Josh Hoffman wrote:A less expensive option would be to put a 3" WYE and then put an RV gate valve on each side. The gate valves are $20. You can search 3" RV gate valve.
They also have 4" options for more $$ and electric operated ones for even more $$$.
Here is the one that is ready to go and electric but $$$$
https://unitedrvparts.com/products/valterra-ez-valve-electric-waste-valve-3-hub-x-hub-x-hub-double-rotating-flange-e85-8?variant=45365270708527&srsltid=AfmBOorEj4Oi4ApaOvTTHr0joxOlSYJZP8FN8U8mx7CJCQVAs7tHXk4RBdo&gQT=1
Christopher Weeks wrote:I think you're looking for something like this, but ideally, electrified: https://www.thenaturalhome.com/septicdirectorvalve/
But my impression is that most people would not call what you want to call greywater, grey. It'll be black because there will always be fecal residue in the drainpipes before the splitter.
And so you're probably stuck having all the slab-level floor-drains combined (and black), but you could retrofit the structure so that first-floor sink drains and drains from the second floor exit through the wall and into your greywater wetland system.