Steve, I have used condesate from an AC, and I know of no reason not to use it. Aluminium is not soluble in distilled water. However, I get my wife to catch the ice and water as the refrigerator defrosts, and I use that in my car. I wouldn't use tap water, with it's dissolved minerals. Also, its only pennies to buy de-ionised water from the local pharmacist, and that's what I use in our Airstream. Nick.
Nick Crowhurst, Excella 25 1988, Dodge Ram 2500 Cummins Diesel. England in summer, USA in winter.
"The price of freedom is eternal maintenance."