Textile fibers are widely used for fine filtration in the disposable cartridge filter market. In this work the filtration mechanism of threaded microfiber water filters was characterized by testing the effect of filtration velocity, slurry concentration, particles size distribution (PSD) and filter pore size and porosity, on the filter performance. Constant flow rate experiments were conducted with micronized CaCO3 slurry as a model substance. It was found that the predominant filtration mechanism of the studied filters is cake filtration. Very efficient filtration followed by effective automatic cleaning of the filter was obtained as indicated by complete removal of the CaCO3 particles in all the conditions studied and similar clean filter resistance over repetitive cycles. Shorter filtration cycles were obtained at higher velocities, low porosity filter and narrow PSD. Correspondingly, the filter capacity declined as the filtration cycles were shorter. Yet, the filter capacity was found to be independent of the CaCO3 slurry concentration. A criterion of specific consumed energy per unit filtrate volume (E-s) was developed. Analyses of the effect of the various studied parameters on E, revealed its dependence on the slurry concentration, velocity and filtration time.