Comparative Microbiological and Physicochemical Assessment of Sachet and Bottled Drinking Water in Port Harcourt Metropolis, Nigeria

This study assessed and compared the bacteriological and physicochemical quality of sachet and bottled drinking water sold within Port Harcourt Metropolis, Rivers State, Nigeria. Thirty-two water samples were analyzed, comprising sixteen sachet and sixteen bottled water brands, which were randomly purchased from various locations across the metropolis. Only recently produced products were selected based on production dates. Physicochemical parameters were evaluated using standard methods recommended by the American Public Health Association and the World Health Organization. Microbiological quality was determined through total heterotrophic bacterial count (THBC), total coliform count (TCC), and detection of selected bacterial pathogens. Bacterial isolates were further characterized and subjected to antimicrobial susceptibility testing using the Kirby–Bauer disk diffusion method. The results showed that most physicochemical parameters, including temperature, turbidity, total dissolved solids, and total hardness, complied with WHO guideline values. However, magnesium concentration in bottled water samples (2.76 ± 1.23 mg/L) marginally exceeded the recommended limit (0.2 mg/L). Microbiological analysis revealed significantly higher THBC in sachet water (132.00 ± 72.90 CFU/0.1 mL) compared to bottled water (39.50 ± 16.50 CFU/0.1 mL) (p < 0.05). Although sachet water also exhibited higher TCC values, the difference was not statistically significant (p = 0.1077). Coliforms and faecal indicator organisms, including Escherichia coli, were more frequently detected in sachet water samples. Identified bacterial isolates included E. coli, Staphylococcus aureus, Klebsiella spp., and Enterobacter spp. antimicrobial susceptibility testing demonstrated notable resistance to commonly used antibiotics such as amoxicillin, vancomycin, and erythromycin, while higher susceptibility was observed to levofloxacin and meropenem. Overall, the findings indicate that despite acceptable physicochemical quality, microbial contamination—particularly in sachet water—poses potential public health risks and underscores the need for strengthened regulatory oversight, routine surveillance, and improved production hygiene.