Am I misunderstanding? Isn't this stuff made out of real wood?

Easy mistake to make. Yeah there are a ton of great artists posting on here. It's always impressive.

What makes you think the artist is on Reddit?

Don't think it's OP's painting but yes it really is amazing work.

Maybe in North America that is the definition. Here we make a distinction between rainwater and grey water.

Rainwater needs no treatment to be used on the garden.

Grey water does.

That's why we don't refer to rainwater as grey water

I mean, our mains water is from catchments that are basically collecting rainwater. I'm sure they are full of PFAS as well.

Interesting you refer to rain water as gray water in the US.

For me (and I think generally anyone in Australia) that word is reserved for recycled water, eg from shower, sink etc.

Rain water can easily be used as drinking water provided you have clean gutters, roof, etc and a little bit of treatment.

Rain tanks are incredibly common here and, unless you aren't on town water, are generally used for the garden more than anything else.

California's drought is interesting to watch from afar. It's all the same things we were dealing with 15/20 years ago here in our drought years. A good impetus for change if nothing else. And hopefully some innovation comes out of it.