[squirtlebonflow]

Why distilled water? It presumably doesn't rain distilled water outside.

[mark-r]

But that's exactly what rain is! Water vapor that has condensed and hasn't been in contact with any minerals or contaminants.

[pests]

How does acid rain work then

[zacharycohn]

There are many minerals added to tap water as part of water treatment. Rain water does not have those. So it technically does rain distilled water!