There is much we still do not understand about how aquatic and terrestrial ecosystems perform the service of water purification. Factors such as location, size, type of soil and vegetation, water flow, temporal variation, and the landscape in which the system exists, determine how much and what type of materials can be processed within a wetland or other aquatic system. Questions remain about how systems function both independently and within the landscape, as well as the impact of different human activities and types and quantities of inputs. For example: What are the different activities that a particular ecosystem might perform and how might these different functions complement or compete with each other? How will climate change and global warming affect this service? What is the efficacy of wetlands and riparian zone restoration? There are large gaps in our ability to identify how ecological knowledge can be best applied in conjunction with policy and management. For example, how can the restoration of wetlands and riparian zones be balanced with landuse practice and pesticide management in the watershed/basin so that restored wetlands and riparian zones are not overwhelmed by landuse practices that cause pollution and sedimentation or divert water.
Support for increased scientific research into these and other questions will help us to understand the ecosystems that provide water purification services and develop the best management techniques to allow us to continue to benefit from them.