Abstract: A vacuum power booster with automatic waste liquid discharge for a water vacuum extraction apparatus. A first vacuum source is coupled to a first waste liquid storage tank in a main housing, typically vehicle mounted. A second, auxilliary vacuum source is mounted in a mobile housing remotely located from the first housing which contains a second auxilliary waste liquid storage tank. A vacuum pickup implement is coupled to the mobile waste liquid storage tank for extracting and transmitting dirty liquid from the surface being cleaned to the second waste liquid storage tank. The liquid in the second waste liquid storage tank is automatically discharged and transmitted to the first waste liquid storage tank when the level of such liquid reaches a predetermined height or level within the second waste liquid storage tank.