Vulnerability to Microbiological Pollution of Tap Water and Groundwater Consumed in the Southern Zone of the City of Brazzaville (Republic of the Congo)

Abstract

Water of good microbiological quality distributed through pipelines fully guarantees the health of the populations who drink it. Its availability would prevent the inadequate use of groundwater that is sometimes poorly treated and of questionable quality. This work proposes to conduct an investigation on the microbiological quality of tap and groundwater consumed in the southern zone of the city of Brazzaville in order to assess their hygienic state and the risks incurred by the populations. Thus, twenty-four (24) water samples taken in four districts underwent microbiological analyses. In tap water, the concentrations of total mesophilic aerobic flora (FMAT) vary from 132 to 48000 CFU / mL and 40% of the samples taken are contaminated by Staphylococcus aureus. Total coliforms bacteria (CT) are more abundant than faecal coliforms (CF), faecal streptococus (SF) and E. coli. Their concentration respectively varies of 2 to 236, 0 to 37, 0 to 6 and of 0 to 10 CFU/100 mL with a respective non-compliance rate of 100, 70, 50 and 30% relative to the WHO standard which is set at 0 CFU/100 mL. However, in groundwater, the FMAT content varies of 85 to 75000 CFU/mL and 78.57% of samples analyzed show contamination with Staphylococcus aureus with concentrations ranging between 1 and 135 CFU/100mL. In addition, 100, 85.71, 42.86 and 21.43% of the groundwater samples were contaminated by CT, CF, SF and E. coli respectively. Test results indicate that all tap and groundwater samples show high levels of contamination with faecal bacteria (faecal coliforms, faecal streptococci and Escherichia coli), total coliforms, Staphylococcus aureus and aerobic mesophilic flora total and are unfit for human consumption. The water consumed in the southern zone of the city of Brazzaville constitutes obvious health risks. It seems necessary to make the population aware of the danger incurred and urgent measures, both individual and by the public authorities, must be taken to remedy this situation.