Wetlands and aquatic plant systems absorb nutrients from wastewater and use them to support the ecosystem, thus creating a natural buffer (EPA, 1988).  Within the wetland aquatic plants pump oxygen to roots and stems, remove nitrogen and phosphorus from wastewater.  Bacteria and fungi also contribute to break down organic matter to carbon and water (EPA, 1988).  If designed properly, and considerations are made as to proper site selection, the constructed wetland is indeed a viable alternative to traditional wastewater treatment.  These designs draw in wildlife and in turn add an aesthetic appeal to the community (EPA, 1988). 

Of course there are constraints that define where constructed wetlands may be located.  Site Selection is dependant upon four major constraints:  topography, hydrology, soil permeability, and temperature.  If the wetland is to be located at a higher elevation the ground needs to be leveled.  This is expensive so a site located at a lower elevation is more desirable. Hydrology of the area affects how organic material is synthesized in wetlands, so it is important to choose accordingly.  Soil permeability needs to be low so to avoid seepage of wastewater contaminants (EPA, 1988).  Lower temperatures can interfere with biological processes that break down materials.  Therefore the wetlands either needs to be located in a warm climate, or winter storage options for sewerage need to be considered.  Constructed wetlands are cropping up all over the United States in various environmental settings.  Of particular interest are the constructed wetlands located in the northeast.