Constructed wetlands have been used for more than two decades as household treatment plants and municipal treatment facilities for smaller communities. Experience shows that they have a high level of performance, provided they are properly planned, built, and operated. This technical book summarizes a comprehensive evaluation of long-term experiences and results from larger constructed wetlands in German-speaking regions. The content of the book is divided into the areas of plant technology and implementation process, which considers the individual steps from decision-making through planning and construction to operation. The respective fundamentals are explained in detail, experiences are presented, and illustrated with examples. A significant contribution to optimizing the use of constructed wetlands is derived from the evaluated experiences.