This paper discusses certain issues related to groundwater management within the context of the Brazilian national policy for water resources management. In order to investigate the importance of this water supply source, we interviewed groundwater users in the city of São Paulo, where some 57% of the total water supply comes from this source, and surveyed some of the factors affecting the use of this alternative. These include the existence of a good supply of groundwater, an inadequate public water supply system unable to meet user demands, the degradation of fresh water sources and the reduction in costs involved. Preliminary conclusions suggest the inadequacy of the present system of water resources management, which has not yet integrated the use of groundwater reserves into an overall national program for water resources management.