In this case it’s because it’s nonpotable, where it was manufactured hasn’t passed any of the quality control certificates needed by a health body. Basically it could have bacteria, virus, or toxic substances in it.
Demineralised water along with distilled, ultrapure and deionised are all “safe” to drink. They will however leech salts and minerals out of your body, you do replenish these from your diet so it isn’t a great concern unless you are heavily dehydrated ie you are running the death valley ultra marathon. That would exacerbate electrolyte loss and could lead to chronic Electrolyte Imbalance
Hell you can even drink heavy water without much issue, you’d need to replace about 20% of the water in your body with heavy water for it to get potentially lethal.
#
Latest Answers