Cultural ecosystem services of multifunctional constructed treatment wetlands and waste stabilization ponds: Time to enter the mainstream?

•We value the cultural ecosystem services of constructed treatment wetlands and ponds.•We identify 166 systems supporting public recreational and educational activities.•Data on annual visits are collected from a survey of wetland operators and managers.•The site and context factors affecting the public use intensity are identified.•Monetary estimates of recreational benefits for 40 sites worldwide are produced. Natural water treatment systems have long been recognized as sources of ancillary benefits in the form of cultural ecosystem services. To date, there is a lack of quantitative understanding of the extent and welfare impact of such benefits. This paper investigates 166 natural treatment systems worldwide and provides the first quantitative assessment of their recreational and educational benefits. The public use is highly influenced by the type of recreational activities, presence of recreational and educational facilities, and accessibility of the systems. Using value transfer techniques, we estimate the mean and median monetary values of recreational benefits in 8397 and 530€/ha/year, respectively. We compare such value flows with operation and management costs and other ecosystem services provided by these systems.