What is the Minimum Water Discharge for Wastewater Treatment at Home?

I am building a model home with self sustained practice on water and waste management.

My house does not have a big consumption of water all the domestic needs, but still, I wanted to set up a wastewater treatment of water from washing clothes & vessels and bathing.

Suggest a pick and place water treatment setup if available.

What is the minimum water discharge required to set up a small treatment?