Nutrient losses from agricultural lands are responsible for degrading water quality and accelerating eutrophication at local and regional scale. Subsurface tile drainage is an agricultural water management measure extensively used in some Northwestern European countries to improve poor internal field drainage and crop production. However, drains constitute artificial and direct conduits responsible for shortening the residence time and accelerating nutrient transport through the hydrological system. Thus, they put the aquatic ecosystems at risk since they promote rapid drainage water transport and reduce the possibility for natural nutrient removal. Edge-of-field technologies have been developed and implemented in the last decades to reduce diffuse pollution caused by nitrogen (N) and phosphorus (P) losses. These technologies are primarily used in critical source areas, where measures at farm-scale appear insufficient to meet the removal targets. They are placed at the edge of agricultural fields and connected to the main drainage pipe. Widely recognized technologies include constructed wetlands, woodchips bioreactors, and filter systems. This chapter presents the results obtained in Denmark from three different and currently investigated edge-of-field technologies treating agricultural drainage water.