Toilets are an essential part of any bathroom, and the flush valve is a critical component that allows the toilet to function properly. There are several different types of toilet flush valves available, each with their own pros and cons. In this article, we will examine the five main types of toilet flush valves and discuss their unique features and applications. Having a good understanding of the different valve types will help you select the right one for your toilet installation or replacement project.

Ballcock Flush Valves

The ballcock flush valve is one of the oldest and most common types still in use today. It utilizes a floating ball on the end of a vertical arm to control the water flow into the toilet tank. Here are some key features of ballcock flush valves:

  • Simple and reliable mechanism – Ballcocks have been around for over 100 years and their simple lever and floating ball design has stood the test of time. Few moving parts make them less prone to failure.
  • Adjustable tank water level – The ballcock arm is easy to adjust up or down to set the desired water level in the tank. Matching the proper water volume to your toilet bowl size optimizes flushing performance.
  • Compatible with most toilets – From old to new, most toilet tanks are designed to work with a standard ballcock valve. They are still commonly found as original equipment on many toilets.
  • Prone to corrosion and mineral buildup – The metal arm and ball can corrode over time leading to leaks. Mineral deposits on the ball and valve seat can also prevent proper sealing and operation.
  • Noisy tank refilling – As the ballcock opens, water rushing into the tank can be quite loud compared to newer valves.

Ballcock flush valves are an economic choice but regular inspection and occasional part replacement are required to keep them operating properly. The noise of tank refilling is also a downside in some situations.

Flapper Flush Valves

The flapper flush valve utilizes a rubber flap attached to a frame mount on the overflow tube to control water release from the tank into the toilet bowl. Here are some notable flapper valve features:

  • Simple and efficient water flow control – The flapper seal provides a reliable seal over the flush valve opening until actuated by the flush lever/button.
  • Quiet tank refilling operation – Waterflow is regulated through the ballcock or fill valve for quiet refilling compared to ballcock type flush valves.
  • Prone to warping and deteriorating – The rubber flap can warp or deteriorate over time allowing the valve to leak and reducing flush performance.
  • Frequent maintenance required – Flappers typically need replacement every 3-5 years to maintain proper flushing.
  • Susceptible to obstructions – Objects or debris can prevent the flapper from fully closing and sealing the flush valve opening.

Flapper flush valves are common on modern toilets and easy to find replacement parts for. Their main downside is needing frequent replacements as the flapper deteriorates with age. Care must also be taken to prevent tank obstructions that could impact sealing.

Canister Flush Valves

Canister style flush valves utilize a cylindrical canister assembly inside the tank to control water flow into the toilet bowl. Some notable features include:

  • Enables powerful, efficient flushing – The large flush valve opening and flow rates enable strong siphon action in the toilet trapway for complete waste removal.
  • Quiet operation – Water flows smoothly through the canister assembly for quiet flushing. There is no flapper to create noise against the flush valve opening.
  • Durable and long-lasting – Canister valves are highly durable with a lifespan of 10+ years. Minimal maintenance is required.
  • Compatible with 1.6 gpf toilets – Ideal for modern high-efficiency 1.6 gpf or less toilets to provide sufficient flush power.
  • Higher replacement part costs – While infrequent, canister valve repairs can be costly compared to basic flapper or ballcock valves.

Canister flush valves are found on most modern high-efficiency toilets. Their durable construction and powerful flushing performance make them an excellent choice. Cost of maintenance is the main tradeoff.

Dual Flush Valves

Dual flush valves provide a choice of two flush volumes – a lower volume for liquid waste removal and a full volume for solid waste removal. Key features include:

  • Water conservation – Option of reduced flush volume can save significant water usage over time.
  • Flexibility in flushing – Having both lower and higher flush capability improves performance for both types of waste removal.
  • More complex mechanisms – Having dual flush buttons and control valves makes these systems more complex than standard single flush valves.
  • Higher replacement part costs – Due to more moving parts, repairs on dual flush valves typically have higher part costs.
  • Incompatible with some toilets – Dual flush valves usually cannot be added to an existing single flush toilet.

Dual flush toilets with appropriate valves are recommended for residential and commercial applications looking to maximize water conservation without sacrificing flush performance.

