Most vacuum cleaners trap dust and dirt inside a vacuum or dust bag. Instead of using a vacuum bag the Rainbow uses water to trap dirt and dust. There is a pan or reservoir of water inside Rainbow vacuum cleaners which is emptied after use. It is quite a unique vacuum cleaner. Rexair says there system works best because, most dirt particles contain an electrical charge that is opposite from the electrical charge of water.
Opposites attract and thus the dirt and dust is trapped in the water.
Rexair - Rainbow Vacuum Cleaner History Rexair history goes back about 80 years. John W. Newcombe invented a machine called the Separator. This machine was made to separate dust and other material from the air. In 1926, Leslie H. Green became noticed the Separator and thought it could be applied for home use. Green and Newcombe joined forces and created the first bagless cleaner in 1927.