We have the worst water in Australia where I live. Most capital cities have a nice river , good catchments etc, but South Australia is the driest state in the driest continent in the world. We have small catchments and our water is sourced in dry years from the river Murray, and we are at the end of the river, so large amounts of water are retained (by other states)
for irrigation, which reduces the flow, some years to zero. Consequently, the river salinity increases to such levels that plants die.
Distilled water is de-ionised, so that should be inert to aluminium. It takes ions to allow electricity to flow in an engine which causes corrosion. High voltage insulators are sprayed with distilled water to keep them clean, so it works.