This paper describes an alternative, patented, non-chemical cooling water treatment system that has proven to be effective in controlling/eradicating bacteria and Legionella. The technology works primarily on the principals of Controlled Hydrodynamic Cavitation (CHC). The VRTX system eradicates bacteria by a combination of four synergistic actions: pressure, vacuum, kinetic impact and sheer force at the collision point. Within the chamber the following are generated: hydrodynamic cavitation, sonic waves and oxidizing chemicals (hydroxyl radicals). In this paper, field test results will be presented to demonstrate the effectiveness of VRTX system in controlling bacteria and Legionella in cooling water systems. Testing was conducted at a cooling tower of a Spanish hospital. Comparisons were made between their current chemical treatment, combined chemical (one half the normal dose) along with VRTX and VRTX treatment alone. The results indicated a significant improvement of the partial checmical/VRTX treatment over chemicals only. Data on water savings, improved heat transfer, effects on calcium removal, and cost advantages will also be presented.