This page discusses the process behind distilled and de-ionised water.
About de-ionised water
(here) - slightly alarming: "Demi water is quite aggressive for metals, even for stainless steel. So in many cases plastic materials are used to transport the demi water."
Does this mean that lack of minerals is actually a bad thing
edit: another
linky. "Water readily absorbs gases from the air and is a potent solvent (ultrapure water will dissolve glass, quartz, sapphire, all stainless steels, titanium, aluminum, etc.)" Wow
