 2-inch one.

The flush and fill rates are also determined by the size of the toilet flapper which also plays a major role in the functioning of the toilet.

5. Other attributes

A switch between a half-flush and a full flush and ease of installation are other qualities to look for in a flush valve. The height of your fill valve should be adjustable to ensure that the size of your cistern won’t be a problem.

Water can be saved by having the option to choose between a half and full flush, and a toolless installation will eliminate the need for a plumber.


A toilet system that releases water into the toilet bowl has a toilet valve as a critical component. You can awaken to a bathroom with a sink and toilet that are flooded if this task isn’t done correctly.

Therefore, get a high-quality toilet valve to prevent such a problem.

Make sure it is composed of robust materials like plastic so that it’s rust and corrosion-resistant, in addition to factors like silent operation and leak-proof construction.

Identify the type and model so it can easily fit into your toilet system and has extra features like a half and full flush and an adjustable height for simple use.


Are there different toilet fill valves? ›

There are several different types of fill valves commonly found in toilets, and you will need to be able to identify your type in order to make adjustments or replacements to yours.

What is the difference between a fill valve and a ballcock valve? ›

The fill valve (sometimes referred to as a ballcock) brings water into the tank after the toilet is flushed and stays on until the tank refills. Any time water exits the tank (such as when a flapper is leaking), the fill valve will turn on in order to maintain the water level.

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

There are really only two main toilet tank parts: The toilet flush valve, which lets water gush into the bowl during the flush, and the fill valve, which lets water refill the tank after the flush.

How do I know which toilet fill valve I need? ›

An easy reference is to look at the size of the flush valve drain opening in the bottom of the tank. If it's about the size of an orange or baseball, you need a 2 inch seal. If it looks more like the size of a grapefruit or softball, you need a jumbo 3 inch seal.

What is the difference between a 2 and 3 flush valve? ›

Look at the flush valve drain opening at the bottom of your tank. If the opening looks about the size of a baseball or orange, you need a 2″ flapper. If the opening looks about the size of a softball or grapefruit, you need a 3″ flapper.

What is the difference between high and low pressure ball valves? ›

​As opposed to the Oliver low-pressure ball valves, the high-pressure ball valves are typically used to withstand high operating pressures and they keep streams of fluid under control whilst safely isolating or allowing the system fluid to pass through.

How does a ballcock fill valve work? ›

The valve is connected to the incoming water supply, and is opened and closed by the lever which has the float mounted on the end. When the water level rises, the float rises with it; once it rises to a pre-set level, the mechanism forces the lever to close the valve and shut off the water flow.

What are the four types of ball valves? ›

The 4 Types of Ball Valves – Single Body, Split Body, Top Entry and Welded.

What are the two types of flush valves? ›

Types of Toilet Flush Valves

Toilet flush valves come in the following formats: standard, 3-inch, 4-inch, tower-style (also called canister-style), and dual flush valves.

How does a dual flush fill valve work? ›

Dual Flush is an interactive water saving design for a toilet. It is created with the internal flush valve allowing two separate flushing volumes for disposing waste. This type of cistern gives you the choice between a half flush for disposing liquid waste or a full flush for disposing solid waste.

What valve automatically fills toilet tank? ›

The fill valve is usually a device mounted on the left side of the toilet. The main way to identify a fill valve is to look for the tallest item in your tank. It is usually a vaguely cylindrical design that runs from the bottom of the tank to the top.

How often should a toilet fill valve be replaced? ›

Toilet Parts

The toilet's flush valve will typically last 6-7 years. A toilet fill valve might only last four to five years. In general, you should expect to replace the parts in your toilet every so often while keeping the actual bowl in place.

What is the most common toilet valve? ›

Most toilets have a standard flush valve. This is just a basic 2-inch flush valve and flapper that lifts up when you push the toilet handle down. Standard flush valves may be found on low-flow toilets and on some older toilets with large tanks.

