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The present study aims to estimate the residence time of groundwater based on bomb-produced (36)Cl. (36)Cl/Cl ratios in the water samples are determined by inductively coupled plasma mass spectrometry and liquid scintillation counting. (36)Cl/Cl ratios in the groundwater were estimated to be 1.0-2.0 × 10(-12). Estimates of residence time were obtained by comparing the measured bomb-derived (36)Cl concentrations in groundwater with the background reference. Dating based on a (36)Cl bomb pulse may be more reliable and sensitive for groundwater recharged before 1975, back as far as the mid-1950s. The above (36)Cl background concentration was deduced by determining the background-corrected Dye-3 ice core data from the frozen Arctic data, according to the estimated total (36)Cl resources. The residence time of 7.81 × 10(4) y is obtained from extrapolated groundwater flow velocity. (36)Cl concentration in groundwater does not reflect the input of bomb pulse (36)Cl, and it belongs to the era before 1950.