Pressure Assist Flush Valves

Pressure assist flush valves utilize compressed air in the tank to pressurize the water during flushing for a stronger siphon effect. Some notable characteristics include:

  • Powerful flushing performance – The added pressure enables complete waste removal even with lower 1.0 gpf toilets.
  • Self-cleansing capabilities – The pressurized water flow helps keep the bowl and trapway clear of waste buildup.
  • Noisy operation – As pressurized air escapes during flushing, these systems are typically louder than gravity flush valves.
  • Specialized replacement parts – Repairs require specific pressure valve components that have limited availability.
  • Higher upfront cost – Pressure assist toilets have a higher initial purchase price than comparable gravity flush toilets.

Pressure assist flush systems are ideal for applications that demand maximum flushing capability from low volume toilets. The tradeoffs are higher noise levels and maintenance complexity.

Choosing the Right Flush Valve

When selecting a flush valve, the most important factors to consider are toilet bowl type, desired flushing performance, water efficiency, and maintenance requirements. Here are some general guidelines:

  • Older 3.5+ gpf toilets – Ballcock or flapper flush valves are appropriate.
  • Modern 1.6 gpf gravity toilets – Flapper, canister, or dual flush valves recommended.
  • Pressure assist 1.0 gpf toilets – Matching pressure assist flush valve required.
  • Maximum flushing power needed – Canister or pressure assist valves best choice.
  • Water conservation priority – Dual flush offers flexibility for light or heavy flushing.
  • Low maintenance preference – Canister valves require the least frequent repairs or parts replacement.
  • Budget conscious – Ballcock flush valves are the most economical choice.

Taking the time to match the flush valve technology to the specific toilet type, flushing requirements, and budget will lead to optimal long-term toilet performance and satisfaction. Paying attention to flush valve condition and making repairs or replacements as needed is also critical for avoiding major toilet problems down the road.

Frequently Asked Questions About Toilet Flush Valves

Toilet flush valves may seem simple on the surface, but there are a lot of details worth understanding to select, maintain, and repair them properly. Here are answers to some of the most common questions.

What are the main types of toilet flush valves?

The major types of flush valve systems are the ballcock, flapper, canister, dual flush, and pressure assist. The ballcock and flapper are the traditional choices while canister, dual flush, and pressure assist incorporate newer technology.

How can I tell when my flush valve needs replacement?

Signs that a flush valve requires replacement include frequently double flushing, weak or sluggish flushes, the toilet running constantly, the valve not fully closing and sealing, and visible deterioration of valve components.

What is an overflow tube and why does my toilet have one?

The overflow tube is a vertical pipe installed in the toilet tank to limit water rising should the flush valve malfunction and fail to close. This prevents water overflowing from the tank. It also typically houses the flapper flush valve.

Why does my toilet make noise when refilling the tank?

Noisy tank refilling is typically caused by an outdated ballcock style flush valve. The rushing water creates the noise as the tank refills. Newer flapper, canister, and pressure assist valves greatly reduce this noise.

How do dual flush toilet valves work?

Dual flush valves have two buttons or controls. One button opens a valve for a reduced water volume flush for liquids. The other button opens the full valve for a full volume flush to clear solids.

Are pressure assist toilets better than gravity flush?

Pressure assist toilets use compressed air to pressurize the water during flushing. This enables superior waste clearing capability even with lower water volumes. They are an excellent choice when maximum flushing power is needed.

Should I completely shut off the toilet water to replace a flush valve?

You can simply close the fill valve at the bottom of the tank to replace a flush valve. This keeps the tank full without having to shut off plumbing below the toilet. Make sure to use towels to soak up any spillage.

What causes a toilet to run constantly and how do I stop it?

A continuously running toilet is almost always caused by a faulty flush valve that fails to fully close and seal the tank water in. This is most commonly due to problems with a flapper valve. Replacing the valve stops the running.

Why does my new flush valve leak around the overflow pipe?

Improper sizing or seal of the gasket around the overflow tube is the likely cause of water leaking from a newly installed flush valve. Be sure you have the properly sized gasket and that it is fully seated flush to the valve.


There are five main types of toilet flush valve systems, each with their own advantages based on toilet type, performance needs, desired features, and budget. Paying attention to proper flush valve selection, routine maintenance, and timely replacement when issues arise allows your toilet to function reliably for many years. Understanding the differences between the ballcock, flapper, canister, dual flush, and pressure assist valve designs provides the knowledge to make the best choice for your toilet.