Hello~I would ask your GP, possibly what they are using to "purifying" the water is causing an allergic reaction, some folks have allergies to many things and their systems are very sensitive, this could be your case as well.
Hello and thank you for your question. Sorry for a delay in response. This is a really interesting question and we encourage you to talk to your doctor about it. This article may shed some light on things.
https://www.healthline.com/nutrition/purified-vs-distilled-vs-regular-water
Every location has their own way of purifying water. Perhaps yours does something that does not agree with you. There is actually a disinfecting process with many which could be causing a reaction resulting in your vomiting. This would be my guess, however, I could not say for certain.
So, typically, purified water has gone through a chemical process while mineral water is derived from natural means.