Etude de la qualité physicochimique et microbiologique de l‟eau de forage des zones de Kamenge, Ngagara et Gihanga au Burundi

Abstract

The water from the borehole, drawn from aquifers, is naturally supplied by surface water through rainfall, streams, and infiltration. This water resource is susceptible to microbiological and physicochemical contamination due to human activity. The aim of this research is to study the physicochemical and microbiological quality of borehole water from Gihanga, Kamenge, and Ngagara in Bujumbura. Eleven physicochemical parameters (pH, conductivity, temperature, turbidity, TDS, salinity, calcium, manganese, iron, nitrates, nitrites) and six microbiological parameters (total coliforms, fecal coliforms, Escherichia coli, Salmonella, Shigella, Vibrio cholerae) were studied over three months (November 2025, December 2025, and January 2026) in ten boreholes. Multiparameter instruments, thermometers, photometers, spectrophotometer, atomic absorption spectroscopy, incubators, water baths, flasks, Petri dishes, autoclaves, and culture media such as SSA, VRBA, TCBS, and GSP were used. Data processing was performed using Excel and SPSS. Regarding physicochemical parameters, compliance with EAC 2022 and WHO 2017 standards was achieved, with the exception of salinity, conductivity, and nitrites for certain periods. The average salinity of 0.34 ± 0.08, 0.39 ± 0.36, and 0.35 ± 0.0 exceeded the limits in all boreholes. The concentrations of conductivity, turbidity, iron, temperature, pH, calcium, manganese, nitrates, and TDS were within recommended limits. Nitrite measurements were 1.16 ± 0.28 mg/l and 1.13 ± 0.29 mg/L. and 1.46±0.45 mg/l and are outside the standards according to EAC 20202, which sets the limit at > 0.9 mg/l. On the microbiological side, all the analyzed boreholes do not comply with EAC and WHO standards, which require 0 CFU/100 ml for all parameters analyzed. Average values of 5.04±3.47 CFU, 4.42±33.05 CFU; 3.74±3.44 CFU of total and fecal coliforms; 2.25±2.89 CFU, 1.31±1.03 CFU and 3.18±3.42 CFU of Escherichia coli; 2.25±2.89 CFU, 1.31±1.03 CFU and 3.18±3.42 CFU of Salmonella and Shigella; 2.53 ± 2.2 CFU, 2.3 ± 2.35 CFU, and 2.78 ± 3.01 CFU of Vibrio cholerae at Kamenge, Ngagara, and Gihanga areas, respectively. This contamination endangers the environment and poses a major health risk to residents. To prevent groundwater pollution, it is crucial to properly manage and locate boreholes in suitable areas.