I wonder if pure H2O is even possible through any means. Even distilled water probably has some dissolved CO2 and O2 at least, plus trace material from the still, spout, and container the water was stored in after being condensed. Also residue from the last time it was all rinsed (traces of whatever was dissolved into that water) and anything that was airborne that might have drifted into the water, including airborne microbes, spores, and other dust.
also, tablesalt usually has at least some significant percentage potassium chloride, which tastes like sodium chloride, but is MUCH less terrible for your body.
Source: am geoscientist. Licking rocks is one of our university trained skills. I kid not.
Tangent: we printed these t-shirts in undergrad that said "You know you're a geologist when you can say with a straight face: have you tried licking it?"
Are there any dangerous ones? Like, "this is either slate or megamurderstone. You can tell the difference because the latter tastes more tangy and then you melt from the inside"?