Background: Water is a basic necessity used by humans for both domestic and industrial uses. Next to air, water is essential to life. It takes up about 71% of the earth’s surface. The objective of this study is to determine the bacteriological quality of well water in Enugu urban, Nigeria

Methodology: A total of 60 domestic wells were selected from Abakpa, Obiagu and Achara layouts in Engu urban, Nigeria by stratified random sampling method, with 20 wells selected from each area based on location of well sites and construction parameters. Water samples were collected from each well using a sterile 200ml plastic bottle for bacteriological analysis to estimate total bacteria count in colony forming unit (cfu)/ml, total coliform count in most probable number (mpn)/100ml, and faecal coliform count in most probable number (mpn)/100ml. Bacterial isolates were identified using Gram reaction and conventional biochemical tests including catalase and coagulase for Gram positive bacteria, and oxidase, citrate utilization, hydrogen sulfide, indole, urease, methyl red, Voges Proskauer, and sugar fermentation tests for Gram negative bacteria. Antibiotic susceptibility testing (AST) of each isolate was performed by the disk diffusion method against selected antibiotics including penicillin G (10µg), ciprofloxacin (5µg), streptomycin (10µg), amoxicillin-clavulanic acid (20/10µg), and trimethoprim-sulfamethoxazole (25µg), and result interpreted using the European Committee for Antimicrobial Susceptibility Testing (EUCAST) break points. Comparative statistics of the data was performed using analysis of variance (ANOVA) with p< 0.05 considered statistically significant.

Results: The well water in the three layouts were heavily contaminated as shown by comparatively high mean total bacteria counts of 0.8825±0.66 x10 4 cfu/ml, 0.8435±0.6413 x10 4 cfu/ml, and 0.8384±0.5948 x10 4 cfu/ml for Abakpa, Obiagu and Achara layouts respectively (p= 0.9714). The mean total coliform counts were 5.15±5.284, 5.45±4.31 and 5.05±4.763 mpn/100ml (p= 0.8038), and the mean faecal coliform counts were 2.4±3.393, 2.65±2.796 and 2.05±2.35 mpn/100ml (p= 0.9631) for Abakpa, Obiagu and Achara layouts respectively. A total of 50 pathogenic bacterial isolates were identified; Klebsiella pneumoniae 21 (43.8%), Escherichia coli 13 (30.0%), Proteus spp 6 (12.5%), Pseudomonas aeruginosa 6 (12.5%), and Staphylococcus aureus 2 (4.2%). The AST result shows that 75% of K. pneumoniae, E. coli, Proteus spp and S. aureus were resistant to all five antibiotics tested.

Conclusion: These findings showed high faecal contamination of domestic well water sources, which poses a significant infection risk to the community. Proper water treatment measures and personal hygiene practices are recommended, and well sites should be located at a safe distance from septic tanks, pit latrines, flowing gutters and refuse dump sites.