Constructed wetlands redefined as functional wetlands

Constructed wetlands (or "helofytenfilters" in Dutch) are man-made wetlands, which exploit the processes that occur in 'natural' wetlands in such a way that the primary objective is to purify water. Constructed wetlands are used all over the world for this purpose. Over the years, the number of types has increased and there has been great improvement in the clarification of the number of functions a constructed wetland could have. Within cities worldwide, many problems exist, such as risk of flooding, contaminated surface water and the heat-island effect. As an alternative for hard-engineering measurers, eco-engineering measures (such as constructed wetlands) could be used. Such measures are relatively cheap and they have the potential to combine multiple urban functions at the same time. Apart from water purification, constructed wetlands could be used in cities for (among others) recreation, nature, water retention, cooling and feeling of well-being for citizens. There are many possibilities for innovation and improved implementation in urban areas: constructed wetlands could be more successfully implemented in and near cities when different interests and functions are combined within one wetland and when the water purification function is expanded.