Urbanization can pose water management challenges in cities while overlooking the possibilities of residents’ lived experience and collaborative action learning. We show how the conceptual model of the Lived Experience of Sustainable Urban Groundwater Level identifies several aspects of local knowledge development through an ex-post case study in Rotterdam’s Flower Neighbourhood (The Netherlands), where too low groundwater levels threaten house foundations. Three types of local knowledge development emerged: (i) performing and monitoring well measurements by residents, (ii) environment-specific insights collected by residents and shared with civil servants, and (iii) collaboration on groundwater management experiments, resulting in empirical groundwater data. Overcoming communication barriers, trust issues, and power dynamics are crucial for effectively retrieving and integrating lived experience into collective learning for urban sustainable development.