Types of Toilet Flush Systems

It may not seem important but the type of toilet flush system you choose can make a difference in how much water you use each month. Each time you flush the toilet, the toilet bowl has to be refilled with the same amount of water that was just flushed.

There are four different types of toilet flush systems that will determine just how much water is used during each flush. There are different flushing mechanisms, flushing levers, and flushing handles that can all contribute to the efficiency of each toilet flush system.

What are the Different Types of Toilet Flush Systems?

You should choose the type of toilet flush system that fits both your budget as well as your water efficiency needs.

toilet flush system

There are four classifications of toilet flush systems: dual flush systems, gravity flush systems, pressure-assist systems, and vacuum-assist systems.

Dual Flush Systems

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Dual flush systems are designed to give the user the option to flush fully or partially. A partial flush uses less water and can be used when you don’t need to flush toilet paper or other waste, whereas a full flush will flush all of the water within the toilet bowl.

Gravity Flush Systems

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Gravity flush systems use gravity to flush the water from the bowl when the valve is opened by the handle lever. Older toilets with gravity flush systems can use a lot of water during each flush. Fortunately, the design of gravity flush systems has improved over the years and they now use much less water than before.

Pressure-Assist Systems

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Pressure-assist systems use pressure to flush the water from the bowl when the lever opens up the flush valve. The pressure causes the toilet bowl to flush with a powerful force. This can also cause the toilet to be one of the noisiest on the market.

Vacuum-Assist Systems

Vacuum-assist systems are new to the market. They use a vacuum tank to create a suction to flush the water from the tank and bowl of the toilet.

Related: How to Flush a Toilet when water is turned off.

What is the Difference Between Flush Valve and Gravity Feed?

The flush valve in a toilet is the piece within the tank that pushes the water into the bowl of the toilet. The larger the valve, the faster (and better) the flush will be. The flush valve will always stay the same. This means if your toilet has a 2″ flush valve, you will only be able to replace it with another 2″ flush valve. You can’t replace it with a 3″ flush valve.

A gravity feed toilet is the most common type of toilet on the market. They are commonly seen in residential homes or apartments. When you push the handle on the gravity-fed toilet, the lever will lift the flushing valve and allow the water to flush the waste from the toilet bowl.

What is the AquaPiston flushing system?

AquaPiston flushing technology uses a canister called the AquaPiston. The AquaPiston canister allows for 360-degree flushing throughout the entire toilet flush system. The AquaPiston flushing system doesn’t require a flapper.

Instead, the valve is opened and the water flushes the toilet bowl from all directions rather than just one. The AquaPiston flushing system has a 3.25″ valve that creates a powerful flush throughout the bowl.

Kohler has patented the AquaPiston flushing system and created a better flushing system to help you maintain a cleaner toilet bowl. Because the AquaPiston flushing system uses a canister, it allows the water from the tank to come down on all 360 degrees of the bowl using a single yet powerful jet of water. This ensures that no waste sticks to the side of the bowl as it is flushed.

Which Flush Type Uses Waterline Pressure?

Pressure-assisted flush systems use waterline pressure to create the flush. The benefit of waterline pressure toilet flush systems is that they use a minimal amount of water per flush; therefore, your water savings is at a maximum.

The disadvantage of a pressure-assisted flush system is the amount of noise that is created from the toilet when it’s flushed.

What Type of Toilet Flush is Best?

Typically, you will want to choose a toilet flush that saves as much water as possible per flush. For commercial uses that offer public restrooms, pressure-assisted flush systems are often the best option because they use the least amount of water per flush. They are also the loudest which is typically not considered a disadvantage in a commercial setting.

For residential use, the best type of toilet flush is a dual flush system. With a dual flush system, you get the option of making a partial flush or a full flush. This gives you the best of both worlds. You can save water per flush when you only need to make a partial flush. You can also still make a full flush for those times when you need to flush waste and toilet paper.

Gravity flush systems are still a tried-and-true method of toilet flush systems and they have improved water efficiency over the years. No more wasting gallons of water per flush with outdated gravity flush systems. Now there are gravity flush systems that use as little as one gallon of water per flush.


There are four main types of toilet flush systems and each system has its benefits and disadvantages. The best all-around toilet flush system is likely the dual flush system simply because it gives you the option of the type of flush you need to use. It also saves the most amount of water without sacrificing cleanliness on the toilet bowl.

Pressure-assisted flush systems use a lever to open up the valve and flush the water through the bowl. The pressure from the valve causes the water to flush through the bowl with power as soon as the valve is opened. These are extremely effective and efficient toilet flush systems but also the loudest.

The toilet flush system that is the newest option on the market is the vacuum-assist flush system. Because it is so new, there aren’t a lot of options on the market for this design. This can make purchasing replacement parts difficult for this type of system.

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