Just came across this article entitled “Rainwater harvesting tanks enable spread of dangerous pathogens, study shows”. The article describes a fairly straightforward set of findings from rainwater storage tanks in South Africa. Researchers found Legionella, Klebsiella, Giardia, Salmonella, and Yersinia. Not a friendly-sounding list of bugs.
However, I have the usual set of issues with this. Firstly, there are plenty of species/strains in all these taxa that are totally harmless… so we don’t know much beyond the *potential* for pathogens in the system. Secondly, the claims from the title are clearly overblown, simply finding these taxa in the tanks doesn’t mean that the tanks are “enabling the spread of dangerous pathogens”.
I’d look for more detail in the actual research article but the link takes to a closely related paper on E.coli in rainwater by the same group and I haven’t found the correct source paper yet.
Also missing is a discussion of the tradeoffs between drinking this potentially contaminated rainwater from storage and drinking untreated water from potentially much worse sources.