It was of interest to investigate the use of graphene as both an antibacterial agent and an absorbent to treat drinking water. The use of l-ascorbic acid as a reducing and capping agent was developed as a novel method for the immobilisation of the graphene-copper composite. Graphene oxide (GO), reduced graphene oxide (rGO) and a graphene copper composite (Cu-rGO) were produced and characterised using ultraviolet-visible spectroscopy (UV-vis), thermogravimetric analysis (TGA), dynamic light scattering (DLS), scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDX). Graphene oxide (GO) and reduced graphene oxide (rGO) showed no antibacterial activity. The graphene-copper composite showed antibacterial activity against E. coli and B. subtilis at 105CFU/ml at 100ppm. Scanning electron microscopy (SEM) showed membrane damage as the most likely mechanism of antibacterial action and fluorescent microscopy showed adherence of bacterial cells to graphene particles. The effectiveness of the composite was attributed to the antibacterial activity of the copper and the adsorptive potential of the graphene. Immobilisation of the composite was of interest to apply the material in a practical manner to a water treatment prototype. Two methods, one using sodium borohydride (NaBH4) and another using l-ascorbic acid were used for composite production. The composite was immobilised as free standing films and as a coating on commercial glass fibre membranes. The immobilised composite inhibited E. coli and B. subtilis at 108 CFU/ml within forty minutes of contact and had maximum adsorption capacities of 482 mg/g and 183 mg/g for methylene blue and famotidine respectively. A prototype incorporating the composite coated membranes was capable of inactivating E. coli at 102 CFU/ml and removing Cryptosporidium at 10 oocysts/L at a flow rate of 90 ml/min. Testing following the filtration of 100L showed that copper leaching was minimal with a maximum concentration of 1.3mg/L and no mutagenic activity was detected using the AMES test.