An antimicrobial film-forming composition, an antimicrobial film, and a method of verifying the presence of an antimicrobial film. The film-forming composition can include no greater than 10 weight percent of polyvinyl alcohol, from 0.05 to 15 weight percent of polyhexamethylene biguanide, from 0.001 to 10 weight percent of a quaternary ammonium compound, and water or a water-based solvent. The film-forming composition can form a water-soluble, biocidal antimicrobial film that includes no greater than 98 weight percent of polyvinyl alcohol, and from 1 to 15 weight percent of each of polyhexamethylene biguanide and the quaternary ammonium compound. The method can include applying a film-forming composition comprising an indicator dye to a surface, drying the film-forming composition to form an antimicrobial film, and triggering the antimicrobial film to trigger the indicator dye to verify the presence of the film.