A recent article1, ASHRAE guidelines, and the position of many health authorities point to the reality of the dangers inherent in systems populated with Legionella species. However, therein and in other publications, we find the mantra “The mere presence of Legionella . . . will not in itself cause illness. High numbers of Legionella have been noted in cooling towers and other sources with no associated disease” that serves to lessen the impact of the reality. This untenable position is also held by some water treatment firms, some at the Centers for Disease Control (CDC), and a few world health authorities (albeit not all). If numbers imply nothing, why test?

To everyone with a similar view, I pose the question: “If someone were to add live vibrio cholera to a 1,000-gal container at an inoculum <1 colony forming unit per million (cfu/ml), would that person take a drink of water from that tank?”