The concept of water security includes a diverse range of physical, socio-economic, environmental, and infrastructural water related challenges, traditionally measured by the Water Security Index (WSI). This study presents a disaster management inclusive approach for measuring WSI at the household level. The objective of this study is to assess water insecurity for bankline communities considering river erosion in selected unions in Harirampur, Manikganj, along the river Padma. By employing a mixed-method approach encompassing remote sensing, structured questionnaire survey of households, and participatory techniques, various indicators of water security were evaluated. WSI were calculated by using weighted additive function where component weights were assigned by pairwise ranking method through expert opinion. The results showed that the WSI value was 44.25, classifying the area as water insecure. The system is considered water secured when the WSI value is greater than 56. The scores for the components of WSI, basic household needs, food production, environmental flows, risk management, and independence were 46.87, 69.1, 33.33, 39.37, and 34.27, respectively. Approximately 43.24 km² river eroded, and 17.00 km² river accreted in last two decades. Multiple frequencies of homestead shifting occurred among respondents which had a negative impact on water security. Moreover, the study identified risk factors contributing to water insecurity, such as inadequate disaster preparedness and erosion control measures. Based on these insights, a sustainable framework for addressing water insecurity in erosion-prone areas is proposed which provides actionable recommendations for enhancing resilience and sustainability in water management practices.