Slow Flows: Participatory Landscapes for Estuarine Sewage Treatment reimagines the Tilbury sewage treatment plant as an open, living landscape where community and ecology interweave. The project transforms an adjacent concrete parking lot into treatment wetlands, using broken concrete reclaimed by local hands to shape gentle dykes and planted wetlands. As the concrete is dragged across the ground, it leaves visible marks that guide the emergence of wetlands and planting, inscribing the narrative of slow, collective transformation into the site. By doing so, the design challenges industrialised, exclusionary infrastructure and reconnects Tilbury’s community to the Thames estuary. The site becomes both a functional water cleansing system and a public commons, offering new grounds for recreation, learning, and collective stewardship along the river’s edge. Through slow, shared action, the landscape heals barriers between people, infrastructure, and the living river.