I agree that most distilled water I probably low risk, if bottled under sterile conditions. I use .2 micron filtered water because a filter that fine traps any mycobacteria.

I personally think there is a difference between steam from boiling water, which is highly unlikely to be contaminated, and "steam" from a shower, which is droplets water that is not hot enough to kill NTM. But I don't have any science to prove it.

I just think we get "way in the weeds" sometimes trying to avoid EVERY exposure. I try to concentrate on reducing big risks (eg indoor pools and hot tubs) and ignoring the small ones (getting my hair washed at the salon or opening the dishwasher that has run at 180⁰ for an hour.) I have been MAC free for 5 years and counting after almost 2 years of antibiotics.

Everyone is different and I respect that. My risk tolerance is probably higher than average in this group.