I agree and caution needs to be used with any water heating system which stores water. We had an airsource heat pump system in the U.K. which ran our heating and hot water . It could only heat the water to 54C which was fine but the installers warned us not to change the settings on the immersion system . It’s not about the potability of the water it’s that legionnella is known to breed in water tanks. The immersion heater was installed as a backup and more specifically to run a preset programme once a week at 65C. There was a notice in red on the tank which said on no account must the programme be overridden as it was needed to protect against legionella bacteria and the immersion switches all had warnings on that they mustn’t be altered .
60°C will kill legionella in about 2 minutes.
55°C will kill legionella in about 2 hours.
It won’t actually grow above about 50°C
Ideally an air sourced system would control an immersion heater and do a pasteurisation cycle heating the water to 60 once a day - mine doesn’t although the reason might be that the system will go to a flow temp of 60° - it’s just woefully inefficient if you do. The installer had the hot water way too cool (52 I think) - I set it to 65 and the system promptly went into a sulk 
I now compromise on 56 and flow of 58, not great but probably the best compromise I can manage.
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