The supply of safe drinking water in buildings, from source to tap, is of paramount importance to public health. Premise plumbing is the portion of drinking water distribution systems (DWDS) beyond the service pipe. The plumbing is located within buildings and can be characterised by warm conditions, low water flows, poor levels of residual disinfectants, and high surface area to volume ratios. Consequently, these conditions may favour microbial growth, in both the flowing water and within biofilms on the pipe surfaces, constituting the drinking water (DW) microbiome.
It is estimated that only 5% of microbial growth within premise plumbing systems are in the bulk water, with the majority of biomass existing as biofilms. Furthermore, these DW biofilms have been implicated as the infectious source, supporting the complex ecology, persistence and increased pathogenicity of waterborne opportunistic pathogens like Legionella pneumophila. Such opportunistic pathogens may be transmitted through contaminated aerosols released by DWDS outlets to downstream users and susceptible individuals, leading to severe health implications. Thus, there is an urgent need to improve our understanding of the drinking water (DW) microbiome, to support the design of novel control strategies to remove opportunistic pathogens in these environments.
In this study, we characterised the DW microbiome of the 50 year-old Frank White Building at the University of Queensland, which was demolished in late June 2018. Prior to demolition, bulk water samples and a total of 15 m of ¾-inch copper pipes containing mature DW biofilms were obtained. The pipe was sectioned into 1 m lengths and DW biofilm and water sample communities were characterised using culture-dependent and culture-independent methods. Next generation sequencing (NGS) was used to assess bacterial, archaeal and protozoan community dynamics to evaluate the DW microbiome, and the implications of these findings are discussed. To our knowledge, this is the first comprehensive evaluation of such a length of plumbing biofilms and the findings shed light on and the complex ecology of DW microorganisms and various opportunistic pathogens.