Water resources are fundamental to Bihar’s socio-economic development, sustaining drinking water needs, agriculture, industry, and rural livelihoods. This study examines Bihar’s extensive surface and groundwater resources, relying on the Gangetic Plains’ river systems including the Ganga, Gandak, Kosi, Sone, and others. The research highlights the state’s diverse water infrastructure such as canals, reservoirs, tubewells, tanks, and lift irrigation, emphasizing their critical role in irrigation and water management. The distribution and management of water bodies in both rural and urban areas are analyzed using recent census data. Ensuring water quality remains a major challenge due to chemical contamination by arsenic, fluoride, and iron, which affects millions in rural Bihar. The Public Health Engineering Department’s comprehensive water quality monitoring protocol and surveillance system, combined with field-level initiatives and capacity building efforts, are key responses to this crisis. Further, the paper reviews major initiatives by the Department of Water Resources including the Ganga Jal Apurti Scheme, Tal Development Plan, rubber dam constructions, river inter-linking projects, and flood management programs. These projects aim to restore ecological balance, augment water availability, improve irrigation, and enhance flood resilience. The study underscores the holistic approach taken by Bihar to address water quantity and quality issues through infrastructural development, environmental conservation, and community participation. This integrated water resource management is essential for Bihar’s climate adaptation, sustainable growth, and improved public health.