Starting with pure and aluminum I imagine you could get small
amounts of aluminum oxide or aluminum hydroxide (depending on
what other factors in the system might influence the pH) from
its reaction with the small number of dissociated water
molecules.  The equibrium constants would be very small
however.  In other words aluminum does not dissove very much
in pure water if you are not continually supplying new water.

On a related note, the rate of corrosion in an aqueous
solution depends partly on the electrical conductivity of the
solution.  The conductivity depends on the number of ions in
the water, typically from dissoved "minerals".  Salt  water is
more corrosive than "fresh water".

Larry A.  (I'm not a chemist but I play one in the classroom.)

'91 GL with distilled water and the orange stuff

---- Original message ----
>Date: Fri, 30 Apr 2004 18:20:21 +1200
>From: Andrew Grebneff <andrew.grebneff@STONEBOW.OTAGO.AC.NZ>
>Subject: Re: for the record water is not corrosive
>To: vanagon@GERRY.VANAGON.COM
>
>>    and for the record water is not corrosive, gary
>
>Pure (multidistilled) water IS corrosive; it will dissolve
(leach)
>chemicals/elements out of nearly everything it touches until it
>attains an "equilibrium" (actually there is no such thing as
>equilibrium... it is an ideal, not a fact).
>
>Tapwater has plenty of impurities.
>
>Distyilled water will not conduct electricity either. It needs to
>contain plenty of metal ions in order to conduct.
>--
>Andrew Grebneff
>Dunedin
>New Zealand
><andrew.grebneff@stonebow.otago.ac.nz>
>Seashell, Macintosh, VW/Toyota van nut