In 1991, the first subsurface flow constructed wetland for treatment of domestic wastewater was built in Norway. Today, this method is rapidly becoming a popular method for wastewater treatment in rural Norway. This is due to excellent performance even during winter and low maintenance. The systems can be constructed regardless of site conditions.
JENSSEN, P.D. ; MAEHLUM, T. ; KROGSTAD, T. ; VRALE, L. (2005): High Performance Constructed Wetlands for Cold Climates. In: Journal of Environmental Science and Health: Volume 40 , 1343-1353.