The infiltration of water in the floodplain of the Paraíba do Sul river is a natural mechanism that promotes the conservation of the hydrographic basin water resources by decreasing the loss of water by runoff or evaporation. The two main economic activities developed in the floodplain of the Paraíba do Sul river are irrigated rice crop and sand mining. Both cause great loss of surface water by evaporation due to large plots of rice and abandoned sand mining pits filled with water. This research aimed to investigate water infiltration into the soil covered with different cover types in the floodplain of the Paraíso sand extraction port, Tremembé municipality, Paraíba do Sul river basin. Five infiltration tests were conducted in the area, including: close to the rice plot, abandoned and operational port sand sites. In general, the soil had low permeability and the infiltration velocity was practically insignificant. However, in the area of natural forest and pasture vegetation the permeability was higher than in the rice and sand pits.