Overview Heavy rainfall can be difficult to manage in dense areas where roads, sidewalks and buildings cover much of the ground. With fewer open spaces, rainwater has less room to soak into the ground and can quickly flow into drainage systems. At the same time, neighborhoods with limited vegetation are more exposed to heat and have fewer comfortable public spaces. Addressing these challenges can be difficult where space for new infrastructure is limited. The Seoul Metropolitan Government’s Rainwater Village program took an innovative approach by moving away from the conventional practice of sending rainfall rapidly into sewers. It retrofitted alleys, pavements, and unused spaces in neighborhoods, and treated rainwater not simply as something to be removed but as a resource that can be retained or reused—bringing water and vegetation together and creating greener and more usable neighborhood areas. The program combined permeable paving, rain gardens, vegetated facilities, and household rainwater tanks with resident workshops and expert support. Rather than relying on one large structure, the approach placed smaller water-management and green features across homes, alleys, pavements and public spaces. These measures form a type of blue–green infrastructure that combines water management with vegetation and improvements to neighborhood spaces. Challenge As Seoul urbanized, soil and vegetation were replaced by roads, buildings and other sealed surfaces, reducing the amount of rainwater that could naturally infiltrate into the ground, be stored in soil and plants, or return to the air through plants. Older residential neighborhoods and narrow alleys in Seoul are vulnerable to intense rainfall and heat exposure because of extensive paved and sealed areas, limited greenery, and aging drainage systems. Rainwater has difficulty infiltrating these surfaces and can quickly flow into sewers, while paved surfaces and buildings can hold heat. City officials recognized that this pattern can contribute to flooding, nonpoint-source pollution (pollutants that rainwater washes from roads and other surfaces), heat-island effects, and reduced groundwater recharge. Large flood-control infrastructure alone cannot address the small but consequential problems that occur around alleys, pavements, and homes. A neighborhood-level approach was needed to address these problems closer to where they occur. Solution The Seoul Metropolitan Government started its Rainwater Village program in 2016 by setting up eco-friendly districts in existing neighborhoods. Rainwater Village was designed as neighborhood blue–green infrastructure that complements large drainage systems. After site selection, water-cycle experts worked with residents through workshops to identify local needs and inform the design. The approach treated rainwater as a resource to infiltrate, retain, or reuse, with different measures selected and combined according to site conditions. (Table 1) Infiltration measures. Permeable blocks and paving replace sealed surfaces in alleys, sidewalks, and public space so rainwater can infiltrate or soak into the ground. Vegetated measures. Rain gardens and vegetated swales—shallow planted channels that slow and filter rainwater—temporarily retain water and allow it to pass through soil and plants. They also add greenery and can provide landscape and resting spaces. Storage and use. Rainwater tanks in homes and community spaces allow stored water to be used for non-potable uses, such as cleaning and landscape watering. Participation and expertise. Workshops and technical advice help tailor where facilities should be located, how they should be designed, and how they can be maintained. Residents contribute local knowledge about water pooling, walking conditions, and practical maintenance, while districts and experts provide technical support and help clarify responsibilities. Program integration. The program was linked with housing-environment improvement, urban regeneration, greening, and district maintenance projects. This helped combine rainwater measures with wider neighborhood improvements and bring together space, funding and responsibility. Table 1: Spatial Combination of Rainwater Village Retrofit MeasuresA neighborhood-scale blue-green infrastructure toolkit Space Retrofit Measure Function Expected Benefit Alleys and pavement Permeable blocks and paving Infiltration; less surface runoff Less ponding and walking discomfort Unused plots and road edges Rain gardens and vegetated swales Retention; filtering; planting More shade, greenery and amenity Homes and community space Rainwater tanks and guidance Storage; non-potable reuse Cleaning, watering and learning Operation Resident workshops and inspection Maintenance; awareness Sustainable operation and maintenance Source: Seoul Metropolitan Government (2019); expert's synthesis. Results Seoul developed 10 Rainwater Village sites between 2016 and 2018 and selected three additional sites in 2019, bringing the total to 13 as of 2019. The three sites were allocated a combined project budget of KRW 2.25 billion. In 2020, the city continued the program by inviting proposals for three additional Rainwater Village sites, with support of up to KRW 750 