Distilled water is okay. KYHillChick has been running a distiller since her cancer surgery in 2018. She was put on distilled water by her nutritionist.
Yes, I'd always heard distilled water is bad, that it sucks minerals out of your body. However, if you're doing it short term there is no problem. KYHillChick takes a bunch of supplements every day, partly to put back what the distilled water might take out.
Rainwater is a whole 'nuther matter. It too is safe, but it's got stuff in it. One thing I know of for sure is oxygen. My water system at the farm runs off rainwater. I had to replace the pump after 3 years, because the water ate the steel impeller. I put in a pump with a plastic impeller, and it's been good for over 15 years. Rainwater also absorbs all the air pollutants. Where I am out in the sticks, it's fine. However, I would not want to drink rain from just downwind of Cincinnati.
