In this work, we present polymeric nanocomposites as valid systems for water treatment. This new class of materials has attracted extensive attention in the recent years in several fields of science and technology, because they join structural flexibility and relatively simple processing of the polymers with the properties of the nanomaterials, such as the photocatalytic activity of TiO2. We hence embedded in PMMA titanium dioxide nanotubes, synthesized by electrochemical anodization, obtaining very cheap materials for water purification. We realized these polymeric nanocomposites by sonication and solution casting method, and we evaluated their photocatalytic activity by the bleaching of Methylene Blue (MB) dye in aqueous medium. We also tested the antibacterial activity through CFU (Colony Forming Units) count using Escherichia coli as a model organism.