You have chosen to take your next step by heading to a septic system. While definitely a bit disgusting, these biological water treatment systems are crucial and are used by most rural households.
For households with a septic system, wastewater from all domestic uses (toilets, showers, sinks, washing machines, etc.) goes to the septic system. The septic system sometimes includes an underground settling tank for solids to settle out of the wastewater, and can also include a septic field which is a series of perforatedDefinition: perforatedpierced with one or more holes pipes buried underground.
As part of the septic system, underground soil, pipes and tanks hosts communities of microorganisms, including bacteria, who digest the waste and nutrients in the wastewater, making it safe to re-enter the ecosystem. Water quality during this process can be impacted if certain cleaning products and detergents are used, as these kill the microorganisms.