In developing countries, due to poor sanitation conditions and poor quality of drinking water, typical water-borne diseases and more recently diseases caused by drinking water with high concentrations of nitrates and certain metals like aluminum have increased the concern over the health effects of these compounds. Several articles have shown associations between nitrates and methemoglobinemia in children, and aluminum and Alzheimer disease in adults. This study identified water quality with several parameters in non-conformity with Brazilian drinking water standards (Ruling 36/90): more than 50% of all samples from both regions contained fecal coliforms; some 31% of water samples from wells in Duque de Caxias had excessive nitrate concentrations; 100% of all groundwater samples from both regions showed aluminum concentrations not conforming to the norm, with the same result for 100% of samples from the drinking water distribution system in São Gonçalo and 75% of same in Duque de Caxias. This lack of conformity poses several health risks for the local population.