John, this is not the best video on Distilled water, but I found it very useful. https://www.youtube.com/watch?v=qTtMDbMYnGM
I believe the distilled water acidity comes from CO2 in the carbon filter, or some acids taken up from the air or pipes, which precipitate the distilled water vapor. Good thing is actually, that the body transforms the CO2 in bicarbonate ions HCO3- which are alkaline or gets rid of it by exhaling.