What is a Douglas valve? ›

Douglas Style Brass Flush Valve. These flush valves have a longer-than-normal 1 3/4″ shank on them and are intended for use in low tank toilets, not close coupled. Supplied with tank ball, washer, guide, and upper and lower lift wires.

Do I need high or low-pressure float valve? ›

A Low-Pressure Ball Float Valve is provided with a larger hole within the valve assembly (looking down inside the threaded end) to fill the tank or cistern up more quickly, however, if the water pressure is too high this will result in excessive noise or water hammer.

What is the best valve for high-pressure water? ›

Needle valves are ideal for applications where the fluid needs to be shut off gradually, or a very low flow rate is desired. Despite the small size of the water inlet and internal spindle, needle valves are capable of withstanding very high pressures.

What is the difference between a Type 1 and Type 2 ball valve? ›

Part 2 ballcock valves are quieter than the part 1 version and give better protection against backflow. Use in cold water storage tank, central heating feed and expansion header tank, etc.

What is a Portsmouth valve? ›

Often called a "Portsmouth valve", these brass BS1212/1 ballcock / ball float valves are used as a cold water storage tank or central heating feed and expansion header tank inlet / fill valve.

How do I increase water pressure in my toilet? ›

6 Ways to Get a Stronger Toilet Flush in 2023
  1. Clean The Rim Jets. The rim jets are holes in the toilet's base where water comes from when you flush. ...
  2. Fix Any Clogs. ...
  3. Adjust The Water Refill Tube. ...
  4. Reposition or Replace The Flapper. ...
  5. Open The Water Valve. ...
  6. Adjust The Float.
Feb 16, 2023

What is a float valve in a toilet? ›

It's a device that lets the water fill into the toilet tank and prevents it from overflowing. The toilet float is also called a ballcock or a float valve. Old-style toilet floats had a plastic ball with a metal rod attached to them.

What is a trunnion valve? ›

Trunnion ball valves are quarter-turn valves used to stop or start the flow of a media in a pipe. The most common type of ball valve has a “free floating” design, so the trunnion type is a design change.

What are the 5 major types of valves? ›

The following types of valves are used in a variety of applications, these descriptions may provide a basic guideline in the selection of valves.
  • BALL VALVES. ...
  • GATE VALVES. ...
Oct 26, 2016

How do you know if a ball valve is open or closed? ›

Ball valves are perhaps the easiest valve to see if they are open or closed. If the handle on top is parallel to the valve, it's open. Likewise, if the handle is perpendicular to the top, the valve is closed.

What is the difference between standard and high toilet? ›

ADA-compliant chair height is a minimum of 17 inches and a maximum of 19 inches from the finished floor to the top of the toilet seat. Standard height toilets are typically 14 to 15 inches in height.

What are the different types of toilet fittings? ›

There are two types of toilet seat fixings: Bottom Fixings and Top Fixings. Top fixing toilets seats work by feeding two bolts into the pan which are then tightened from the top. Bottom toilet seat fixings are fitted from the top and then tightened from underneath, often with wing nuts.

What are the two different toilet heights? ›

Toilet height is measured from the floor to the top of the seat. Most often, toilets fall somewhere between 15" and 19", with standard toilets coming in under 17". Chair-height toilets measure 17" or more.

Are all fill valves the same? ›

There are different kinds of toilet fill valves, but they all do the same job: refilling your cistern so it's ready for the next flush (link to toilet flush), then shutting off the flow of incoming water. There are two ways a toilet valve can shut off: using an upturned or float cup and a ball valve.

What are the names of toilet valves? ›

Toilet flapper: Situated at the base of the tank, this lifts and triggers a flush of water to the toilet bowl. It is also called a flapper valve. Toilet lever: Connected to the handle, this lever lifts the rubber flapper, which triggers the flush. It is also called the lift rod.

What type of valve is a fill valve? ›

The fill valve is anti-siphon. Rather than a plunger stem with a washer seal against the water inlet port, it has a diaphragm seal. This seal opens and closes to control water flow.

Why does my dual flush toilet keep filling after flush? ›

The most common cause is a flush valve seal worn out, deformed, or unclean. Water may leak continuously if the flush valve seal is not adequately sealed. Another possibility is that the tank is constantly filled due to a broken fill valve.

