A washing machine includes a first washing compartment to hold a first set of articles to be washed and a second washing compartment to holds a second set of articles to be washed, the second washing compartment having an inserted position and a removed position. A liquid flow valve is configured to connect to an external liquid source to selectively control flow of liquid from the external liquid source and into one or more of the first washing compartment and the second washing compartment. An electric motor is configured to rotate the first washing compartment, and the second washing compartment, when the second washing compartment is in the inserted position. A controller, in communication with the electric motor, determines a mass of the second set of articles and then determines, as a function of the determined mass, a volume of water to be added to the second washing compartment.