The nuclear track microfilters (NTMFs), a kind of novel material used in various fields such as precise separation of biological cells, filtering polluted air streams, stabilizing beverages, microelectronics, pharmaceutical, waste water recycling etc. have been successfully developed. These filters have been prepared by exposing polyester (polyethyleneterephthalate) films in ion accelerator (Si-28 ion of 120 MeV energy) and subsequently employing chemical etching process to enlarge the radiation damage in order to produce the 'through hole'. Various methods have been applied for the improvement of etch track rate of Si-28 ion beam. Also, a new sensibilization procedure has been developed for improvement of track etch rate. By this method, the NTMFs were developed having pore diameter varying from 0.4 to 1.4 mu m. The pore sizes were characterized with scanning electron microscope (SEM). The efficiency of these NTMFs in removal of bacteria from water was studied. The preliminary results show that these filters (0.4 mu m) are effective in removing up to 94% of bacteria from contaminated water.