What does dual flush mean on a toilet? ›

A dual flush toilet is a variation of the flush toilet that uses two buttons or a handle mechanism to flush different amounts of water.

What is a mix flush valve? ›

The Flygt Mix-Flush™ System automatically flushes accumulated fats and solids into suspension during initial operation of the pump. The system consists of the Flygt 4910 Flush Valve, Impeller and Volute. The operation of the valve depends only on the pump flow and pressure.

Why is my toilet running after I flush? ›

The three most common causes are a broken or dirty flapper, too long or too short of a chain between the flush lever and the flapper or a float that is out of position.

Is water supposed to come out of the top of the fill valve? ›

The water is leaking out of the cap simply because the pressure pushing up on the cap is very high, and the cap cannot handle that high pressure. However, the high-pressure water should be escaping into the toilet tank and not pushing against the cap.

Why does my toilet fill valve keep turning on and off? ›

A toilet that cuts on and off by itself, or runs intermittently, has a problem that plumbers call a "phantom flush." The cause is a very slow leak from the tank into the bowl. This problem is almost certainly caused by a bad flapper or flapper seat.

What valve controls the water flow delivered to a flush toilet? ›

A Flush Valve, as the name suggests, is a component found inside a toilet cistern that is used for flushing out the contents of the toilet, into a sewer system/septic system through a drainpipe.

What is the proper fill valve height? ›

Critical Level Mark (Indicated with the letters CL on the fill valve) of the fill valve must be 1 inch above the top of the overflow pipe.

What is the most common problem associated with the fluidmaster? ›


When it's not flushing or refilling, flush/refill sounds or short bursts of air every so often may come from the fill valve. Constant leaks could need a new toilet seal or other repair parts.

How high should a toilet supply valve be? ›

Toilet supply line (height): Ideally, the toilet's water supply line enters the room at 8 1/4 inches above the floor. More broadly, this cold-water-only pipe creates one hole between 5 and 10 inches above the floor.

Are all toilet fill valves the same size? ›

A flush valve is a part inside the tank of a toilet that moves the water into the bowl. Toilet flush valves come in different sizes ranging from 2 to 4 inches, depending on the toilet design.

Are toilet fill valves a standard size? ›

Most toilets will have a 2-inch drain or a 3-inch drain. Fluidmaster manufactures a standard or universal size of flush valves with flappers and are among the most common flush valves to be used.

What are the different styles of toilet flush valves? ›

Types of Toilet Flush Valves

Toilet flush valves come in the following formats: standard, 3-inch, 4-inch, tower-style (also called canister-style), and dual flush valves.

Are most fill valves universal? ›

Most toilet fill valves are compatible with valves of the same type—if they're labeled “universal.” For example, universal float cup valves will fit the tanks of most toilet brands as long as they contain a similar valve.

Do I need a new toilet fill valve? ›

You can spot a faulty fill valve by listening closely to strange sounds that might be coming from your toilet. The sound of water constantly running through the tank can indicate fill valve problems. Place a few drops of food coloring into the tank and watch to see if the colored water leaks out into the bowl.

How much does a plumber charge to replace a toilet fill valve? ›

$75 - $200

How long does it take to change a toilet fill valve? ›

Most do-it-yourself homeowners can handle this project in about 60 minutes. All you need is the most basic understanding of how toilets work, a replacement fill valve kit, and the instructions above.

What is the difference between flush valve and flush plate? ›

Flush plates: Flush plates are connected with concealed water tanks. It is an operating mechanism with two buttons, wherein the user can use less or more water as per the requirement. Flush valves: If you want a toilet flush tank that releases high-pressure water, then a flush valve ideal.

What is a Coast style flush valve? ›

Coast Tank Flapper Toilet flappers are used to provide a water seal in the toilet tank and allow water to exit to bowl upon flushing. A functioning flapper will help control the amount of water that is released into the bowl therefore can help save on water usage with every flush.


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