Assessing the role of groundwater recharge from tanks in crystalline bedrock aquifers in Karnataka, India, using hydrochemical tracers

•The role of recharge from tanks in crystalline aquifers in India has been assessed.•A suite of chemical tracers (stable isotopes, water chemistry) was applied.•Site-specific differences were observed between rural and urban catchments.•Distinct isotopic ratios and hydrochemistry of tank water and groundwater observed.•Tracer results indicate tanks are of limited importance to groundwater recharge.