Re:
>I tend to agree with "Others" since clean tap water around here ISN'T.
>By the way, here at the lab we get our "distilled" water from an
>ion exchange process: first a millipore filter, then two ion-exchange
>beds and what comes out is supposed to be better than distilled.
>Wish I knew the chemistry behind what goes on but I'd bet the ion
>beds extract out all the loose ions and leave only pure water.
>So, I'm actually using deionized water (which I guess is EXACTLY what
>you'd like to use). So you chemists out there, just HOW do the mass
>marketers "make" their distilled water?
>
Distilled water is just that; i.e. it has been boiled and the steam collected
and condensed in a still. Deionized water has had ionized salts removed by
filtration, reverse osmosis, electolysis or some combination of these processes.
This is a "truth in advertising" issue so if the bottle says distilled it
should have been distilled, althought some manufacturers may cheat.
The old wive's tale about distilled water being "ion hungry" may stem from the
fact that distilled water WILL dissolve more salts than most tap water, since
the tap water already may contain some dissolved salts. Note that no water
"attacks" metal -- although oxidants like oxygen, sulfur, chlorine and flourine
do -- the water only aids the process by allowing the transfer of electrons.
Water alone is not even very good at dissolving rust, at least not at normal
pH. The rust color that appears in cooling system water is due to suspended
rust particles.
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