One commercial contact chamber which is designed for ozone disinfection has been tested for the following : determination of residence time distribution (RTD), measurement of dissolved ozone concentrations in water, and measurement total plate counts. Disinfection is achieved but this type of reactor is not ideal, due to dispersion of the residence time distribution. As these bubble contactors do not behave like plug flow reactors, it is possible to improve the hydrodynamics of ozone contactors with the use of static mixers. Experiments with ozone static mixers have been conducted.