The problem of water supply from the public distribution network still poses very serious problems in many cities in developing countries. Intermittent water supply pushes some households to build underground reinforced concrete tanks for water storage to cope with unwanted water breaks. This study that relies on the results of a survey of households in some areas of the city of Brazzaville (Republic of Congo) aims to verify the importance that users attach to the quality of the works constructed. Indeed, the reliability of the tanks resulting in their impermeability to the external environment has a direct impact on the quality of stored water and therefore the use that is made of water daily. Five areas were selected because of their soil moisture. By 256 tanks identified, 143 are made of reinforced concrete and 113 in masonry. The coating materials used to seal the walls are preferably the earthenware tiles (64% of tanks), then the Sika cement (31%). Food painting (5%) is only rarely used. However, 66% of households are not assured of the potability of the water stored. A significant number of households (46%) think that the stored water could be contaminated with noxious substances seeping from the outside through the walls of the tanks. The issue of sealing of underground water tanks, especially in areas where the water table is shallow, seems concerned users.