The Integrated Constructed Wetland (ICW) Initiative was developed in Ireland with an approach that endeavoured to achieve 'water treatment', 'landscape fit' and 'biodiversity enhancement' targets by an innovative wetland design methodology. Full scale integrated constructed wetlands located in the British Isles were investigated for removal of nutrients. The performance was evaluated by monitoring water quality improvements provided by these low-cost and low-energy natural treatment systems. While microbial ecology of the integrated constructed wetlands were investigated using state-of-the-art molecular techniques.