The paper employed the risk assessment model of water environmental health of US EPA in order to study the potential health risks,situation of water quality in the lower reaches of Yellow River and reservoir,and determine the main pollutants and priority order of governance. It evaluated the health risks of water environment caused by the drinking water of 5 typical water sources and clarify priority control of pollutants. The results indicated that the concentrations of the genomic carcinogens in reservoirs are 2.5×10-4~1.6×10-3 mg/L for cadmium (Cd), 2.4×10-4~3.5×10-3 mg/L for arsenic (As), 0.0020~0.0170 mg/L for six chromium (Cr(Ⅵ)), while concentrations of physical health hazards are generally lower. Water quality in the health hazards caused by genotoxic risk of the individual in descending order for the hexavalent were Cr(Ⅵ)> Cd > As, while physical health hazards caused by toxic substances in the risk of individuals descending order of Pb>NH+4>Hg>CN-1>volatile phenol. The health risks caused by the carcinogens in drinking water are generally greater than the maximum allowance levels recommended by International Agency for Research on Cancer (ICRP, 5×10-5 a-1). The largest health risks are found in Wohushan and Yuqing reservoirs, where health risk levels were almost at 10-4 a-1. Six chromium is the pollutant of priority control in the five reservoirs.