Gray Water Filter

You're going to need a filtration system that will kill off any body borne pathogens.
Good luck.

I boon dock almost all year long in different dispersed areas and always dump the grey water in different areas around the trailer and what I do is tie or tape an old sock around the end of the hose and the sock will catche any solids and being that the sock is biodegradable it can be buried afterwards.

The only think in my Grey tank is hand washing water and soap, and shower water and soap, perfectly safe to dump, just never had the need.

In some states and some locations that would be legal and in others it is illegal to do that. Don't think you will find a filter, but if you are careful about what goes down the drain I think you could do that now in the places it is legal. I also think those places are few and far between.

Dumping any waste water, whether it be black or gray is not legal in many areas.
Check before you dump!

We will dump a dish pan full of dish water and soap outside in the bushes sometimes as much as once a day. However, we are not camping in a high density area and the dish water is spread out. It's the application rate that needs to be monitored. Many of the critters out there would not want you to filter the stuff.