I am using Walgreens distilled. No fluoride, although they had that kind. The conductivity reading was 1.7 before I made it. I just tested the water again and it still reads 1.7. The water by itself tastes okay, but not as good as distilled in a bottle. If I boil some of my RO water which has a conductivity reading of about 20, will that bring it down? Otherwise maybe I can find a glass bottled source and try that. What do you think? I gave some to my 82 year old dad because he has a sore throat (he has emphysema), so I hope it isn't dangerous. But, use bitter as a search word on this forum. It seems that a lot of people end up with bitter tasting CS. Weird.