Salinity has been a serious problem in Bangladesh’s coastal region for several decades. Coastal vulnerability and the water crisis are exacerbated by sea-level rise, changing climate patterns, frequent natural disasters, and man-made changes to natural settings. Bangladesh’s coastal areas, which are home to 20 million people, face a variety of water-related hazards, ranging from chronic salinity, which reduces agricultural yields and impacts drinking water quality, which affects livelihoods and wipes out agricultural production. In addition, concurrent floods and cyclones contribute to the deterioration of freshwater availability. Water hazards and a lack of sufficient quantity and quality of water aggravate poverty in coastal areas. Understanding the complex dynamics between climate change, water security, human well-being, and economic growth is necessary. This study employs both quantitative and qualitative approaches to comprehend the complexities. By analyzing water pH, the electrical conductance of saturated extract, and other factors associated with salinity, this study investigates the salinity level, its impact on portable water sources, and changes in the natural environment of Anwara coast (South-eastern coast) in Chattogram District. Furthermore, the FGD (Focus Group Discussions) technique is used to understand the long-term effects of water security on local livelihood patterns. This mixed-method approach helps to comprehend the complexities of coastal Bangladesh’s climate change, water security, and livelihood changes. Research findings indicate a significant increase in salinity level in the study area which affects water consumption patterns and leads to livelihood diversification of the South-eastern coastal community in Bangladesh.