You need to educate yourself a little more than what you get off of the internet. You are trying to reason with too little understanding of the whole subject matter. You come off as sounding kinda smart, I'll give you that, but that's just sounding smart...not actually BEING smart. Wikipedia isn't a substitute for years of education and experience. Keep up the show for the others that are entertained here, but your circle of failed logic looks like the juggling act of a circus clown.
I don't know much about "smart", but I s'pose us ignorami should just take the word of some un-credentialed anonymous web-poster (on the internet no less) who seems to prefer silly insults to citing reference when others disagree. Thanks for setting us straight on that.
If you need the raw data of actual biologists and the investigative findings of public health researcher chasing actual cases, there are troves of real science available on the web. I've reviewed this topic multiple times in multiple contexts, reviewed quite a few published scientific documents available on the NIH website and other credible over the past couple of decades. If you can point me to a credible source that can correct or update my recollections on the where the growth risk temperature zones are, or new information on how new colonies can get established and grow in tanks that are allowed to stagnate at room temp, I'm interested.
The very reason 140F has been established as a mandated storage temp under plumbing codes (and tempering of hot water coming out of those tanks to protect against scalds) comes from decades of evidence that 140F storage temps does indeed kill legionella and that 120F water does not. Storing water at 120F won't kill legionella, or reduce the size of already established colonies, but that legionella colonies won't increase at that storage temp. (Need sources for that?)
I recall reading about a case at a medical facility in the Netherlands in the late 1900s, or maybe shortly after Y2K where the legionella outbreak was traced to COLD water distribution plumbing, where a section of the cold water distribution plumbing ran along side the heating system plumbing between floors in a plumbing chase, and that section of pipe regularly stagnated to about 100F every weekend when no cold water was being drawn. The investigators determined that the repeatd stagnation in the high-growth temperature zone allowed legionella biofilms to get established in that section of plumbing. (The article is probably still available on line, but it's in Dutch- jammer he'?) That's a typical scenario of real world cases- chronic stagnation at an optimally bad temperature.
I've looked for (but have yet to find) any cases in the literature where hot water storage tanks normally kept at 120F+ temps allowed to stagnate at
room temp developed legionella colonies. Once these colonies get established it takes 140F or hotter temps to kill them, but generally speaking, the places they get going easily are where they stagnate in the 85-110F zone. Simply passing through that temperature for a few hours several times per year, with storage temps at 140F before & after the periods where the temperature slewed through the danger zone doesn't have much risk- you're killing off any legionella introduced to the tank during active heating periods, and letting it stagnate in the off periods to well below where the colonies can grow. Call that logic a juggling circus clown act if you like, but when you do, show me a documented case (even one) where that has actually happened. Of the dozens of actual documented cases I've looked at previously, none fit the profile.
I'm neither a medical nor pubic health professional, but I probably dig up and read more medical, scientific, & technical source literature on topics I'm interested in than the average hack. (I'm not a fan of Wikipedia- often the referenced sources in the footnotes on Wikipedia are from credible sources, but often not.) I'm all for educating myself- rather than making bald assertions & inane insults, cite sources. Your word alone really isn't worth much, given that your level of discussion rarely strays from the "cute quips and sassy witticisms but actually contribute nothing" you accuse others of.