[organiclivesmatter]

Hi.
I decided that instead of using tap water for making coffee and etc. I'll buy mineral water for health reasons. However after boiling some mineral waters, a white powder is formed in them. It doesn't have a taste or smell, at least not strong enough to notice for me. It makes coffee taste like it had flour inside. What can this be? Is it toxic? What kind of mineral waters I should buy, so this powder won't appear in them after boiling?

[Corribus]

They call it mineral water for a reason. If you boil the water away, what do you suppose is left behind?

Not a great idea to use mineral or even tap water in an electric coffee maker. You'll have to descale the machine frequently, and you may damage it. Use distilled water.

[organiclivesmatter]

It's not obvious that mineral water after boiling will contain something bad. There are all sorts of minerals in food and we boil it and eat it. There is no information on the bottle that it shouldn't be boiled either. Also, not every mineral water acts like that, just some, don't know what differs them yet.  And I never said I use coffee machine..

You also don't know what happened with that water, you are just a typical forum loser that wanted to make someone feel stupid to feel better with yourself, without giving any valuable information.

[AWK]

Mineral water usually does not boil because it loses its flavor. For cooking purposes, you can use non-carbonated mineral water, low in minerals, and containing as little bicarbonate as possible. For some diseases, you should also avoid higher sodium content.
Only a few mineral waters meet the above criteria - in this choice of European waters, only 6 (and 2 still have too much sodium).
https://www.eupedia.com/europe/european_mineral_waters.shtml