Once the wastewater meets the applicable regulatory requirements, wastewater treatment plants can discharge the treated water back into the environment as effluent. The effluent mixes with the existing surface water or groundwater. In that form, it may one day be reused for irrigation or industrial processes or sent for treatment and used as drinking water.
In some cases, if the wastewater has undergone tertiary treatment, the plant can recycle the water, sending it on for reuse in water-intensive industrial or agricultural processes.