An investigation of microbiological potable water quality in high-rise residential buildings of Hong Kong

In Hong Kong, the potable water in residential buildings is generally supplied through water pipes and available at water taps in washrooms and kitchens. It is known that microbial growths in water supply systems are highly associated with enteric diseases. However, the information and guideline on the microbiological potable water qualities in Hong Kong is limited. This study aimed to investigate the microbiological potable water qualities in high-rise residential buildings. Tap water samples (100 mL) were collected at the water supply systems from residential buildings during summer of Hong Kong. The age of buildings of the sampling sites ranged from 5 to 48 years and located at both rural and urban areas. The results showed that the heterotrophic plate counts (HPC) bacteria ranged from 0 CFU mL−1 to 1.60 CFU mL−1. The identified bacterial genera in water were Acinetobacter, Aeromonas, Bacillus, Escherichia coli, Micrococcus, Pseudomonas, Staphylococcus and Streptococcus. And the fungal count ranged from 0 CFU mL−1 to 0.20 CFU mL−1. The identified fungal genera were Aspergillus, Penicillium and non-sporulating fungi. Future investigations regarding the possible association between the environmental factors and microorganisms in the potable water of high-rise residential buildings in sub-tropical climate as well as their health effects were recommended.