A combined two-step process of heterotrophic and electrochemical autotrophic denitrification was developed for the treatment of nitrate-contained drinking water. The water was first treated with heterotrophic biological denitrification and was further purified with electrochemical autotrophic denitrification. The two steps were carried out in a heterotrophication-electrochemical autotrophication combined reactor (HEAR). The lower section performed as the heterotrophic biological reactor and the upper section acted as the electrochemical autotrophic reactor. The bioreactor was a packed bed of anthracite particles, and the water flow was directed in an upward continuous mode. The total nitrate and nitrite concentration, and residual methanol in the effluent were monitored to evaluate the performance of the reactor. The reactor was operated for one year with a feed concentration of 40 mg NO3(-)-N/l. There was no nitrite or residual methanol accumulation in the effluent when the feed C:N ratios (m/m) varied from 2.2 to 2.9. However, slightly excessive methanol dosage could increase the denitrifying capacity of the reactor. The maximum denitrification load of the reactor at 24 degrees C was 10.68 g NO3-/m3 h (47 g NO3-) at C:N = 2.5.