Water quality is a vital component of environmental and human health. Rajasthan faces chronic water scarcity and variable hydrochemical conditions. This study evaluates physicochemical and hydrochemical parameters across Jaipur, Ajmer, Jodhpur, Bikaner, and Udaipur. Both groundwater and surface water were analyzed during the pre-monsoon 2025 season. Standard methods prescribed by APHA (2017) and BIS (2021) were followed. The analysis covered pH, EC, TDS, hardness, and major ions. Hydrochemical indices such as SAR, RSC, and percent sodium were computed. Statistical methods including correlation, ANOVA, and Water Quality Index (WQI) were applied. Results indicate wide variation in salinity, hardness, and nitrate concentrations. EC and TDS show strong positive correlation, confirming mineral dissolution influence. Nitrate and chloride correlate positively, suggesting anthropogenic contamination from agriculture and sewage. Piper and Gibbs plots highlight dominant geochemical processes. Western districts show evaporation-controlled salinity, while eastern and southern zones indicate recharge influence. WQI values classify Udaipur as “good,” while Jaipur, Jodhpur, Ajmer, and Bikaner fall in “poor” categories. The findings reveal significant spatial heterogeneity in water quality linked to geology and land use. High nitrate and chloride levels pose health and agricultural challenges. The study emphasizes integrating hydrochemical analysis with spatial and statistical modelling. Policy measures should target nitrate control, aquifer recharge, and community-based monitoring. The results serve as a reference for sustainable water resource planning in arid and semi-arid regions of Rajasthan.