SWOOSH goes the toilet. What a surprise! Never saw or heard one flush like that before. And you were still sitting down – wow, what a thrill.
When the federal government required that all toilets use 1.6 gallons or less water per flush, several manufacturers developed pressurized flush toilets. We have all been surprised by the noise and velocity of the flush.
The toilet tank contains a plastic vessel that is pressurized by the building’s water pressure as it refills. The water also compresses air in the tank. When you press the flush lever, water leaves the tank under pressure with a resounding SWOOSH.
Recently, designers have greatly improved the standard flush toilet by raising the height of water in the tank, enlarging the flush valve, reducing the quantity of water in the trap and enlarging the diameter of the trap. These improvements make the 1.6-gallon flush toilets perform well without the aid of a pressurized tank.
While pressurized toilets are dramatic, we won’t see many in the future because of their cost and because the newly designed standard toilets now work well, unlike many of the original low-volume toilets.