Oh don't get me started on that shit. Carbonated water is evil incarnate.
I'll always remember going to the Berlin Zoo in early August with my boyfriend, it was a hot sunny day, 30 degrees celsius and we did a lot of walking, and finally went to the rest area to grab snacks and drinks. We bought a bottle of water each, and I bought a bottle of apple juice in addition to that to get some sugary taste and some vitamins too.
I start sipping my juice and my boyfriend opens his bottle. "Psssht!", the bottle said. My boyfriend frowned. "What do you mean, "psssht"?", he asked the bottle. And thus we learned that the tiny "mit kohlensäure" label in small font meant "carbonated" and we needed to specifically get bottles that said "ohne Kohlensäure".
I was really glad I had bought that additional apple juice, lol.
I seriously don't understand how people drink that shit. It's... ugh. The worst.