I've been exploring the idea of a system to allow re-use (drinking) of RV greywater, or at least the freedom to dump in storm drains (I think the requirements are looser about this, but it still has to be somewhat purified)
Greywater is wastewater that does not contain feces. The primary contaminants would be food waste, various soaps (probably only biodegradable or non-antibacterial), and used shower water. I would also probably add urine, after sterilization to remove pathogens.
I was thinking of pre-filtration to remove larger fragments and detritus. Probably with the highest grade of this
-Processing rate would have to be 10 liters per day absolute minimum. 2x to 3x that would be best.
-Weight and volume are both at premium