Physico-chemical quality of tap water in an urban environment: The case of the Massengo district, arrondissement n°9 Djiri, Brazzaville

The drinking water supply in the Massengo Soprogi district in Brazzaville's Djiri 9 arrondissement is provided by the Djiri river, whose mineralization dictates that of the water in the distribution network. Tap water in this district was analyzed for various parameters in order to understand the acquisition of mineralization. The physico-chemical analysis of these water samples showed that the water has very little mineralization, and is not very hard due to the geological nature of the Djiri riverbed (sandy soil). The pH values in the wet and dry seasons give the water a weakly acidic nature and, taking into account the concentration of bicarbonate ions, a low level of complete alkalinity. The geochemical processes responsible for this mineralization are mainly: water-rock interaction and ion exchange, and silicate dissolution. The geochemical methods used were the Gibbs diagram and the calculation of a few characteristic ionic ratios. Tap water has a strong aggressive and corrosive tendency, as revealed by Langelier's saturation index and Ryznar's stability index.