Heavy metals within limits are essential for aquatic organisms, plants as well as humans to survive and function, which are toxic at higher levels. The presence of heavy metal ions in water is caused by natural and anthropogenic sources that depend on the local geology, hydrology and geochemical properties of aquifier substances and human activities. The objective of this research work is to detect the heavy metal ions distribution, their possible sources in groundwater and monitoring of health consequence on human population of Kishanganj district, Bihar, India. The heavy metal ions like Cr+6, Mn+2, Fe+3, Cu+2, Zn+2, Cd+2 and Pb+2 in groundwater from different sources of five blocks of Kishanganj district, were examined during summer, rainy and winter seasons (2011-2013).The results reveal that out of 150 hand pump/tap water samples Cr+6, Mn+2, Fe+3,Cu+2, Zn+2 , Cd+2 and Pb+2 ions concentrations varied from 0.00-0.07 mg/l, 0.10-0.53 mg/l, 0.11-0.65 mg/l, 0.03-1.55 mg/l, 0.11-2.76 mg/l, 0.00- 0.005 mg/l and 0.00-0.04 mg/l, whereas among 150 open/ring well water samples these ions varied as 0.00-0.05 mg/l, 0.01-0.43 mg/l, 0.11-0.51 mg/l, 0.02-1.38 mg/l, 0.02-1.86 mg/l, 0.00-0.004 mg/l and 0.00-0.02 mg/l respectively during summer, rainy and winter seasons. The results of the present study have shown that all water samples contain copper and zinc ions within permissible limits of WHO (2008) standards, whereas Cr+6, Mn+2, Fe+3, Cd+2 and Pb+2 ions crossed the maximum desirable limits as recommended by WHO (2008) at some locations of study areas.This study also indicates water pollution hazards and poor drinking water treatment plants in the areas. This research study, therefore, will be helpful for the Governmental and the non- Governmental agencies to take correct and appropriate steps by creating awareness among the people and make them free from disease caused by toxic metals.