Emergency Services

Gravity vs Pressure-Assisted Toilets

Ever spent a lot of time thinking about your toilet’s flushing mechanism? Probably not. Nevertheless, you may need to know how it works and the difference between the two types that are offered in order 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.


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.


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.

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 are becoming more popular and if you’re considering opening a new business, it’s important that you know the advantages.


  • Cheaper
  • Easy to repair
  • Easy to find parts for
  • Easy to clean
  • Excellent for home use


  • More expensive
  • Higher flushing power
  • Excellent for office or industrial use
  • Difficult to repair
  • Difficult to find parts for

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.

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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340 W 500 N
North Salt Lake, UT 84054
United States