Groundwater environmental capacity and its evaluation index is the best approach to measure the impact of exploitation of groundwater resources and, pollution. The chemical and isotope tracers are essential tools for better understanding of groundwater origin, for quantifying water-rock interaction, mixing process and recharge rates, as well as for providing timescales of groundwater flow in groundwater systems, on large spatial and temporal scales. Measurements of isotopic composition of groundwater samples characterised by diversified signatures like seasonal variation, evaporation, water rock interaction or stratification with topography etc. In Southern India with dual monsoon influence, minor modification of the isotopic signal is expected during groundwater recharge. The present study covers a spectrum of subject components related to the ground water scenario of Bangalore city as influenced by the sewage network. The isotopic tool a sophisticated technique that can be used to confirm the changes taking place in the hydrological system.