On 11 Jun 2011, at 20:11, Matthew Green wrote:
Distilled water *is* virtually non-conductive. It's only the salts and impurities in tap water (and/or river water etc.) that make it moderately conductive.
It's not only the salts. There is some natural ionisation that will result in free H+ and OH- ions. You can't really escape that so even mineral free ultra pure water in a perfectly sealed sterile container (of a material that won't release minerals as the water desperately tries to leach them) will still be *slightly* conductive.
Mineral-free ultrapure water has a resistivity of 18.2 megaohm . cm. I'd call that "pretty damn non-conductive", personally.
Of course, eighteen megaohm water is capable of leaching sodium ions out of glass, so...
DC.