Graywater system questions

What state/city/rural netherland are you in? That makes all the difference.

You need to first check with your local health officer or state wastewater management department to see if a graywater system is allowed.

Most jurisdictions will require a septic system even without a flush toilet, and consider kitchen sink and laundry effluent to be blackwater because of high organic loads. Some states allow a reduction in the size of the leach field if there is no flush toilet. Some will allow an engineered wetlands with pretreatment, but the pretreatment systems are often expensive and require electrical power for pumps and alarms.

Unfortunately, the simplest and most environmentally responsible systems are rarely allowed because private residential wastewater is the number one source of groundwater pollution in the US.