Unseen Threats in Our Water: Assessing Bacterial Contamination in Institutional Tap Water and Vended Water (Meruwa) in Otuogidi-Ogbia and Ogbia Main Town, Bayelsa State, Nigeria

Rationale: Safe drinking water is essential for human health, yet bacterial contamination remains a pervasive challenge in resource-limited settings. In the Niger Delta region of Nigeria, aging infrastructure, environmental degradation, and inadequate water quality monitoring contribute to persistent waterborne disease burden. However, no prior study has systematically characterized and compared bacterial contamination in both institutional tap water and informal vended water (Meruwa) in this region, leaving critical evidence gaps for policy and intervention. Objectives: This study aimed to: (i) assess the presence, types, and levels of bacterial contamination in tap water from Bayelsa State College of Health Technology and vended water from Ogbia Main Town; (ii) compare contamination levels and bacterial species distribution between the two water sources; (iii) evaluate compliance with World Health Organization (WHO) drinking water standards; and (iv) provide evidence-based recommendations for water safety interventions. Methods: A total of 47 water samples were analyzed, 23 tap water samples from six campus points and 24 vended water samples from vendors in Ogbia Main Town. Total bacterial counts (TBC) and total coliform counts (TCC) were determined using the plate count method on nutrient agar and MacConkey agar, respectively. Bacterial isolates were identified through Gram staining and biochemical characterization (catalase, coagulase, oxidase, citrate, urease, indole, Kligler iron agar, motility). Compliance was assessed against WHO guidelines (0 CFU/100 mL for coliforms; <500 CFU/mL for heterotrophic bacteria). Results: All samples exceeded WHO standards. Tap water TBC ranged from 3.50 × 10⁶ to 5.00 × 10⁶ CFU/mL (mean 4.32 × 10⁶), and TCC ranged from 3.00 × 10⁶ to 3.80 × 10⁶ CFU/mL (mean 3.21 × 10⁶). Vended water TBC ranged from 3.50 × 10⁶ to 5.30 × 10⁶ CFU/mL (mean 4.24 × 10⁶), and TCC ranged from 3.00 × 10⁶ to 4.00 × 10⁶ CFU/mL (mean 3.21 × 10⁶). No significant difference was observed between water sources for TBC (p = 0.642) or TCC (p = 0.981). Bacterial isolates from tap water included Escherichia coli (28.0%), Staphylococcus aureus (28.0%), Pseudomonas aeruginosa (20.0%), Klebsiella pneumoniae (12.0%), and Enterobacter aerogenes (12.0%). Vended water isolates comprised E. coli (33.3%), Salmonella typhi (25.0%), K. pneumoniae (20.8%), and Citrobacter freundii (20.8%). Species distribution differed significantly between sources (χ² = 24.18, p = 0.0005). Compliance with WHO microbial standards was 0% for both water sources. Conclusion: Institutional tap water and vended water in the study area are universally and heavily contaminated with faecal and opportunistic pathogens, including S. typhi. Both water sources pose substantial health risks, and the widespread assumption that vended water is safer is unfounded. Recommendation: Immediate implementation of routine microbial monitoring, mandatory water treatment for both sources, vendor certification, and targeted hygiene interventions is essential to prevent waterborne disease outbreaks and protect public health. Thus, consumption of untreated water from either source carries risks of acute gastroenteritis, typhoid fever, and opportunistic infections, with particular vulnerability among children, the elderly, and immunocompromised individuals, representing a preventable public health crisis that demands urgent multisectoral action.