About 75% of the entire surface of the planet Earth is covered by water, with only about 3% of freshwater. The Amazon region has the largest freshwater basin in the world and the uncontrolled growth of the population in this region has become a problem concerning water contamination since a large part of the region’s population obtains water from artesian wells. This study aimed to investigate some physical-chemical parameters of groundwater in the municipality of Caapiranga, Amazonas (AM), Brazil. Water samples obtained from 14 tubular wells were evaluated, as well as a sample of surface water from Lake Caapiranga that passes in front of the municipality. The vast majority of water samples showed low pH, and were of the parameters established for drinking water, aquaculture and animal watering. High levels of nitrate are also found in most samples, which indicates contamination of these waters by domestic effluents. In wells 1, 6, 9 11, and 13 the levels of nitrate were very high and can cause serious diseases in people who use this water for consumption. According to the parameters evaluated, the quality of groundwater in 5 of the 14 wells is unfit for human consumption.