Graphene, a single sheet of carbon atoms, has a key role for the manufacture of innovative membranes for water purification and desalination. The aim of this work is to show the vast potential of monolayer graphene and its multi-layer declinations (BLG bilayer graphene, TLG trilayer graphene) in wastewater treatment. The intrinsic defects, present in the graphene layer due to its growth, and the extrinsic defects, induced by the transfer process on porous polycarbonate membranes (PCTE), form leakage pathways that can be successfully used in the rejection of NaCl for desalination applications or for the removal of different pollutant molecules in aqueous solutions.