Abstract: An open-loop ozone washing system for safely washing with high levels of ozone is shown and described. In one embodiment, the system includes at least one washer having a drain in fluid communication with a sewer. The system also includes an ozone source, which is preferably an ozone generator. The system also includes an off-gas control system operably connected to at least one washer. Using such a configuration, the washer can safely wash with a liquid wash bath having about 2 ppm to about 20 ppm ozone. The present invention also includes kits and methods for converting traditional washing machines to open-loop ozone washing machines.