Toilet Flush Types

Pressure-Assist
These models use high water pressure to forcefully remove waste from the bowl. Pressure-assist models offer unsurpassed flushing power, routinely achieving the highest MaP scores. The drawback to pressure assist models is that they are often loud, which can lead to noise problems in small homes and apartments, especially when bedrooms are located adjacent to the bathroom. Pressure-assist models require a minimum municipal water pressure of 25 psi and are generally more expensive than other types of toilets. A cost range of $225 to $300 is typical.1

Vacuum-Assist
These models use a vacuum in the tank to pull air out of the trap below the bowl, helping quickly evacuate waste. Flushing performance is widely variable, depending on the quality and engineering of the individual product. Vacuum-assist models are generally as quiet as normal gravity assist toilets, making them a better choice in situations where noise is a concern. A cost range of $225 to $300 is typical.2

Gravity Assist
This is the technology in the typical residential toilet. These models rely on the force of water dropping from the tank to remove waste. Their familiarity makes maintenance easy and noise is generally not a concern. They can be used in situations where municipal water pressure is as low as 10 psi. Some models may equal pressure-assist toilets in terms of flushing power, but usually cost just as much. Many cheaper models may not provide adequate performance. In general, however, increased cost does not guarantee better performance. A cost range of $150 to $300 is typical.3

Dual Flush
A dual flush toilet is a toilet that allows different volumes of water to be used depending on the type of waste. These are increasingly popular because they reduce water use for disposing liquid waste, while maintaining the ability to flush solid wastes with a larger volume of water. A cost range of $225 to $350 is typical.4

1 "Toilets: Comfortable and Efficient." ConsumerReports.org Web site. Jan 2008. Consumer Reports. 21 Jul 2008. www.consumerreports.org/cro/home-garden/bed-bath/bathroom-remodeling/toilets/toilets-805/overview/.
2 ibid.
3 ibid.
4 Survey of "dual flush toilets" on www.google.com/products, July 2008.