groundwater, heavy metals, pollution, toxicity
The aim of this study was to assess the quality of groundwater from different regions in Rwanda. Around 40 samples from springs, boreholes and wells were analyzed from 2004 to 2009. Apart from the in situ analysis of temperature, pH, conductivity and TDS using multimeter, conductimeter and pH-meter; nutrients (nitrogen, phosphorus compounds), fluorides and chlorides were analyzed by UV-Spectrophotometer while heavy metals (Pb, Cr, Cd, Fe, Mn, Zn and Cu) were analyzed by Atomic Absorption Spectrometer. The results were compared to the World Health Organization (WHO) standard for drinking water. It was found that 69.4% for pH, 74.07% for conductivity, 5.5 % for the total hardness, 23.8% for TDS of the samples were above the WHO limits. The nutrients results showed that 9.09% for nitrates, 43.33% nitrites of samples exceeded the recommended. The heavy metals concentrations (Pb, Cd, Cr, Fe and Mn levels) in some of the samples were found to be above the guidelines of WHO with 8% for Fe, 39% for Cr, 69.7% for Mn, 60% for Pb, 56% for Cd and 3.3% for Cu. These results indicated different levels of pollution in groundwater of Rwanda. A detailed study looking at different plausible pollution sources should be conducted in order to validate the results and advice on environmental protection of this precious source of drinking water.