Free Water Surface CW's: Introduction
Surface flow constructed wetlands are most closely mimicking natural wetlands. Surface flow wetlands require more land than subsurface flow systems for the same pollution reduction but are easier and often cheaper to design and build. Among other disadvantages, surface flow wetlands pose a greater risk of exposure to pathogenic organisms and other harmful contaminants. Surface flow wetlands can have greater aesthetic value and wildlife habitat availability.

Depending on layout and vegetation different types of FWS CW's are possible:
Systems with free-floating macrophytes;
Systems with submerged macrophytes;
Systems with emergent macrophytes;
Stabilization ponds: anaerobic, facultative and maturation ponds.
Constructed Wetlands