Abstract: The quest of today for more sustainable management of water asks to look for alternative arrangements where decentralized systems are also included. As the studies on the model of Integrated Water Management (IWM) have extensively discussed, a sustainable system of water has to be ‘in tune’ with the local resources. This implies that both local spatial conditions on the one side, and the citizens and/or local communities on the other, should be engaged. It follows that, in the ‘decentralized thinking’, acquiring knowledge about the local ecosystem is a real need. In this regard, there are evidences that an essential source of information is the inhabitant’s thick deposit of knowledge that results from the everyday experience of the space. Moreover, if design methods like the Water Sensitive Design provide tools to integrate the local spatial conditions in the new systems, motivations from individuals and/or local communities to actually take care of these systems have to be further understood. All this should go hand in hand with a true process of democratization, accountability, and citizens’ empowerment.           Participatory practices, combining survey and design processes, trigger community self learning and capacity building, and inform at the same time challenging visions for real alternatives and place based design solutions. On one side, community mapping and landscape readings are today tackling urban designers in raising the level of the socio ecological questions. On the other hand, placing the citizens at the centre of the design process, as a proactive actors, and not exclusively as end users, it means to develop collaborative tools in systemic design, realization and maintenance. Moreover, co-design can rely on the sense of place belonging, and therefore have an impact in terms of social behaviours. This paper looks at the IWM model from the perspective of co-design, an ultimate tool for citizen’s engagement. In order to further understand whether co-design can actually favour the implementation of decentralized systems of water, a few well-known cases of participation in water sensitive design are discussed and confronted considering process-related and water sensitive aspects.While these examples can be found in both contexts of the global North and South, and there is a vast literature on the interwoven of participative practices and IWM and decentralized models, a contextual approach to case studies is here proposed for enlighten the significance of co design, and its contribution in the current design practice.