Legionella won’t make you sick if you drink it, only if you breathe it in. It exists in clean drinkable water all over the world. It’s capable of hibernation and able to survive without nutrients for long periods. So it’s at least a potential risk any time you breathe aerosolized particles from water that is not hot enough to kill it. Any type of water heater that heats to 60 degrees Celsius will kill it.

This is a great idea if you are the only one using your shower. If you have 4 family members, each of whom likes a different shower temperature, it is less ideal. I think controls that allow separate on/off and hot/cold dimensions are best for most scenarios.

This map is apparently from Wikipedia, and is based on a 1995 CIA ethnolinguistic map. The version here is identified as from 2007, with some changes made by wikipedia commons editors (visible changes in Abkhazia and other places). The changes are marked as disputed and unsourced, and it does seem like someone took the letters marking general presence of an ethnolinguistic group (indicating sporadic presence) from the 1995 map and converted those letters into solid bands. This does seem to be a dubious change, as I cannot find any support for this solid separation of groups in Abkhazia and elsewhere.