The Pros and Cons of Pressure-Assisted Toilets – Are They a Good Choice?

There is a slight but significant difference between pressure-assisted toilets and gravity-flush toilets. While they operate on the same principle, the mechanics vary slightly. We will walk you through the advantages and disadvantages of a pressure-assisted toilet so you can make an informed choice. Read on to find out whether this type of toilet is right for your house!

Pressure-Assisted Toilets: What Are They?

Pressure-Assisted Toilets: What Are They

A pressure-assisted toilet is a toilet with a secondary tank that resides inside your main toilet tank. This is known as a pressure vessel. It holds compressed air that mixes with incoming water directly from the supply line to generate a powerful flush.

Difference Between Gravity-Flush and Pressure-Assisted Toilets

If you are wondering how a pressure-assisted toilet differs from a gravity-flush toilet, the answer is that pressure-assisted toilets contain a minor modification that isn’t noticeable from the outside. You have to remove the tank lid to see the difference between the two.

Gravity-flush toilets depend heavily on gravity to remove all the water from the tank and put it in the bowl when flushing the toilet. For this to happen, water must move quickly from the tank to the bowl.

Suddenly dumping volumes of water in the toilet bowl is what generates a siphon effect in the toilet trap. This is the reason why modern toilets contain a wider flush valve, as it quickly moves water from the tank to the bowl while using less water.

Pressure-assisted toilets are more efficient at getting rid of solid waste than gravity-flush models. Pressurized water generates a stronger siphon, which allows waste to move through the trap more forcefully. This means you won’t need to flush twice to get rid of waste, nor will you have to deal with a clogged toilet.

The downside is that pressure-assisted toilets cost more than gravity-flush ones. While there are some gravity-flush toilets that cost more, they generally have more features.

The Pros of a Pressure-Assisted Toilet

There are several pros of pressure-assisted toilets, including:

  • Powerful flush. Most people dislike the need to flush twice when using the bathroom. This type of toilet solves that issue.
  • Clogs less. With this toilet, plungers are needed less often. They are significantly better than any other toilet type at flushing solid waste. Pressurized water forces waste through the trap and is removed through the drainpipe each time.
  • Water-efficient. While you may expect these toilets to use more water because of the water being forcefully pushed through the system, they are surprisingly water-efficient. These toilets utilize 1.1-1.2 gallons per flush, compared to 1.28-1.6 gallons per flush for gravity-assisted toilets.
  • Tank doesn’t sweat. Condensation forms on toilet tanks in rooms with high humidity. This is caused by temperature differences between the inside of your tank and the surrounding environment. The double-tank system in pressure-assisted toilets keeps the tank insulated and eliminates toilet sweat.
  • Stays cleaner. Since the system delivers a great deal of pressure, the water level is higher than in other toilets. Waste doesn’t stick to the toilet bowl surface, which means the bowl will stay cleaner longer.

The Cons of a Pressure-Assisted Toilet

While the pros of a pressure-assisted toilet seem delightful, there are some drawbacks to this type of toilet, such as:

  • Loud flush. Pressurized toilets are similar in sound to those on an airplane. As the water forcefully leaves the pressure vessel, a forceful flush is generated and there is a loud flushing noise. After a while, most homeowners become accustomed to the noise.
  • Difficult to Get Replacement Parts. It is easier to find replacement parts for ordinary toilets than for pressure-assisted ones. Since these toilets are not that common, stores don’t typically have replacement parts in stock.
  • Higher Cost. Compared to gravity-flush toilets, pressure-assisted toilets cost more. This is because manufacturers need to outsource pressure vessels from third parties.

How They Work

Pressure-assisted toilets work by allowing a pressure valve to draw in air directly to the pressure vessel. The inflowing water from the supply line is then forced into the pressure vessel. When the toilet is flushed, compressed air forcefully pushes water directly into the toilet bowl. Strong suction/siphon action is generated in the toilet trap, which flushes the toilet.

After waste is removed, the pressure vessel sucks in additional water and air for the next flush.

Our Recommendation for the best Pressure Assisted Toilet

Kohler K-3493-0 Highline Classic Pressure Lite Comfort Height Elongated 1.6 gpf Toilet

Our recommendation for the best pressure assisted toilet would be the Kohler K-3493-0 Highline Classic Pressure Lite Comfort Height Elongated 1.6 gpf Toilet:


  • Size: 30-1/8″L x 21-1/4″W x 31-1/4″H
  • Has A Pressure Assist flushing system
  • Two-piece
  • Elongated bowl
  • 12″ rough in
  • Including a trip lever, less seat and supply
  • Pressure Lite toilet that utilizes a 1.6-gallon per flush
  • Advanced noise-mapping and frequency analysis will ensure quiet performance
  • Large 10″ x 12″ water surface helps to keep the bowl clean and will reduce odor
  • Pressure Assist Technology uses compressed air in the reservoir to deliver robust flushing power

Types of Pressure-Assisted Toilets

While we have already discussed common pressure-assisted toilets, there are ones that differ slightly. When low-flow toilets were created to conserve water, manufacturers were faced with the challenge of designing a toilet that flushed strongly with a single flush and wouldn’t clog.

They discovered it was possible to do this only with a toilet that held 3.5 gallons per flush as opposed to 1.6 gallons or less. To compensate, they created toilets with ¾” flush valves and an extra-large trap way.

Tankless Toilet

A tankless toilet is a toilet without a tank. If you are wondering how it flushes, the tank is a reservoir that supplies the bowl with the water needed to flush the toilet each time. The tank is found at the top of the bowl to allow water to gain force as it goes down.

Tankless toilets contain a small pump supplying the bowl with high-pressure water that will sufficiently flush the contents. This eliminates the need for a tank. Tanks are generally installed because most houses don’t have enough water pressure to adequately flush a tankless toilet.

Upflush Toilet

Pressure-Assisted Toilet

Upflush toilets are installed below grade, or far from your sewer lines. They pump solid waste horizontally and vertically, making them ideal for basement bathrooms. They afford the opportunity of adding extra bathroom fixtures as well.

These toilets have a macerator at the rear. This contains blades rotating at high speeds to break down waste into a slurry before pumping it out.

Rear-Discharge Toilet

Rear-discharge toilets get rid of water from the back and through the bathroom wall. They are best for bathrooms that are far away from sewer lines and without floor drainage systems.

The issue with this type of toilet is that the gravity flush system may not be sufficient since the toilet trap is shorter. The siphoning effect of this model isn’t as strong, thereby generating a weaker flush.


There are both advantages and disadvantages of pressure-assisted toilets. You should weigh the pros and cons of each in determining if this is the best model for your home. While these types of toilets are great on water consumption, easy to clean, and sweat less, they are also louder and cost more.

Also Read: Save Time and Money With Up Flush Toilets