There are two types of treated water processed in sewage treatment tanks, blackwater and greywater. Neither are fit for human consumption, but both have the potential for repurposing.
Greywater comes from sinks, showers, washing machines, dishwashers, et cetera. It is water that does not contain waste from flushing toilets. Greywater contains soap, dirt, or debris from washing your body, mopping your floors, or doing the dishes, either by hand or dish washer. Greywater is suitable for watering the flowerbeds or the lawn.
Blackwater is wastewater from flushing toilets and contains harmful substances such as faeces, urine, and toilet paper. Blackwater is toxic to both human and environmental health as it contains harmful pathogens.
Once treated in a sewage treatment tank where matter particles are filtered out, blackwater is suitable for reuse in flushing toilets but cannot and should not be used for any other purpose.