The nanoscale silver-based disinfection of water is a proven technology. However, the lack of an affordable and easy-to-use system for controlled and sustained release of silver ions into the water has hindered its mass deployment in the field. The present work addresses this critical issue by developing a film-forming composite that can release silver ions at a controlled and sustained rate. The paper also demonstrates the application of the composite film to disinfect water taking Escherichia coli MTCC 443 as the model microorganism. The composite is fabricated by eco-friendly materials such as chitosan, reduced graphene oxide, silver nanoparticles, and tannic acid as feedstock. The hydraulically stable composite can either be used as a stand-alone antibacterial strip or can be coated on a suitable solid surface such as a mud-pot, sand particles or a specially designed reactor to create a point-of-use disinfection system. The composite film is reusable and can consistently produce 3 log reduction of microbes over several cycles. The conservative estimates show that the technology can provide microbial free water at the cost of < 0.5 USD per 1000 L. The composite may find applications in rural areas and urban slums where access to treated water is limited. © 2020 Institution of Chemical Engineers