Human adenovirus species C (HAdV-C) is frequently detected in China and worldwide. For the first time, 16 HAdV-C strains were isolated from sewage water (14 strains) and hospitalised children with diarrhoea (2 strains,) in Tianjin, China. Nearly complete genome data were successfully obtained for these viruses. Subsequently, genomic and bioinformatics analyses of the 16 HAdV-C strains were performed. A phylogenetic tree of the complete HAdV-C genome divided these strains into three types: HAdV-C1, HAdV-C2, HAdV-C5. Phylogenetic analysis based on the fiber gene showed similar outcomes to analyses of the hexon gene and complete HAdV-C genomes, whereas the penton gene sequences showed more variation than previously reported. Furthermore, analysis of the whole-genome sequencing revealed seven recombination patterns transmitted in Tianjin, of which at least four patterns have not been previously reported. However, the penton base gene sequences of the HAdV-C species had significantly lower heterogeneity than those of the hexon and fiber gene sequences of recombinant isolates; that is, many strains were distinct in origin, but shared hexon and fiber genes. These data illustrate the importance of frequent recombination in the complexity of the HAdV-C epidemic in Tianjin, thus emphasising the necessity for HAdV-C sewage and virological monitoring in China.