[malfist]

I don't know where you're getting your science from, but seltzer water is not dehydrating, and distilled water is not undrinkable for humans.

At best you can say that if you consume exclusively distilled water for a long time, you might deplete your body of some minerals unless they are replenished another way.

[flavius29663]

I didn't mean it as a direct consequence. Seltzer water will de-hydrate people that have bladder sensitivity to acids (like myself).

Also, the purpose of the " in the "undrinkable" statement was to make it clearer that it's about people considering it "undrinkable", not that it's toxic or it doesn't hydrate. You just wouldn't drink distilled water unless you were dying of thirst in the desert.