Industrial activities and building construction in urban areas have reduced green land. It poses a problem for humans, especially the issue of environmental pollution. Industrial waste containing heavy metals can contaminate groundwater. This research aims to know the metal contamination of groundwater samples in the Jakarta area using the electrolysis and atomic absorption spectrophotometer. The test results showed that two samples contained metals that exceeded the threshold value. Metallic concentrations Ca, Mg, Fe, Cu, Cd, Zn for four samples are still below the maximum allowable threshold value. However, the sodium content on groundwater samples from the area Kosambi, West of Jakarta as 392.4 mg/L, and groundwater from Cilincing, North of Jakarta with sodium as 208.4 mg/L has exceeded the threshold value of the sodium at 200 mg/L. Besides, Mn metal content for Kosambi area of 5.22 mg/L and water samples in Cilincing area of 4.89 mg/L has exceeded the value of Mn content limit which is allowed to be 0.5 mg/L. 
 
Keywords— Metal, Contamination, Ground Water, Electrolysis, Atomic Absorption Spectroscopy