Abstract: A combination wash basin and toilet water conservation system having at least one wash basin and a toilet having a water tank. The water tank has a fresh water chamber and a gray water chamber. A first outlet connects the gray water chamber with the bowl of the toilet and a flapper valve closes this outlet. A second outlet connects the fresh water chamber and the gray water chamber and a buoyant valve closes this outlet. Piping connects the drain of the wash basin to the gray water chamber. Piping also connects a source of fresh water to the fresh water chamber. A hand lever on the outside of the toilet operates a lever arm within the water tank which when it is raised upwardly actuates structure causing the buoyant valve to rise thereby letting fresh water into the gray water tank. Structure is also actuated in the gray water tank when the lever arm raises upwardly and this structure opens the flapper valve to release water from the gray water chamber into the toilet bowl for flushing thereof.