Sanitary environments that undergo frequent cleaning and disinfection may harbor microbial communities with potential health risks. While biofilms in healthcare settings are well studied, comparatively less is known about sink-drain microbiomes in public and educational buildings, where hundreds of people may interact with shared sink fixtures. This study characterized the spatial and temporal heterogeneity of sink-drain biofilm microbiomes in academic buildings. We sampled 16 sinks from two bui