There have ben vacuums that filter with water (such as the Rexair/Rainbow) since at least the 1930s. While most of those quite heavy duty and powerful, they al

There have ben vacuums that filter with water (such as the Rexair/Rainbow) since at least the 1930s. While most of those quite heavy duty and powerful, they almost all suffered from indoor air quality issues, although I believe the newer ones do feature HEPA filters.