Evaluation of the Physico-Chemical and Bacteriological Quality of Surface Water used for Watering Market Gardening Crops Lutendele Neighborhood in Kinshasa

This study was conducted in the Lutendele neighborhood of Mont-Ngafula Municipality, Kinshasa Province. Its objective was to assess the physicochemical and bacteriological quality of the water used for irrigating market garden crops in order to determine potential contamination risks and their potential impacts on consumer health. To this end, water samples were manually collected from two sampling points coded E1 and E2 in November 2024. In situ measurements of physicochemical parameters, including temperature, pH, electrical conductivity, and dissolved oxygen, were performed using a WTW multi-parameter probe. Bacteriological analyses consisted of the identification and quantification of Escherichia coli as an indicator bacterium of fecal pollution using the membrane culture method. The results obtained revealed the following average values for the overall parameters measured in situ: Temperature (in °C): 27.3 °C (E1) and 25.4 °C (E2). These values recorded during this study are slightly higher than the limit value (25 °C) set by the WHO guidelines. This slight thermal pollution can be explained by domestic wastewater discharge. pH: 4.98 (E1) to 5.42 (E2). All these average pH values recorded demonstrate that the waters studied are all acidic (pH < 7). This could be explained by the contribution of potentially acidic runoff water, which tends to lower the pH of the waters in the study environment. Dissolved oxygen (in mg/L): 4.52 (E1) to 7.36 (E2). These levels are all below the WHO guideline (≥10 mg/L) for surface water. There is therefore an oxygen deficit in the study environment, linked in part to the organic matter pollution present in these waters. Electrical conductivity (in μS cm−1): 15.58 (E1) and 28.5 (E2). In both samples, the electrical conductivity values recorded comply with the WHO standard, which sets the maximum conductivity value at 200 μS/cm for surface water. As for bacteriological analyses, average Escherichia coli concentrations of 23 (E1) and 50 (E2) were recorded in CFU/100 mL. These values, which do not comply with WHO standards for all surface water, whose normative requirement is (0 CFU/100 mL), indicate significant fecal pollution, which may be explained by the contribution of fecal contaminants carried by runoff water and by the insufficient hygiene measures (hygienic facilities) of the surrounding population. In summary, the results of this study indicate that the irrigation water used for market gardening in the Lutendele neighborhood, Mont-Ngafula Municipality, in the city of Kinshasa, is of poor quality with regard to both the physicochemical and microbiological parameters analyzed, and this is therefore intended as a warning to ensure and protect the health of consumers of market garden products.