Definitely worth checking out this paper from Kyle Bibby’s lab: PLOS ONE: Shift in the Microbial Ecology of a Hospital Hot Water System following the Introduction of an On-Site Monochloramine Disinfection System. A key figure in the paper is Figure 2 which I post here.
The figure shows a PCA based clustering of samples based on the composition of the microbial communities in those samples. It shows quite clearly that there were major changes between the “before treatment” samples and the “after treatment” samples. The paper discusses this result and other results int he context of disinfection, hospitals, and microbial ecology of the built environment.