Emergency Services

Gravity vs Pressure-Assisted Toilets

Ever spent a lot of time thinking about your toilet’s flushing mechanism? Probably not. As the world changes, more consumers are basing their purchasing decisions on ethics. The choice springs from cost-effectiveness, which mechanism is better for their homes, and even which type saves on water. Nevertheless, you may need to know how flushing mechanisms work and the difference between the two types that are offered to understand how to troubleshoot and repair your toilet. Whether you prefer gravity-assisted or pressure-assisted flushing mechanisms, here are the pros and cons of each, including how they work. Need help installing one or the other? Call us today!

When it comes down to it, there’s one thing to keep in mind. Both gravity or pressure-assisted toilets can be low-flow systems. With a low-flow system, you’re automatically going to save on water and expenses over time. The only question is if your home has the proper plumbing to support a low-flow toilet. All that aside, let’s dig into what a gravity-assisted toilet is all about. 


These toilets are the most common variety and have been for a long time. Gravity-assisted toilets function through gravity, as their name implies. When you push the handle, a valve opens within the tank and the water falls from the force of gravity. As the water falls inside the bowl a siphoning effect is created in the trapway at the base of the toilet. This siphoning action moves water and waste through the pipe and into the septic tank or utility sewer pipes. Following this gravity-induced waste and water removal, a small gushing pipe refills the tank until a float shuts off the flow of water. To prevent overflow in the tank, there is also a small overflow tube to keep the water inside the tank.


Most homes can accommodate a gravity-assisted toilet. When it comes to a low-flow gravity-assisted toilet, you may run into a few issues, however. While a home’s plumbing structure can interfere with installation, that’s not the only concern. It’s widely observed that low-flow toilets don’t always flush waste as efficiently. Even though you may be saving on how much water you’re using per flush, a second or even third flush may be needed to dispose of the waste. 


Pressure-assisted toilets rely on the same gravity but assist the force of gravity with additional pressure. A small tank within the main tank supplies added pressure. This is achieved as water displaces air within a sealed cylindrical tank inside the larger ceramic tank. This cylinder is metal or plastic and helps to generate a larger force through air inside the cylinder. Flushing these toilets produces a loud whooshing sound characteristic of the air pressure being forced through the tank. These toilets hold more water and require a minimum water pressure of about 25 PSI to operate most effectively and are becoming more popular as efficient toilets that can use less water and flush more efficiently.


A low-flow pressure-assisted toilet seems to be a bit trickier to install in homes. Most homes built since the early 2000s have no problem accommodating this type of toilet. Homes older than a couple of decades may need to have a few plumbing adjustments for these low-flow pressure-assisted toilets to function properly. It may be worth the investment, however, because many low-flow toilets with a pressure-assisted function can last up to 30 years! This also means that throughout that time a homeowner can save up to $3.5k on water bills alone! 

Advantages and Disadvantages

Gravity-assisted toilets have been around longer than pressure-assisted so you may see them more frequently in your everyday life. However, pressure-assisted activities are becoming more popular and if you’re considering opening a new business, you must know the advantages.


  • Cheaper
  • Easy to repair
  • Easy to find parts for
  • Easy to clean
  • Most popular
  • Clogs easier
  • May need multiple flushes to dispose of waste
  • Excellent for home use


  • More expensive
  • Higher flushing power
  • Excellent for office or industrial use
  • Needs to generate pressure to operate
  • Loud
  • More resistant to clogs
  • Difficult to repair
  • Difficult to find parts for

What it all comes down to is personal preference. While pressure-assisted toilets seem to be more expensive, over time you will end up saving money. Gravity-assisted toilets are the most popular and most economical options as they are cheap and effective. In general, gravity toilets are more than sufficient to meet the needs of most household and commercial settings but can be less than optimal in terms of sheer volume efficiency than pressure-assisted varieties. For larger-scale plumbing needs, pressure-assisted toilets may be optimal. And remember, you always have the option of choosing a low-flow toilet. It all depends on the investment you’re willing to make in restructuring your plumbing system (in older homes only).

Whichever toilet you decide is best for your needs, Shamrock Plumbing is prepared to help you install, maintain, and repair it. Don’t hesitate to give us a call at 801-505-9505!


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