Before the CW can be used, it is best if the plants are well-developed before they encounter the wastewater effluent, so that they have a strong foundation and greater stress tolerance. <ref> Vymazal, J. (Ed.). (2010). Water and Nutrient Management in Natural and Constructed Wetlands. Springer.</ref> Also, the water level should be appropriate for developing plants. Too much water will prevent oxygen from reaching the plant roots. A few centimeters of water should be in the basin at all times. <ref name = "Purdue">Purdue University. (1998). Individual residence wastewater wetland construction in Indiana. Retrieved from https://engineering.purdue.edu/~frankenb/NU-prowd/buildcw.htm</ref> The water level can be raised gradually to the design operating level.