What Is a Pressure-Assisted Toilet? Benefits and Considerations

A pressure-assisted toilet is a type of toilet that uses both gravity and pressurized air to flush waste more effectively than a standard gravity-flush toilet. Unlike a gravity-flush toilet which relies solely on the force of gravity to siphon water and waste, a pressure-assisted toilet uses a sealed tank that pressurizes air inside the tank to force water into the bowl at a high velocity when flushed.

Pressure-assisted toilets provide a number of potential benefits compared to standard gravity-flush toilets. Some of the key advantages include increased flushing power, improved bowl cleaning, lower water usage per flush, and reduced risk of clogs. However, pressure-assisted toilets also have some drawbacks to consider before installing, such as higher cost, noisier operation, and more complicated repairs.

In this comprehensive guide, we’ll take an in-depth look at everything you need to know about pressure-assisted toilets, including:

A pressure-assisted toilet is a type of toilet that utilizes both gravity and pressurized air to create a strong siphon during flushing. Unlike a gravity-flush toilet which only uses the force of gravity to siphon water into the bowl, a pressure-assisted toilet has a tank that is sealed and pressurized with air. When the toilet is flushed, the pressurized air in the tank pushes the water out of the tank and into the toilet bowl with extra force. This creates a strong siphon and a powerful flush. The use of pressurized air allows the toilet to flush using less water than a gravity-flush toilet, while still providing an effective cleaning flush. Pressure-assisted toilets are designed to produce a commercial-grade flushing performance in residential settings.

How Does a Pressure-Assisted Toilet Work?

To understand the benefits of a pressure-assisted toilet, it helps to first look at how they work in comparison to a standard gravity-flush toilet.

Gravity-Flush Toilet Mechanics

A gravity-flush toilet uses the force of gravity to siphon water from the tank into the bowl when flushed. Here is an overview of the flushing action in a gravity-flush toilet:

  • The toilet tank fills with water from the supply line up to a preset water line.
  • When the flush handle or button is pushed, the flush valve at the bottom of the tank opens.
  • Water flows from the tank into the bowl via gravity. As the tank empties, it creates a siphon effect, pulling all the water out of the tank and into the bowl.
  • The siphoning action pulls water and waste out of the bowl through the trapway and into the drain pipe.
  • After the tank empties, the flush valve closes and the tank refills for the next flush.

The siphon effect created by the emptying tank is the sole driving force for flushing a gravity toilet.

Pressure-Assist Toilet Mechanics

A pressure-assisted toilet adds an air pressure component to significantly increase flush power beyond just gravity alone. Here is how a pressure-assist toilet achieves a high-powered flush:

  • As with a gravity-flush toilet, the tank fills with water up to a preset line from the supply line.
  • However, the tank is fully sealed, with only a small air pocket at the top. This air pocket is pressurized to around 25 psi.
  • When flushed, the pressurized air pocket pushes water out of the tank with immense force. This creates a strong siphon effect.
  • The high-velocity water entering the bowl scrubs the sides more aggressively, cleans waste off fully, and propels everything into the trapway.
  • The pressurized tank empties completely, ensuring no water is left clinging to the sides. This is more effective than the partial siphon created in a gravity tank.
  • As the tank refills between flushes, the air pocket repressurizes in preparation for the next high-powered flush.

In essence, the pressure-assist mechanism supercharges the siphon effect beyond just gravity to maximize flushing and cleaning power in the bowl.

Benefits of a Pressure-Assisted Toilet

Pressure-assisted toilets provide several noticeable benefits compared to gravity-flush toilets. Understanding these advantages can help you determine if choosing a pressure-assist model is the right decision for your bathroom.

Powerful Flush Cleans the Bowl Better

The pressurized flush created by a pressure-assisted toilet leads to significantly increased power and turbulence in the bowl. This extra energy scrubs the bowl more thoroughly and cleans waste off the sides more effectively.

With just gravity alone, a standard toilet often leaves hints of waste or toilet paper clinging to the bowl sides. The high-velocity pressurized flush of a pressure-assist toilet forces everything down the trapway without leaving any mess behind.

If you want commercial-style flushing power in a residential bathroom, a pressure-assisted toilet is the clear choice.

Effective for Removing Solid Waste

The robust siphon effect gives a pressure-assisted toilet excellent capabilities for removing solid waste and preventing clogs.

The full force of the pressurized tank emptying into the bowl takes every single waste particle along for the ride. This makes clogs much less likely compared to a standard gravity flush.

For bathrooms that get heavy usage or need to handle a lot of solid waste, a pressure-assisted toilet can work wonders to prevent clogs and keep everything flushing smoothly.

Uses Less Water Per Flush

Thanks to the jet-like siphon created by the outgoing pressurized air, pressure-assisted toilets can fully clean the bowl and flush all waste using significantly less water than a gravity-flush toilet.

Pressure-assist toilet designs typically have a flush volume of 1.0 to 1.6 gallons per flush (gpf), while most standard gravity toilets use 1.6 gpf or more. This water savings can add up to thousands of gallons per year for a busy bathroom.

For consumers concerned about conserving water, a pressure-assisted toilet provides a powerful flush with less water usage.

