Cooling towers are heat rejection systems that are used in some industrial applications, and they have the potential to develop infectious concentrations of Legionella pneumophila. SANIPACKING (R) cooling tower fill material and standard polypropylene fill material were compared in terms of biofilm formation potential and anti-Legionella activity within a 4-month period using a laboratory-scale recirculating water system. The recirculating water system was experimentally infected with a L. pneumophila standard strain (ATCC 33152) suspension and operated continuously until all experiments had been completed. Results showed that the L. pneumophila rapidly multiplied in a short time during the study within the model system bulk water. No L. pneumophila was isolated from the SANIPACKING (R) surface during the 4-month period, whereas intensive colonization occurred on the standard polypropylene material surface in the first month. Heterotrophic bacterial counts on the surfaces showed that a significantly low accumulation was recorded on the SANIPACKING (R) surface in comparison to the standard polypropylene material. Total bacterial counts on surfaces, determined by epifluorescence microscopy (using DAPI), revealed that significantly low counts of microorganisms colonized on the SANIPACKING (R) surface.