The removal of bacteria and other pathogenic micro-organisms from drinking water is usually carried out by boiling; however, when this is not a feasible option, a combination of treatment based on filtration and disinfection is recommended. In this work, we produced cellulose filters grafted with silver nanoparticles (AgNPs) and silver nanowires (AgNWs) by covalent attachment of separately prepared Ag nanostructures on thiol- and amine-modified commercially available cellulosic filters. Results obtained from scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), and energy-dispersive X-ray spectroscopy (EDS) all revealed that such modified cellulose membranes contained large amounts of homogeneously dispersed AgNPs, whereas X-ray photoelectron spectroscopy (XPS) analysis demonstrated that the aforementioned nanostructures were immobilized on the membrane with a strong and stable covalent bond between the thiol or amine groups and the surface of the Ag nanofillers. This durable and robust covalent attachment facilitated outstanding suppression of the uncontrolled release of the nanostructures from the membranes, even under strong ultrasonication. Those membranes also demonstrated high permeance and antimicrobial activity in excess of 99.9% growth inhibition against Escherichia coli, which was used as a model of gram-negative coliform bacteria. Bacteria percolated throughout the tortuous silver-loaded filters, thus increasing the chances of contact between the Ag nanostructures (wires or nanoparticles) and the passing bacteria. Thus, we anticipate that these filters, with their high antibacterial activity and robustness, can be produced in a cost-effective manner and that they would be capable of producing affordable, clean, and safe drinking water in a short period of time without producing an uncontrolled silver release into the percolated water.