Reduces Risk of Leaks

The fully sealed tank with only a small air pocket minimizes places for leaks to occur on a pressure-assisted toilet. This contrasts with a gravity toilet tank that is mostly full of water all the time.

A pressurized tank also has no troublesome tank sweating during flushing that can lead to condensation-related leaks. The reduced risk of leaks helps contribute to the reputation of pressure-assist toilets as a durable and reliable option.

Good for Basements and Septic Systems

The increased flush power and clog resistance of a pressure-assisted toilet comes in handy for bathrooms located in basements or connected to septic systems.

For basements, the robust flush helps ensure that any waste will make it fully down the drain rather than clinging to pipes a few floors up. With septic systems, the reduced water usage per flush helps limit the amount of wastewater added to the septic tank. And the added power scrubs the pipes to limit clog buildup.

Overall, a pressure-assisted toilet is a practical choice for these types of special bathroom installations.

Wide Range of Design Options

While pressure-assisted toilets used to only come in utilitarian designs, many models today feature sleek contemporary styling with elegant curved profiles and smooth contours. All major toilet brands offer pressure-assist toilets in one-piece or two-piece configurations, various bowl shapes, multiple seat heights, and with slow-close seats and covers.

With the range of designs now available, it’s easy to find a pressure-assisted toilet that matches your bathroom’s decor and style.

Drawbacks and Considerations of Pressure-Assisted Toilets

Despite the performance benefits, pressure-assisted toilets do come with some disadvantages and compromises to factor into your decision.

Noisier Flush

The pressurized tank produces a louder flush compared to a gravity toilet. The whooshing air sound as the water exits the tank at high speed can be jarring in a quiet bathroom. Some users also report gurgling sounds coming from the toilet bowl after flushing.

If bathroom noise is a concern, or if you prefer a discreet flushing sound, a standard gravity toilet will be quieter than a pressure-assist design.

Higher Upfront Cost

The MSRP cost for a pressure-assisted toilet typically ranges from $350-$700, averaging around $500. This costs anywhere from $100-$300 more than a similarly featured gravity-flush toilet.

The added mechanical complexity does come at a price. Make sure the other benefits warrant the increased investment for your needs.

More Expensive Repairs

With more moving parts and sealed components, repairs on a pressure-assisted toilet will usually cost more compared to a non-pressurized gravity toilet. Replacing basic parts like the flush valve or flapper are often more labor-intensive jobs as well.

DIY repairs are typically not recommended on pressure-assist toilets. Most consumers will need to hire a professional plumber for any repairs, which also adds to the cost.

Risk of Pressure Imbalances

If the pressurized tank loses air over time or develops imbalances, it can interfere with the flushing power and cleaning performance. Keeping the ideal 25 psi air pressure consistently in the tank is essential. This requires proper maintenance and checking over the years.

Some consumers also report that a pressure difference between hot and cold water lines feeding the toilet supply can impact the pressurized tank and lead to issues. This typically only occurs in regions with very cold tap water rather than moderate ground temperatures.

Accessory Compatibility Limitations

With the unconventional tank design, many toilet accessories like drop-in cleaners and bowl treatments may not work effectively in a pressure-assisted toilet. Consumers will need to use only approved cleaning products and accessories made specifically for pressure-assisted models.

Some in-tank water saving devices that rely on adjusting the tank water level also may not be compatible. Check accessory packaging to ensure it is designed for use with pressure-assist toilets.

Leading Pressure-Assisted Toilet Brands and Models

Most major toilet manufacturers now include pressure-assisted models in their product lines. Here are some of the top pressure-assisted toilet brands and popular models to consider:


  • Kohler Highline: This classically styled 2-piece pressure-assist toilet is available in standard and comfort height options. Models with Kohler’s Class Five flushing technology provide 1.0/1.28 gpf high efficiency.
  • Kohler Cimarron: A more affordably priced pressure-assist toilet with modern curved styling and AquaPiston canister flush system. Provides 1.1/1.6 gpf water usage.
  • Kohler Wellworth: For a versatile pressure-assisted toilet with dual-flush options, the Wellworth offers 1.0/1.6 gpf flushing with classic Kohler reliability.

American Standard

  • American Standard VorMax: This powerful pressure-assist model comes in several configurations including ADA height and right-height options. Features a fully glazed 2-1/8″ trapway and 1.0/1.28 gpf water usage.
  • American Standard Champion 4: With a 4″ piston-action accelerator, this toilet delivers commercial-grade 1.6 gpf flushing power in a sleek, chair-height design. An excellent choice for heavy-traffic bathrooms.
  • American Standard Cadet Right Height: A reasonably priced model with pressure-assist flushing and an elongated right-height bowl design for easy usage. Provides 1.28 gpf water efficiency.


  • Toto Drake II Double Cyclone: This popular high-efficiency 1.28 gpf Toto model is available with a pressure-assisted double cyclone flushing system for maximum power and efficiency.
  • Toto Ultramax II: The Ultramax II pressure-assist model features a universal height and Toto’s ceFiONtect glaze to keep the bowl cleaner between flushes. Provides a commercial-grade 0.92/1.28 gpf flush.
  • Toto Eco Ultramax: Designed for high performance with low 1.28 gpf water usage, the Eco Ultramax pressure-assist toilet comes in classic elongated and round front bowl options.

