I have an RO/DI (reverse osmosis/deionization) filter to "make" pure water (0 TDS) for aquarium use. For a while, I read about how dangerous it was to drink it. People made it seem like if I drank one glass, I would end up in the hospital. None of it really seem substantiated so I gave it a whirl. I didn't drink JUST that but when I was home, I did. I noticed no ill affect but I can tell you in quenches ZERO thirst. And I mean none. I stopped after a little while because this guy is right...it's just flat with no taste.