Historical Evolution of Traditional Chinese Courtyard Drainage Systems

China’s traditional courtyard drainage systems have evolved over millennia, embodying distinctive wisdom in sustainable rainwater management. This study aims to clarify the evolutionary logic of these systems, which shifted from relying on surface runoff to adopting more systematic drainage approaches. This addresses a gap in existing research on the systemic evolution of micro-scale units. From a sustainability perspective, the study also explores the relevance of traditional drainage practices to contemporary sponge city development. This research examines traditional courtyard drainage systems through a comprehensive methodology that integrates literature reviews, historical evidence analyses, and comparative historical research. The results reveal an evolutionary trajectory from localized and passive interventions to more holistic and systematic regulation. This process was driven by three interrelated factors: the natural environment, socio-technical conditions, and ritual–cultural systems. Based on this analysis, the study elucidates the logical connections between historical experiences and contemporary practice across three dimensions of sustainability: environmental, technological, and sociocultural. The findings offer both theoretical and practical insights for improving modern urban stormwater management.