Abstract: An apparatus and method for controlling the amount and concentration of make-up water and chemicals introduce into the recirculating water of a cooling tower system. A float operated make-up valve controls the addition of make-up water to the tower. As make-up water is added to the tower a vacuum is produced at an injector valve which draws chemicals from a chemical holding tank into the make-up water, thereby allowing precise control of the chemical concentration in the make-up liquid. Further, a bleed valve is provided which is responsive to the vacuum produced at the injector valve and bleeds a portion of the recirculating water to waste.