
Originally Posted by
Galcobar
Pure water is neither an acid nor a base (or is both), but is highly reactive.
As a practical matter you'll never encounter water as pure as what you're talking about.
The distilled water you get at the grocery store is nowhere near pure enough to be "hungry" to dissolve stuff like the "ultra pure water" (UPW which is a stringently defined category of water) found in laboratories and specialized industrial processes.
BTW, here's an interesting quote from wikipedia on steam irons and distilled water:
Most manufacturers now say that distilled water is unnecessary in their irons, and can also cause malfunction, including spitting and leaking during use. Distilled water is capable of being heated beyond the normal boiling point due to absence of dissolved impurities which provide nucleating points at the normal boiling point. It has been suggested that this superheated (distilled) water in an iron will flash boil when disturbed (as with moving an iron), and cause the iron to spit, leak, and possibly scald the user.
https://en.wikipedia.org/wiki/Distilled_water
This makes me think that the industry trend towards recommending tap water instead of distilled water is probably driven by marketing departments rather than engineering. Distilled water is pure enough that it can be superheated which can lead to spontaneous flash boiling which causes spitting and leaking. The marketing guys don't want Amazon reviews saying their irons suck because they spit and leak so they're overriding engineering's preference for distilled water.