Niagara Stealth

  • Niagara Stealth 0.8 GPF: Certified as the “World’s Most Efficient Toilet” by Maximum Performance Testing, this pressure-assist model only uses 0.8 gallons per flush but still cleans fully with a powerful flush.
  • Niagara Stealth 0.94 GPF: Similar ultra-high-efficiency performance as the 0.8 gpf model, with a slightly higher 0.94 gpf for increased waste removal capabilities.
  • Niagara 1.0 GPF: Niagara’s workhorse pressure-assist toilet provides robust 1.0 gpf flushing in a WaterSense certified high-efficiency design.

This covers a selection of some of the most highly rated and recommended pressure-assisted toilet models across top brands like Kohler, American Standard, Toto, and Niagara Stealth. Be sure to compare design features, bowl configurations, water usage, and pricing to select the right pressure-assist toilet for your bathroom needs and budget.

Pressure-Assisted Toilet vs Gravity Toilet Comparison

To help summarize the key differences, here is a comparison overview of pressure-assisted toilets versus standard gravity-flush toilets:

| Factor | Pressure-Assisted Toilet | Gravity Toilet |
| Flush Mechanism | Pressurized sealed tank creates an ultra-powerful siphon during flush | Relies on gravity to siphon flush water from tank to bowl |
| Bowl Cleaning Power | Jet-like flush leaves no mess behind for superior cleaning | May leave some hints of waste on bowl surfaces after flushing |
| Waste and Clog Removal | Evacuates solid waste completely with intense siphon action | Lower power may allow some waste buildup and clogs over time |
| Water Usage Per Flush | High-efficiency models available with 1.0 gpf or lower | Most models use 1.6 gpf or more per flush |
| Noise Level | Pressurized air produces loud whooshing sound during flush | Much quieter gravity flush |
| Repair Cost | Typically higher, often requires hiring a professional plumber | Lower cost for DIY fixes on gravity tank components |
| Purchase Price | $350-$700, around $100-$300 more than similar gravity toilets | Wide range usually $150-$400 |
| Accessory Compatibility | Limited, must be approved for pressurized tanks | Works with most standard tank accessories |

This comparison chart summarizes how the two toilet types differ in terms of flushing mechanism, performance, efficiency, noise, cost, repairs, and accessories. Keep these factors in mind as you determine whether a pressure-assisted or gravity-flush toilet is the better choice for your bathroom and needs.

FAQs About Pressure-Assisted Toilets

Q: Are pressure-assisted toilets better than gravity toilets?

Pressure-assisted toilets provide more flushing power and cleaner bowl results than a gravity toilet. However, they are also noisier, more expensive upfront, and cost more to repair. Choosing between a pressure-assist or gravity toilet depends on your priorities such as performance vs noise level, water savings, and environmental impact.

Q: Do pressure-assisted toilets clog less?

Yes, the intense siphon action of a pressure-assisted toilet does an excellent job of removing all waste and debris from the bowl. This significantly reduces the occurrence of clogs compared to a standard gravity-flush toilet.

Q: Why do pressure-assisted toilets have two flush options?

Most pressure-assisted toilets have a dual-flush feature with a lower water volume flush option (often around 1 gpf) for liquid waste, and a higher volume setting (around 1.6 gpf) for solid waste removal. This helps optimize water usage based on flush needs.

Q: How long do pressure-assisted toilets last?

On average, a pressure-assisted toilet will last around 15-20 years with proper maintenance. The sealed tank eliminates leaks and condensation that can lead to a shorter lifespan on a gravity toilet. However, repairs tend to be more complex on a pressure-assist toilet when needed.

Q: Do pressure-assisted toilets require special cleaning?

Pressure-assisted toilets typically need to use only approved tank cleaning products designed specifically for that type of tank and its internal components. Never use standard gravity toilet tank cleaners or drop-in tablets in a pressure-assisted toilet.

Q: Are pressure-assisted toilets ADA compliant?

Yes, many pressure-assisted toilet models comply fully with the Americans with Disabilities Act (ADA) requirements for accessible commercial and public bathrooms. This includes proper seat height, flush mechanism location, and lever operation to be ADA compliant.


Pressure-assisted toilets provide a number of appealing benefits, especially for residential applications that demand commercial-grade flushing performance to handle heavy usage and waste loads. Key advantages of pressure-assist toilets include increased bowl cleaning power, improved solid waste removal, reduced clogging, and lower water usage per flush compared to standard gravity models.

However, pressure-assisted toilets also come with some drawbacks to factor into the decision. The pressurized tank results in a louder flush and makes repairs more complex and expensive compared to non-pressurized gravity toilets. But the wide range of models now available from top brands allows finding a pressure-assist toilet in nearly any desired design, finish, and configuration.

Overall, understanding both the benefits and downsides will help determine if the boosted cleaning and flushing capabilities of a pressure-assisted toilet is the right solution for your bathroom needs and budget.