Is there a portable water recycling unit that one could install in their studio apartment to recycle grey water ? Or which is the smallest grey water recycling unit ? And can't someone just pass the grey water thru their reverse-osmosis filter and reuse the water?
You can make your own filter, I think.
When I was kid my father and I constructed our own filter, everything you need is some sand, 'dust coal' and a couple of stones and wool. You can use a bottle of soda, or something like that.
Put the wool on the 'mouth' of the bottle, then put in the coal, stones and sand. Put another bottle under the will to extract the clean water.
I'm not a native English speaker, and I don't know some words. If you want, I can make a drawing to make it more clear to understand.
The Hydraloop water recycling system comes closest to what I was thinking of. It won awards at CES 2020 too. I wish it could be a little smaller. I'm sure other similar products will follow soon.