Focus on
Greywater Wetlands

Constructed Wetlands
Constructed wetlands are manmade wetlands designed to take advantage of the cleansing benefits of naturally occurring wetlands to treat stormwater, greywater and/or blackwater. They replace the process of the entire traditional water treatment plant.

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Traditional Water Treatment Plant Process:
Water passes through 5 stages: septic tank, emergent marsh, pond, wet meadow, and final treatment. The septic tank screens large solid waste and begins settling out fines. Settlement continues in the emergent marsh and organics cling to plant roots; nitrogen changes to its more readily assimilated form, ammonia, to be taken up by the plants; and, some pathogens die due to exposure to sun and air. The pond finishes the processes begun in the emergent marsh and also uses different kinds of bacteria to transform ammonia to nitrate to harmless nitrous oxide & nitrogen gas. Water then moves into the wet meadow. Wet meadow plants filter out suspended solids (mostly algae) and take up nitrogen ammonia to grow. Bacteria reduce nitrates in this phase. Finally, any remaining pathogens can be killed with UV treatment (preferred) or chlorine (less preferred). If the water is going to be recycled into a building, it can be dyed blue. The harmless blue vegetable dye color identifies the water that has traveled through the wetland. Technical information provided by John Roebig.