million per site. In Seoul Institute scenario modelling for prospective sites, locally adapted low-impact-development measures reduced modelled runoff by 4.8% in Bon-dong (Dongjak-gu) and 13.1% in Dobong 2-dong (Dobong-gu). The difference reflects site conditions, including impervious surface ratios of 63.2% and 98.1%, respectively. These are scenario-based estimates rather than measured results from completed Rainwater Village sites. Field reviews of existing sites also found differences in facility coverage and maintenance conditions. At six sites built in 2016–2017, permeable paving averaged about 2.6% of site area. The findings point to the importance of more precise site selection, combining vegetated, infiltration and storage measures according to local conditions, and systematic post-installation management. Seoul has since completed seven projects in 2025 and selected 10 projects across nine districts in 2026 under the Rainwater Management Facility Expansion Project. The 2026 program has a total budget of KRW 2 billion, including KRW 1 billion in city funding, and targets small areas where impervious surfaces account for 70% or more of the area. The program emphasizes combinations of vegetated, infiltration, and storage measures tailored to site conditions, rather than relying mainly on permeable paving alone. The 2026 projects build on the same blue–green infrastructure approach through a separate program, demonstrating policy continuity and institutional scaling-up. Lessons Learned Match measures to local conditions. Rainwater measures should be planned around the area’s physical conditions, drainage flow, available space, and how people use the neighborhood. Assessing topography, paved and sealed surfaces, soil, existing greenery, and public space can help determine where facilities should be placed and which combination of measures is appropriate. Operation and maintenance are critical to keeping facilities working. Permeable surfaces require checks for sediment and leaf clogging; rain gardens need seasonal planting and drainage care; and tanks require guidance on water quality, safety, winterization, and mosquito prevention. Regular district-led maintenance, dedicated budgets, and clearly assigned responsibilities should complement resident and volunteer monitoring. Seoul strengthened this principle in 2026 by linking new investment to maintenance accountability: districts with poorly maintained city-supported facilities during the preceding five years receive a scoring penalty, while proposals that combine vegetated, infiltration and storage facilities or include road stormwater management receive additional points. Use pilots to learn before scaling up. Cities adapting the approach should start with a small pilot suited to local rainfall, land use, and maintenance capacity. Reviewing runoff, facility condition, and resident experience can help determine what works and what needs to change before expanding to other neighborhoods. Keep the role of the system clear. Rainwater Village is best understood as a distributed approach that complements existing water and sewer systems. Stored rainwater should be limited to non-potable uses, such as cleaning and landscape watering, rather than treated as an independent drinking water supply. Make resident participation part of ongoing maintenance. Workshops should not end once facilities are installed. Periodic engagement can help residents identify recurring ponding, sediment, and leaf-clogging locations, agree on practical inspection and seasonal cleaning responsibilities, and communicate maintenance needs to district managers. It can also support handover, refresher guidance and resident monitoring as local conditions change. Resources R. Ha. 2019. Optimal Development and Management of Rainwater Villages for Restoring the Water Cycle. The Seoul Institute. Seoul Metropolitan Government. Water Circulation Policy and Water-Circulation Facilities. Seoul Metropolitan Government. 2026. Urban Heat-Island Effects Addressed through Expanded Stormwater Management Facilities. News Release. 19 March. Seoul Metropolitan Government. 2019. 2020 Rainwater Village Development Project Call for Proposals. Seoul Metropolitan Government. 2019. Seoul Expands Rainwater Villages to 13 Sites. Ask the Experts Minseo Kim Urban Planning Specialist Overseas Project Development, Seoul Urban Solutions Agency Minseo Kim specializes in sustainable development, smart technology, and architectural design projects. Prior to joining SUSA, she completed a doctorate in urban design and planning, and participated in many architectural and urban projects. Follow Minseo Kim on Seoul Urban Solutions Agency The Seoul Urban Solutions Agency (SUSA) was established by the Seoul Metropolitan Government to share its urban development experiences with other cities seeking to become sustainable and smart urban domains. Through a wide network of partnerships with the public and private sectors within and outside the Republic of Korea, SUSA works to connect and leverage its wide range of knowledge and resources to assist in solving the development challenges of its partner cities. Leave your question or comment in the section below: View the discussion thread.