Finally got around to reading this paper “Drinking water microbiology – from measurement to management”. Seems like the number of culture-independent studies on drinking water keeps going up, it’s been a popular blog topic here in the last year. This review paper does a good job of summarizing the current state of knowledge, even including the more hypothetical bits such as drinking water probiotics.
My personal favorite part about this paper is the focus on research opportunities and gaps in our current knowledge. This paragraph in particular I think could be expanded well beyond drinking water to microbiology of the built environment in general:
A sobering question is how the wealth of microbial data acquired with state-of-the-art methods actually benefits DW management and whether microbial resource management concepts  are applicable to DW systems. The fact is that decisions at all stages of DW treatment and distribution profoundly shape the microbiome. While this provides ample opportunities to purposefully manage DW microbiology, it also highlights the need for a multidimensional approach toward studying these systems and proposing management solutions.