Recent climate change and unusual weather patterns have led to an increasing trend in the intensity and frequency of localised heavy rainfall, with significant regional variations in rainfall occurrences across Seoul, Korea. Continuous urban development and city center densification have persistently increased the impervious surface area of urban drainage basins, shortening flood arrival times, raising peak runoff volumes and sharply altering the water cycle in urban areas. Regional causes of flooding in urban areas are mainly attributed to flooding in low-lying areas and insufficient drainage capacity of sewage pipes. Flooding from internal water occurs when concentrated inflow of rainfall exceeds the design capacity of drainage facilities, leading to road surface water pooling in low-lying areas. This is compounded by inadequate pipe capacity or flow, improper pipe gradients, insufficient pump capacity and poor drainage due to sediment buildup and deposition. Therefore, rational and economical design and construction of stormwater drainage facilities that can enhance the capacity for stormwater exclusion in urban areas are crucial. As urbanised areas in many countries have become increasingly exposed to flood risks in recent years, the establishment of appropriate stormwater management plans to address the worsening issue of urban stormwater runoff has become essential. One key feature in controlling drainage capacity and rainfall runoff in urban stormwater systems is the efficiency of stormwater inlets. Capture efficiencies of these inlets are determined by various geometric conditions, including road surface runoff flow, road gradient and inlet design. Empirical formulas for estimating capture efficiency under different inlet shapes and installation conditions have been developed. However, current domestic design and installation spacing standards for stormwater inlet entrances are based on outdated guidelines, necessitating the expansion of design standards that can reflect increased design frequencies. Thus, there is a need to calculate capture flow rates for various inlet sizes considering road conditions (lane, longitudinal and cross slopes) and design frequency variations. There is also a needed to improve design standards. In addition, it is essential to analyse design standards of drainage facilities and stormwater sewer maintenance technologies in urban areas both domestically and internationally to draw implications for policy improvements in stormwater inlet installation and to devise structural and maintenance enhancements that can secure drainage functionality. This study first analysed the current state of stormwater inlet installations in Seoul and identified maintenance issues to establish strategies for securing stormwater drainage functionality. Second, domestic and international cases of stormwater inlet installations were reviewed and standards were designed to propose installation and design guidelines for Seoul’s stormwater inlets. Finally, a hydraulic model experiment was conducted to analyse capture efficiency for different stormwater inlet cover types and a stormwater inlet maintenance plan involving citizen participation was proposed. Observing maintenance practices in advanced countries such as the United States, active involvement by civic groups was notably impactful. Developing a systematic program that encourages civic participation would be crucial. Various incentives for voluntary citizen involvement are also needed, such as offering modest rewards for those participating in cleaning activities or providing educational resources and programs to raise awareness of the importance of stormwater inlets and the necessity of maintenance activities, thus encouraging natural public engagement. This study’s findings can be applied to the design and construction of sewer improvement projects and stormwater inflow facility expansion projects, facilitating the installation of stormwater inlets. Its findings might also be incorporated into Seoul's sewer management manuals (by the Water Regeneration Department), related guidelines and sewer design standards (by the Ministry of Environment). They could also be utilised to verify facility standards for stormwater inlet installation and maintenance and for promoting amendments to current standards.