An attempt to define "Constructed Wetlands"
Constructed wetlands are man-made systems, designed and constructed to treat wastewater using the natural processes typical of natural wetlands. These natural processes are an interaction and combination of wetland plants, soil and microbial life. Knowledge of these natural processes is used to control the operation and efficiency of the constructed wetlands.

Constructed wetlands can be classified according to the water flow regime: surface flow systems and subsurface flow systems.
Constructed wetlands with subsurface flow may be classified according to the direction of flow into horizontal subsurface flow (HSSF) and vertical subsurface flow (VSSF).
Constructed Wetlands