Certain types of automated medical analysis equipment are used to analyze blood or other fluids. The equipment may thus use various diluents or reagents that allow the blood or other fluids to be run through the analysis equipment for analysis and data collection. Disclosed is a diluent preparation module that combines purified water and reagent concentrate for use by this equipment. Also disclosed is a diluent preparation unit that combines more than one diluent preparation modules for redundancy and back-up purposes. Also disclosed are systems for supplying the Diluent prepared by the diluent preparation module or diluent preparation unit to one or more analytic instruments.