Unlike vacuum cleaners which collect dry dirt and debris, or robot mops which just push a dirty cleaning pad around your floor for a while, mop vacs (you may also see them called “vac mops” or “wet-dry vacuum cleaners”) suck up dirt and debris while also mopping hard floors with a constant supply of fresh water and cleaning solution. The fresh water comes from the machine’s fresh water tank and works with a rotating soft brush roller to mop the floor. In the same pass, the mop vac sucks the used water back into a separate dirty water tank where it filters out any solid debris. If the mop vac is any good, it should also leave your floors fairly dry.