I boil natural spring water (Evian) in a stainless steel kettle and there is a white residue left behind that I can wipe off with a wet paper towel. What is this? I also notice residue floating in water remaining on bottom of kettle. This does not happen with regular tap water.

  • $\begingroup$ Both spring water and tap water will contain dissolved minerals, e.g. calcium carbonate. Potable water just needs to be feed of poisons and reasonably sterile. Typically potable water isn't pure. $\endgroup$ – MaxW Mar 28 '18 at 16:52
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    $\begingroup$ on the bottle there is usually a list of the mineral content. You've just isolated those minerals. $\endgroup$ – Waylander Mar 28 '18 at 18:00

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