Abstract: A device is provided for dissolving dry detergent to provide a liquid detergent solution to washing machines in a laundry. A tank is divided into upper and lower compartments. The upper compartment drains into the lower compartment when a tank valve therebetween is opened, and the compartments are maintained in mutual isolation when the tank valve is closed. High and low liquid level sensors in the upper compartment control mixing and dispensation of detergent solution. A quantity of dry, solid powdered detergent is mixed with a predetermined quantity of water in the upper compartment while the upper and lower compartments are isolated from each other during a mixing cycle. During the mixing cycle the lower compartment serves as a reservoir for supplying liquid detergent solution to one or more washing machines. Following the mixing cycle, the contents of the upper compartment are allowed to drain into the lower compartment.