Microbiology and Biotechnology Research: An Overview Vol. 10

Diseases caused by drinking contaminated water pose a serious risk to public health. In Nigeria, particularly in the Diobu district of Port Harcourt, Rivers State, the majority of residents rely on boreholes, wells, and other water sources for their daily consumption, often without considering the microbial or chemical quality of these sources. This study was conducted to determine the microbiological and physicochemical characteristics of drinking water sources in Diobu, Port Harcourt, Nigeria. Ten borehole sites and ten popular brands of sachet water sold in Nigeria under the name "pure water" were sampled in Diobu, Port Harcourt. Physicochemical and bacteriological investigations were conducted using standard analytical techniques. The physicochemical analysis showed that sachet water had higher pH values than borehole water, with borehole samples exhibiting a mean pH of 4.37 ± 1.21, below the WHO-recommended range of 6.5–8.5. Total Suspended Solids (TSS) were within permissible limits (30 mg/L), with borehole water having the highest mean (6.5 ± 4.31 mg/L) and sachet water the lowest (2.5 ± 1.5 mg/L). Total Dissolved Solids (TDS) ranged from 15.8 ± 13.5 mg/L in sachet water to 55.6 ± 33.4 mg/L in borehole water. Electrical Conductivity was 33.5 ± 28.4 µS/cm in sachet water and 136.6 ± 73.9 µS/cm in borehole water. Total alkalinity ranged from 0.57 ± 0.29 mg/L (sachet) to 3.29 ± 1.39 mg/L (borehole), while water hardness ranged from 1.95 ± 0.84 mg/L to 10.67 ± 3.21 mg/L, respectively. Biological Oxygen Demand (BOD) was <1 ± 0.00 mg/L in sachet water and 2.13 ± 1.38 mg/L in borehole water. Dissolved Oxygen (DO) levels ranged from 1.72 ± 0.70 mg/L (sachet) to 1.95 ± 0.62 mg/L (borehole), and Chemical Oxygen Demand (COD) ranged from 2.38 ± 1.18 mg/L (sachet) to 11.31 ± 9.49 mg/L (borehole). Turbidity varied from <1 ± 0.00 NTU (sachet) to 1.1 ± 0.64 NTU (borehole). Only COD showed a statistically significant difference (P < 0.05). Microbiological analysis revealed high contamination in borehole water, with a mean total bacterial count of 9.0 × 10^4 CFU/mL, compared with 2.0 × 10^4 CFU/mL in sachet water, which also had the lowest coliform levels among the sources tested. Compared with the other sources, sachet water had the lowest overall bacterial and coliform levels. However, because the total coliform counts were above the WHO threshold of zero per 100 ml, the samples did not comply with international standards. Pathogenic bacteria of public health significance, including Salmonella spp., Pseudomonas spp., Staphylococcus spp., and Escherichia coli, were isolated from the water samples. Five fungal isolates (Penicillium spp., Aspergillus niger, Aspergillus flavus, Trichoderma spp., and Mucor spp.) were also detected.

Borehole water exhibited the highest bacterial contamination, while sachet water had the lowest. These findings suggest that all water sources should be properly treated before domestic use because they are currently unsuitable for human consumption.