Abstract: An antimicrobial composite includes a polymeric support and at least one transition metal mounted onto the support surface. The transition metal may be silver, and the support material may be a non-reactive plastic such as polyethylene or polypropylene. The composite may be encapsulated by a permeable or porous outer layer. Preparation of the composite may involve mixing an aqueous salt solution containing the transition metal with the support in the presence of a surfactant, precipitating the metal onto the support, and reducing the metal to its elemental state. The resulting composite in which the polymeric support surface includes the elemental metal is useful in the treatment of water and ice to inhibit or prevent microbial growth.