Not quite as simple as all of that.. Distilled water is highly corrosive, so is RO. In San Diego, the water is not that corrosive due to all the minerals in the water (hard water from the Colorado River).
If you notice, a lot of RO systems use PEX piping on their output. This is because PEX is corrosion resistant. I suspect that the river water is not as ‘hard’ as Detroit water, therefore it will corrode metal.
