What is wastewater flowing out of the tank to the drain field generally called?

The term for wastewater flowing out of the tank to the drain field is effluent. Effluent refers specifically to the treated liquid that exits a septic tank into the drain field, where it can be further processed naturally through soil filtration and microbial activity. This process helps to reduce pollutants before the water reaches groundwater or surface water sources.

In contrast, greywater refers to wastewater generated from household activities such as laundry, dishwashing, and bathing, which is typically considered less contaminated than other types of wastewater. Blackwater refers to wastewater containing fecal matter and urine, mainly from toilets, which is more heavily polluted. Influent describes the incoming wastewater or sewage entering a treatment facility or septic system, rather than the treated water that leaves it.