Whilst discounting the likely, frequent widespread use of natural wetlands for liquid-effluent treatment within the UK, a brief history of the global development of constructed wetlands is given. The designs and types of flora and fauna used within UK-based constructed wetlands, are discussed. Then, a case study of the constructed wetlands used at the Wildfowl and Wetlands Trust, Gloucestershire, UK, highlights how constructed wetlands can be used successfully for decontaminating liquid effluent within the UK.