The book was inspired by the scientific work carried out by the research group of Nireas International Water Research Center (Nireas-IWRC) at the University of Cyprus in the field of wastewater treatment and reuse. The work is led by Dr. Despo Fatta-Kassinos, who is an Associate Professor at the Department of Civil and Environmental Engineering and Director of Nireas-IWRC. The group worked together with Antonis Papatheodoulou, one of the Greece's best children's storytellers, and developed an interesting educational adventure through which children can understand the vital role of water in life. There is increasing recognition of the power of children's early thinking and learning, as well as a belief that science may be of particular importance in early childhood, contributing not only to the future scientific understanding of children, but also to building important skills and attitudes for learning, establishing high levels of scientific literacy and strengthening scientific inquiry. Educating the young generation and increasing awareness on various aspects of the water cycle and wastewater reuse was the motivation for the development of 'The Secret Handbook of the Blue Circle.