Water is one of the most essential resources for the sustainable development. With the tendency of urbanization and population growth, a more sustainable urban water system becomes important to create harmonized environment between human and nature, thus it is necessary to discuss integrated urban water management in a holistic manner. In this research, starting from a water management model closed city, hybridity is identified as one character of urban water system and its contributions to improve closed city are studied by collaboration work between two disciplines, water management and urban design. A hypothesis of three components of hybridity of urban water systems is raised, which are spatial hybridity, environmental hybridity and governance hybridity. Each component consists of different elements that are involved and influence each other in urban water system. This report presents the results of spatial hybridity and environmental hybridity in a case study area Zevenkamp in Rotterdam city, the Netherlands. Methodology to analyze and evaluate spatial and environmental hybridity is developed in the perspective of urban design and water management respectively, and then be applied to assess current situation in Zevenkamp. Based on the current analysis results, five future visions are set up according to the concept of closed city and then collaborative design between two disciplines is carried out to clarify the urban layout for each vision. Added values of hybridity in each vision is assessed by quantification, as well as their performance as a closed city. Finally, all the results are compared together and discussed. Some main conclusions can be obtained from this research, which are given as follows: • Hybridity concept addresses the importance of inter-disciplinary work, and it is able to provide a thinking way to promote the collaborative processes. Based on the cooperation between two disciplines in this research, it will be helpful to guide future collaboration when more expertise are involved. • Hybridity concept gives a broader perspective on the discussion of grey and green solutions, which is not conflicting to recent debates on the importance of combination of both types of measures. • Hybridity concept can improve the design of closed city which can enhance citizens’ appreciation on urban water systems without compromising the physical performance of closed city. It will motivate locals to engage in urban water management, which can lead to the study of governance hybridity. In addition, it also inspires urban water managers for more comprehensive understandings to a more sustainable urban water management.