I’m no chemist, but it’s likely just deionized water. It can irritate your mouth and throat since the ion-dipole force in water makes it electrostatically attract ions, and can likely pull them from the cells on the surface of your mouth/throat. I don’t fully know if that’s the reason it would burn because I don’t remember how strong these forces actually are, but if I remember correctly it’s dependent on the ion and the difference in charge.
Pure water definitely will. A YouTuber did a video on it, and he tasted a very small amount. At first he didn't think there was a problem, but then he added to the end of the video to NOT do it because indeed, he burnt the crap out of his tongue with just the tiny amount he sampled.
We learned about this in grade 10 science class. You'll lose a layer of skin.
Maybe some of the minerals in water are good for you, and there's things around satiety.... But since all water is different it's only if you are really poor might this might matter. You should not be relying on random water for your micro-nutrients.
OK, don't do it for 20 years without more research, but it will not burn you. I don't know what The Action Lab did, but here's National Geographic doing it in a professional lab https://www.youtube.com/watch?v=hMh1lyeNsPc
Osmotic pressure. Same reason why it is a bad idea to swim in Super-Kamiokande. The older experiment IMB eventually failed because the ultra pure water attacked and breached the liner separating it from the ambient salt.
clickbait.. Water has a low pH when you remove all soluble minerals. However, w/o minerals it has no buffer capacity and pH will raise very easily. therefore it is not going to actually burn you.
